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Background/Objectives:In this study, we aimed to validate the accuracy of single-frequency bioelectrical impedance analysis (SF-BIA) at 50 kHz to assess total body water (TBW) against the reference technique deuterium dilution (D2O) and to explore if the simple clinical parameters extracellular fluid (ECF) composition and body shape explain individual differences between D2O and SF-BIA (DiffBIA-D2O).Subjects/Methods:We assessed TBW with D2O and SF-BIA in 26 women and 26 men without known disease or anomalous body shapes. In addition, we measured body shape with anthropometry and ECF composition (osmolality, albumin, glucose, urea, creatinine, sodium and potassium).Results:On group average, SF-BIA to predict TBW agreed well with D2O (SF-BIA, 39.8±10.1 l; D2O, 40.4±10.2 l; and DiffBIA-D2O −0.7 l). In four individuals ('outliers'; 15% of the study population), DiffBIA-D2O was high (−6.8 to +3.8 l). DiffBIA-D2O was associated with individual variations in body shape rather than ECF composition. Using gender-specific analysis, we found that individual variability of waist circumference in men and arm length in women significantly contributed to DiffBIA-D2O. When removing the four 'outliers', these associations were lost.Conclusions:In the majority of our sample, BIA agreed well with D2O. Adjusting for individual variability in body shape by anthropometrical assessment could possibly improve the accuracy of SF-BIA for individuals who deviate from mean values with respect to body shape. However, further studies with higher subject numbers are needed to confirm our findings. [ABSTRACT FROM AUTHOR]

This study investigated which aspects of the individuals' activity behavior determine the physical activity level (PAL). Habitual physical activity of 20 Dutch adults (age: 26-60 years, body mass index: 24.5±2.7 kg/m2) was measured using a tri-axial accelerometer. Accelerometer output was used to identify the engagement in different types of daily activities with a classification tree algorithm. Activity behavior was described by the daily duration of sleeping, sedentary behavior (lying, sitting, and standing), walking, running, bicycling, and generic standing activities. Simultaneously, the total energy expenditure (TEE) was measured using doubly labeled water. PAL was calculated as TEE divided by sleeping metabolic rate. PAL was significantly associated ( P<0.05) with sedentary time ( R=−0.72), and the duration of walking ( R=0.49), bicycling ( R=0.77), and active standing ( R=0.62). A negative association was observed between sedentary time and the duration of active standing ( R=−0.87; P<0.001). A multiple-linear regression analysis showed that 75% of the variance in PAL could be predicted by the duration of bicycling (Partial R2=59%; P<0.01), walking (Partial R2=9%; P<0.05) and being sedentary (Partial R2=7%; P<0.05). In conclusion, there is objective evidence that sedentary time and activities related to transportation and commuting, such as walking and bicycling, contribute significantly to the average PAL. [ABSTRACT FROM AUTHOR]

Background:Air-displacement plethysmography (ADP) may be a valid and practical technique to assess body composition in a clinical setting.Objective:This study aimed to assess longitudinal changes in body composition using ADP and to compare it with the deuterium dilution technique.Design:The study was a 6-months dietary intervention, consisting of four phases. The first month, subjects were fed in energy balance (phase I). This was followed by 1 month with an energy intake of 33% of energy requirements (phase II), followed by 2 months at 67% of energy requirements (phase III) and 2 months of ad libitum intake (phase IV). Body composition was assessed using ADP (Bod Pod) and deuterium dilution at baseline and at the end of each phase. The baseline analysis included 111 subjects (88 female). Sixty-one subjects (50 female) completed all measurements and were included in the longitudinal analysis.Results:At baseline, the fat mass (FM) as assessed with the Bod Pod was on average 2.3±4.2 kg (mean±2 s.d.) higher than that assessed with deuterium dilution. The difference in FM between techniques increased significantly with increasing FM (R2=0.23; P<0.001). Both techniques showed significant changes in FM over time P<0.001). On average, FM as assessed with the Bod Pod was 2.0 kg higher than with deuterium dilution (P<0.001). During phase II, there was a significant interaction between time and method, meaning that the Bod Pod showed a larger decrease in FM than deuterium dilution.Conclusions:The Bod Pod was able to detect all changes in the body composition, but consistently measured a higher FM than deuterium dilution. [ABSTRACT FROM AUTHOR]

Objective:To describe the design, measurements and fieldwork of the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) physical activity and body composition validation study, and to determine the potential and limitations of the data obtained.Design:Multicentre validation study.Subjects:A total of 98 children from four different European countries (age: 4-10 years).Methods:An 8-day measurement protocol was carried out in all children using a collaborative protocol. Reference methods were the doubly labelled water method for physical activity, and a three- and a four-compartment model for body composition. Investigated field methods were accelerometers, a physical activity questionnaire and various anthropometric measurements.Results:For the validation of physical activity field methods, it was possible to gather data from 83 to 89 children, laying the basis for age- and sex-specific results. The validation of body composition field methods is possible in 64-80 children and allows sex-specific analyses but has only limited statistical power in the youngest age group (<6 years). The amount of activity energy expenditure (AEE) varied between centres, sexes and age groups, with boys and older children having higher estimates of AEE. After normalisation of AEE by body weight, most group-specific differences diminished, except for country-specific differences.Conclusion:The IDEFICS validation study will allow age- and sex-specific investigation of questions pertaining to the validity of several field methods of body composition and physical activity, using established reference methods in four different European countries. From the participant analyses it can be concluded that the compliance for the investigated field methods was higher than that for the reference methods used in this validation study. [ABSTRACT FROM AUTHOR]

Objective:To study whether eating or physical-activity (PA) habits differ between obese and non-obese monozygotic (MZ) co-twins independent of genetic effects.Methods:Rare MZ pairs discordant for obesity (n=14, body mass index difference 5.2±1.8 kg m–2) and weight-concordant control pairs (n=10, 1.0±0.7 kg m–2), identified through a population-based registry of 24–28-year-old twins (n=658 MZ pairs), completed 3-day food and PA diaries and eating behavior questionnaires. Each twin was asked to compare his/her own eating and PA patterns with the co-twin's behavior by structured questionnaires. Accuracy of energy intake was validated by doubly labeled water.Results:Non-obese co-twins consistently reported that their obese twin siblings ate more food overall, consumed less healthy foods and exercised less than the non-obese co-twins do. However, no differences in energy intake (9.6±1.0 MJ per day vs 9.8±1.1 MJ per day, respectively) in the food diaries or in the mean PA level (1.74±0.02 vs 1.79±0.04, respectively) in the PA diaries were found between obese and non-obese co-twins. A considerable underreporting of energy intake (3.2±1.1 MJ per day, P=0.036) and overreporting of PA (1.8±0.8 MJ per day, P=0.049) was observed in the obese, but not in the non-obese co-twins.Conclusions:On the basis of rare MZ twin pairs discordant for obesity, the co-twin assessments confirmed substantial differences in eating and PA behavior between obese and non-obese persons. These may be overlooked in population studies using food and PA diaries because of considerable misreporting by the obese. [ABSTRACT FROM AUTHOR]

The present study examined whether activity energy expenditure related to body mass (AEE/kg) is associated with maximal aerobic fitness (VO2max), energy balance, and body mass index (BMI) during the 2 hardest weeks of the military basic training season (BT). An additional purpose was to study the accuracy of the pre-filled food diary energy intake. Energy expenditure (EE) with doubly labeled water, energy intake (EI), energy balance, and mis-recording was measured from 24 male conscripts with varying VO2max. AEE/kg was calculated as (EE × 0.9−measured basal metabolic rate)/body mass. The reported EI was lower ( P<0.001) than EE (15.48 MJ/day) and mis-recording of the pre-filled diary was −20%. The negative energy balance (−6±26%) was non-significant; however, the variation was high. The subjects with a low VO2max, a high BMI, and a negative energy balance were vulnerable to low AEE/kg. However, in the multivariate regression analysis only BMI remained in the model, explaining 33% of the variation in AEE/kg. During wintertime BT, AEE/kg is affected by energy balance, VO2max, and BMI. From these three factors, overweight limits high-level training the most. Furthermore, an optimal energy balance facilitates physical performance and enables high training loads to be sustained during the BT season. [ABSTRACT FROM AUTHOR]

Objective. Air diplacement plethysmography (ADP) has become increasingly popular to assess body composition in children. The aim of this study was to compare ADP with deuterium dilution and to investigate the effect of using child-specific prediction equations to correct raw body volume from ADP for thoracic gas volume (TGV) and body surface area (BSA). Methods. Thirty-seven healthy Dutch children (17 girls, 20 boys) aged 10–13 years were recruited. Body volume was measured using the Bod Pod®. Both adult and child-specific prediction equations were used to correct raw body volume from the Bod Pod® for TGV and BSA. Total body water (TBW) was assessed using deuterium dilution. Child-specific densities and hydration fractions of fat-free mass were used to convert body volume and TBW to percentage fat mass (%FM). Correlation and agreement between methods was assessed using linear regression analysis and Bland-Altman plots. Results. Despite a high correlation between the Bod Pod® and deuterium dilution (R=0.91, p <0.001), a significant difference was found between %FM obtained using the Bod Pod® and deuterium dilution (p <0.001), regardless of the equation used to correct raw body volume for TGV and BSA. Bland-Altman plots showed a systematic bias towards a smaller difference between techniques at higher %FM. Conclusion. Significant differences in %FM were found between both methods. Given the underlying assumptions to translate body volume or TBW to %FM, it is recommended to use a 3- or 4-compartment model when assessing body composition in children. [ABSTRACT FROM AUTHOR]

Background:The postprandial responses in (an)orexigenic hormones and feelings of hunger are characterized by large inter-individual differences. Food intake regulation was shown earlier to be partly under genetic control.Objective:This study aimed to determine whether the postprandial responses in (an)orexigenic hormones and parameters of food intake regulation are associated with single nucleotide polymorphisms (SNPs) in genes encoding for satiety hormones and their receptors.Design:Peptide YY (PYY), glucagon-like peptide 1 and ghrelin levels, as well as feelings of hunger and satiety, were determined pre- and postprandially in 62 women and 41 men (age 31±14 years; body mass index 25.0±3.1 kg/m2). Dietary restraint, disinhibition and perceived hunger were determined using the three-factor eating questionnaire. SNPs were determined in the GHRL, GHSR, LEP, LEPR, PYY, NPY, NPY2R and CART genes.Results:The postprandial response in plasma ghrelin levels was associated with SNPs in PYY (215G>C, P<0.01) and LEPR (326A>G and 688A>G, P<0.01), and in plasma PYY levels with SNPs in GHRL (−501A>C, P<0.05) and GHSR (477G>A, P<0.05). The postprandial response in feelings of hunger was characterized by an SNP–SNP interaction involving SNPs in LEPR and NPY2R (668A>G and 585T>C, P<0.05). Dietary restraint and disinhibition were associated with an SNP in GHSR (477G>A, P<0.05), and perceived hunger with SNPs in GHSR and NPY (477G>A and 204T>C, P<0.05).Conclusions:Part of the inter-individual variability in postprandial responses in (an)orexigenic hormones can be explained by genetic variation. These postprandial responses represent either long-term physiological adaptations to facilitate homeostasis or reinforce direct genetic effects.International Journal of Obesity (2008) 32, 1790–1798; doi:10.1038/ijo.2008.195; published online 28 October 2008 [ABSTRACT FROM AUTHOR]

Body-weight management requires a multifactorial approach. Recent findings suggest that an elevated protein intake seems to play a key role herein, through (i) increased satiety related to increased diet-induced thermogenesis; (ii) its effect on thermogenesis; (iii) body composition; and (iv) decreased energy-efficiency, all of which are related to protein metabolism. Supported by these mechanisms, relatively larger weight loss and subsequent stronger body-weight maintenance have been observed. Increased insulin sensitivity may appear, but it is unclear whether this is due to weight loss or type of diet. The phenomenon of increased satiety is utilized in reduced energy-intake diets, mainly in the ad libitum condition, whereby sustained satiety is achieved with sustained absolute protein intake in grams, despite lower energy intake. Elevated thermogenesis and glucagon-like peptide-1 (GLP-1) appear to play a role in high-protein induced satiety. Under conditions of weight maintenance, a high-protein diet shows a reduced energy efficiency related to the body composition of the body weight regained, that is, in favor of fat-free mass. Indeed, during body-weight loss, as well as during weight regain, a high-protein diet preserves or increases fat-free mass and reduces fat mass and improves the metabolic profile. In the short-term this may be supported by a positive protein and a negative fat balance, through increased fat oxidation. As protein intake is studied under various states of energy balance, absolute and relative protein intake needs to be discriminated. In absolute grams, a normal protein diet becomes a relatively high-protein diet in negative energy balance and at weight maintenance. Therefore, ‘high protein negative energy balance diets’ aim to keep the grams of proteins ingested at the same level as consumed at energy balance, despite lower energy intakes.International Journal of Obesity (2006) 30, S16–S23. doi:10.1038/sj.ijo.0803487 [ABSTRACT FROM AUTHOR]

Objective: As the peroxisome proliferator-activated receptor gamma (PPARgamma) plays a central role in fat mass regulation, we investigated whether initial subcutaneous PPARgamma activity is related to fat mass generation during overfeeding. Subjects: Fourteen healthy female subjects (age 25 +/- 4 years, BMI 22.1 +/- 2.3 kg/m2). Design and Measurements: Subjects were overfed with a diet supplying 50% more energy than baseline energy requirements for 14 days. Fasting blood samples were analyzed for leptin, insulin and glucose. Fasting subcutaneous abdominal fat biopsies were obtained for analysis of PPARgamma1, PPARgamma2, aP2 and UCP2 mRNAs. Results: Initial PPARgamma1 and 2, aP2 and UCP2 mRNAs were not related to fat gain (P > 0.12). However, PPARgamma1, PPARgamma2 and aP2 mRNA changes were positively related to changes in plasma leptin (P < 0.05) and, except aP2 (P = 0.06), to fat gain (P < 0.05). PPARgamma and aP2 mRNA changes were positively related (P<0.01), indicating that PPARgamma mRNA levels reflected PPARgamma activity. Conclusion: These data suggest that the ability to increase PPARgamma activity might be involved in the susceptibility to gain weight during a positive energy balance. [ABSTRACT FROM AUTHOR]

Objectives: Accelerometry was used to assess the relationship between the physical activity level (PAL) and time spent on activities of various intensities in children. Design: A total of 20 children aged 8.6±3.3 y wore a triaxial accelerometer (Tracmor2) for 2 weeks. PAL was calculated with Tracmor2 output data. The fraction of time spent on activities with a given level of intensity (low, moderate, high) was calculated. The fractions of time spent on activities of different intensities were compared with previously obtained data for young adults and elderly persons. Results: PAL showed an inverse relation with the percentage of time spent on low-intensity activities (r=-0.76; P<0.0001) and a positive relation with the percentage of time spent on high-intensity activities (r=0.93; P<0.0001). The fraction of time spent on low-intensity activities was smaller in children than in young adults (P<0.05) and elderly persons (P<0.0001), while the fraction spent on high-intensity activities (P<0.0001) was larger. Conclusions: The present data are important for a better understanding of physical activity in children, which is necessary for education and prevention about physical (in)activity in childhood. Our observations suggest that to obtain a higher PAL in children, they should be given the opportunities to perform high-intensity activities. [ABSTRACT FROM AUTHOR]

BACKGROUND:: Reference data for physical activity level (PAL) and activity-related energy expenditure (AEE) are needed for a better understanding of the effect of activity on childhood health, growth and development OBJECTIVE:: Data from 17 studies measuring TDEE (TDEE) with doubly labelled water DLW were combined to construct a reference line for PAL and AEE as a function of age. DESIGN:: A total of 17 studies from the literature were analyzed; 17 on girls and 16 on boys. Children were aged 3-16 y and of Caucasian origin. Weighted least-squares regression was used to obtain reference lines for PAL and AEE as a function of age and gender. The relative numbers of children per study were used as a weighting factor. Basal metabolic rate (BMR) or nonfasted (NF) resting metabolic rate and sex were included in the analysis. RESULTS:: Although there was no difference in PAL between boys and girls, a significant difference in AEE was found between the two sexes. PAL: 0.025 x age+1.40. AEE (MJ/day): boys 0.30 x age+0.025; girls 0.21 x age+0.33. If BMR is measured under NF conditions, the obtained value has to be reduced by 0.21 for PAL and 0.75?MJ/day for AEE. No relation was found between AEE/kg and age. CONCLUSIONS:: PAL and AEE were found to increase with age, showing the importance of age-dependent recommendations. Recommendations for AEE need to be differentiated for sex. To compare PAL and AEE between studies, the measurement conditions of BMR have to be taken into account. The increase in PAL and AEE values can be attributed to an increase in weight, because there was no relation between AEE/kg and age.International Journal of Obesity (2003) 27, 605-609. doi:10.1038/sj.ijo.0802246 [ABSTRACT FROM AUTHOR]

Summary A consensus meeting was held in Bangkok, 21–23 May 2002, where experts and young scientists in the field of physical activity, energy expenditure and body-weight regulation discussed the different aspects of physical activity in relation to the emerging problem of obesity worldwide. The following consensus statement was accepted unanimously. ‘The current physical activity guideline for adults of 30 minutes of moderate intensity activity daily, preferably all days of the week, is of importance for limiting health risks for a number of chronic diseases including coronary heart disease and diabetes. However for preventing weight gain or regain this guideline is likely to be insufficient for many individuals in the current environment. There is compelling evidence that prevention of weight regain in formerly obese individuals requires 60–90 minutes of moderate intensity activity or lesser amounts of vigorous intensity activity. Although definitive data are lacking, it seems likely that moderate intensity activity of approximately 45 to 60 minutes per day, or 1.7 PAL (Physical Activity Level) is required to prevent the transition to overweight or obesity. For children, even more activity time is recommended. A good approach for many individuals to obtain the recommended level of physical activity is to reduce sedentary behaviour by incorporating more incidental and leisure-time activity into the daily routine. Political action is imperative to effect physical and social environmental changes to enable and encourage physical activity. Settings in which these environmental changes can be implemented include the urban and transportation infrastructure, schools, and workplaces.’. [ABSTRACT FROM AUTHOR]

Introduction: Hypocretin deficiency causes narcolepsy, a condition characterized by excessive daytime sleepiness, cataplexy, and fragmented nocturnal sleep. Co-morbid overweight is present in two thirds of narcolepsy patients. Moreover one third of them is obese. Why narcolepsy patients gain weight is not known. They do not seem to eat and/or sleep more during 24h than controls. This study was performed to detect a possible decrease in energy expenditure that could be the cause for the overweight in narcolepsy. This is the first study using a respiration chamber to measure Energy Expenditure in narcolepsy. Materials and methods: Nine hypocretin deficient male patients with narcolepsy-cataplexy, and nine sex, age and body mass index (BMI) matched controls were enrolled. Energy Expenditure was measured for 24h in a respiration chamber. Spontaneous physical activity was measured by a radar system based on Doppler principle. Subjects were given a diet to maintain energy balance based on the Harris–Benedict equation. Total Energy Expenditure (TEE), Overnight Metabolic Rate (OMR) and lowest Sleeping Metabolic Rate (SMRmin) were calculated. In addition, measured SMR was compared with SMR calculated with a prediction equation based on body composition. Results: Narcolepsy patients did not differ from controls in BMI (27.4±3.9 vs. 27.5±4.2; P =9.4) or age (38.1±16.0 vs. 36.8±15.2; P =.86) respectively. There were no differences in TEE (10.6±1.2 vs. 10.6±.80MJ/d; P =.99) OMR (5.7±.73 vs. 6.0±.55MJ/d; P =.35), SMRmin (5.4±.76 vs. 5.4±.51MJ/d; P =.99) and spontaneous activity between narcolepsy patients and matched controls (2862±514 vs. 2732±245counts/d; P =.50). For both groups, measured SMR was closely related to SMR predicted from body composition. Conclusion: Energy expenditure in narcolepsy patients is similar to matched controls. It is conceivable that we were not close enough to onset of the disease, when patients usually gain weight, to detect a possible difference before a new metabolic set point establishes. Acknowledgement: This study was supported by a grant from UCB Pharma. [ABSTRACT FROM AUTHOR]

Adults with severe cerebral palsy (CP) are susceptible to malnutrition and metabolic disorders due to limited daily physical activity and challenges related to eating. We hypothesized that the condition of being underweight arises from inadequate energy intake due to difficulties in eating, rather than heightened total energy expenditure or an elevated resting metabolic rate. The present study encompassed 17 adults with severe CP (classified as GMFSC III-V). Energy intake, utilization, and expenditure were gauged via thorough dietary recordings and double-labeled water (DLW) analyses. Resting metabolic rates were assessed through indirect calorimetry, and metabolic health was investigated via blood samples. Oral motor function, eating assessment during meals, and weight fluctuations throughout the experimental period were also evaluated. We found significant correlations between weight, oral impairments ( p < 0.01), and eating difficulties ( p < 0.05). While total energy expenditure and daily consumption were similar between underweight (UW) and overweight (OW) individuals, significant variability in both expenditure and intake was evident within the UW group. Particularly, those with lower BMIs experienced heightened mealtime impairments and complications. Our present findings indicate that eating difficulties are the central concern for UW status in this population.

Purpose: The effects of growth hormone (GH) treatment on linear growth and body composition have been studied extensively. Little is known about the GH effect on energy expenditure (EE). The aim of this study was to investigate the effects of GH treatment on EE in children, and to study whether the changes in EE can predict the height gain after 1 year., Methods: Total EE (TEE), basal metabolic rate (BMR), and physical activity level (PAL) measurements before and after 6 weeks of GH treatment were performed in 18 prepubertal children (5 girls, 13 boys) born small for gestational age (n = 14) or with growth hormone deficiency (n = 4) who were eligible for GH treatment. TEE was measured with the doubly labelled water method, BMR was measured with an open-circuit ventilated hood system, PAL was assessed using an accelerometer for movement registration and calculated (PAL = TEE/BMR), activity related EE (AEE) was calculated [AEE = (0.9 × TEE) - BMR]. Height measurements at start and after 1 year of GH treatment were analysed. This is a 1-year longitudinal intervention study, without a control group for comparison., Results: BMR and TEE increased significantly (resp. 5% and 7%). Physical activity (counts/day), PAL, and AEE did not change. 11 out of 13 patients (85%) with an increased TEE after 6 weeks of GH treatment had a good first-year growth response (∆height SDS > 0.5)., Conclusions: GH treatment showed a positive effect on EE in prepubertal children after 6 weeks. No effect on physical activity was observed. The increase in TEE appeared to be valuable for the prediction of good first-year growth responders to GH treatment.

Physical activity and body composition show a typical pattern over the lifecycle. Fat-free mass and physical performance generally peak in early adulthood. Here, evidence for a relation between physical activity changes over the life span and the development of sarcopenic obesity is presented. Activity-induced energy expenditure increases with body size and physical activity during growth. The physical activity level, calculated by expressing total energy expenditure as a multiple of resting energy expenditure, gradually increases from early age to adulthood to decrease again in old age. Habitual physical activity has a significant effect on growth of fat-free mass during adolescence and thus on peak fat-free mass and physical performance in early adulthood. Older subjects have a lower fat-free mass and lower physical activity levels but there is no association, suggesting physical activity does not protect against loss of lean body mass at higher age. Prevention of sarcopenic obesity starts with a physically active lifestyle to develop a healthy peak fat-free mass and subsequent prevention of excess fat gain. The change from a physically active to a more sedentary routine in later life requires restriction of energy intake to maintain energy balance., (© 2018 World Obesity Federation.)

Purpose: The aim of this paper is to review the evidence of the association between energy balance and obesity., Methods: In December 2015, the International Agency for Research on Cancer (IARC), Lyon, France convened a Working Group of international experts to review the evidence regarding energy balance and obesity, with a focus on Low and Middle Income Countries (LMIC)., Results: The global epidemic of obesity and the double burden, in LMICs, of malnutrition (coexistence of undernutrition and overnutrition) are both related to poor quality diet and unbalanced energy intake. Dietary patterns consistent with a traditional Mediterranean diet and other measures of diet quality can contribute to long-term weight control. Limiting consumption of sugar-sweetened beverages has a particularly important role in weight control. Genetic factors alone cannot explain the global epidemic of obesity. However, genetic, epigenetic factors and the microbiota could influence individual responses to diet and physical activity., Conclusion: Energy intake that exceeds energy expenditure is the main driver of weight gain. The quality of the diet may exert its effect on energy balance through complex hormonal and neurological pathways that influence satiety and possibly through other mechanisms. The food environment, marketing of unhealthy foods and urbanization, and reduction in sedentary behaviors and physical activity play important roles. Most of the evidence comes from High Income Countries and more research is needed in LMICs.

Energy expenditure is determined by body size and body composition and by food intake and physical activity. Body size and body composition are the determinants of resting energy expenditure. Higher weight results in higher energy requirement through a higher resting requirement because of a higher maintenance cost of a larger body. Activity-induced energy expenditure is the most variable component of total energy expenditure. Smaller and leaner subjects generally move more as activity energy expenditure in larger subjects is not higher in proportion to the cost of moving with a higher body weight. Food intake induces changes in energy expenditure as a function of changes in body size and body composition. In addition, energy restriction induces an adaptive reduction of energy expenditure through a lowering of tissue metabolism and a reduction of body movement. An exercise-induced increase in activity expenditure is a function of the training status. In untrained subjects, exercise induces a larger increase in total energy expenditure than can be attributed to the energy cost of a training program. Trained subjects have a higher performance at the same expenditure through a higher exercise economy.

Background: The upper rates of energy expenditure (EE) and the corresponding regulation of energy intake (EI), as described in younger trained subjects, are not well elucidated in older subjects., Objectives: The aim was to investigate EE in older men during prolonged cycling and determine whether it is sufficiently matched by EI to maintain energy balance. In addition, we investigated appetite ratings and concentrations of appetite-regulating hormones., Design: Six men (mean ± SE age: 61 ± 3 y) completed 2706 km of cycling, from Copenhagen to Nordkapp, in 14 d. EE was measured by using doubly labeled water, and food and drink intake was recorded by the accompanying scientific staff. Energy balance was calculated as the discrepancy between EI and EE and from changes in body energy stores as derived from deuterium dilution. Fasting hormones were measured before and after cycling, and appetite ratings were recorded twice daily., Results: EE (±SE) increased from 17 ± 1 MJ/d before to 30 ± 2 MJ/d during the cycling trip (P < 0.001), which is equivalent to 4.0 ± 0.1 times the basal metabolic rate. Although body weight remained stable during the 14 d of cycling, body fat decreased (-2.2 ± 0.7 kg; P = 0.02) and fat-free mass increased (2.5 ± 0.6 kg; P = 0.01). EI was 25 ± 1 MJ/d during cycling, resulting in a negative energy balance calculated by the EE - EI gap (-5.2 ± 1.2 MJ/d). Calculated from changes in body energy stores, energy balance was also negative (-4.8 ± 2.0 MJ/d) during the first week. In the morning and evening, hunger ratings increased (both P = 0.02), whereas ratings of fullness decreased in the evening (P = 0.04). Fasting plasma concentrations of insulin increased by 120% ± 15% (P = 0.02), glucagon-like peptide 1 (GLP-1) by 60% ± 20% (P < 0.01), and Polypeptide YY(3-36) by 80% ± 30% (P < 0.02) after cycling., Conclusions: Older male cyclists sustained near-maximal rates of EE during prolonged cycling but were unable to upregulate EI to maintain energy balance. Despite the presence of increased motivation to eat, a more profound counteracting physiologic stimulus inhibiting increases in EI was present. This trial was registered at clinicaltrials.gov as NCT02353624., (© 2015 American Society for Nutrition.)

Twin studies with objective measurements suggest habitual physical activity (HPA) are modestly to highly heritable, depending on age. We aimed to confirm or refute this finding and identify relevant genetic variants using a candidate gene approach. HPA was measured for 14 days with a validated triaxial accelerometer (Tracmor) in two populations: (1) 28 monozygotic and 24 dizygotic same-sex twin pairs (aged 22 ± 5 years, BMI 21.8 ± 3.4 kg/m(2), 21 male, 31 female pairs); (2) 52 and 65 unrelated men and women (aged 21 ± 2 years, BMI 22.0 ± 2.5 kg/m(2)). Single nucleotide polymorphisms (SNPs) in PPARD, PPARGC1A, NRF1 and MTOR were considered candidates. Association analyses were performed for both groups separately followed by meta-analysis. Structural equation modeling shows significant familiality for HPA, consistent with a role for additive genetic factors (heritability 57 %, 95 % CI 32-74 %, AE model) or common environmental factors (47 %, 95 % CI 23-65 %, CE model). A moderate heritability was observed for the time spent on low- and high-intensity physical activity (P ≤ 0.05), but could not be confirmed for the time spent on moderate-intensity physical activity. For PPARD, each additional effect allele was inversely associated with HPA (P ≤ 0.01; rs2076168 allele C) or tended to be associated with HPA (P ≤ 0.05; rs2267668 allele G). Linkage disequilibrium existed between those two SNPs (alleles A/G and A/C, respectively) and meta-analysis showed that carriers of the AA GC haplotype were less physically active than carriers of the AA AA and AA AC haplotypes combined (P = 0.017). For PPARGC1A, carriers of AA in rs8192678 spent more time on high-intensity physical activity than GG carriers (P = 0.001). No associations were observed with SNPs in NRF1 and MTOR. In conclusion, HPA may be modestly heritable, which is confirmed by an association with variants in PPARD.

Background & Aims: Little is known about the validity of repeated 24-h dietary recalls (24-HDR) as a measure of total energy intake (EI) in young children. This study aimed to evaluate the validity of proxy-reported EI by comparison with total energy expenditure (TEE) measured by the doubly labeled water (DLW) technique., Methods: The agreement between EI and TEE was investigated in 36 (47.2% boys) children aged 4-10 years from Belgium and Spain using subgroup analyses and Bland-Altman plots. Low-energy-reporters (LER), adequate-energy-reporters (AER) and high-energy-reporters (HER) were defined from the ratio of EI over TEE by application of age- and sex-specific cut-off values., Results: There was good agreement between means of EI (1500 kcal/day) and TEE (1523 kcal/day) at group level though in single children, i.e. at the individual level, large differences were observed. Almost perfect agreement between EI and TEE was observed in thin/normal weight children (EI: 1511 kcal/day; TEE: 1513 kcal/day). Even in overweight/obese children the mean difference between EI and TEE was only -86 kcal/day. Among the participants, 28 (78%) were classified as AER, five (14%) as HER and three (8%) as LER., Conclusion: Two proxy-reported 24-HDRs were found to be a valid instrument to assess EI on group level but not on the individual level., (Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Introduction: Reduced testosterone levels are frequently observed in obese men. Increased aromatase activity may be an etiological factor., Objective: In this study, we evaluate the clinical effects of aromatase inhibition in obesity-related hypogonadotropic hypotestosteronemia (OrHH)., Methods: Double-blind, placebo-controlled, 6-month trial in 42 obese men with a BMI >35 kg/m(2), and a serum total testosterone <10 nmol/l. All patients started on one tablet of 2.5 mg/week, with subsequent dose escalation every month until a serum total testosterone of 20 nmol/l was reached., Endpoints: Psychological function, body composition, exercise capacity, and glucose, lipid, and bone metabolism., Results: Thirty-nine patients completed the study according to protocol. Letrozole decreased serum estradiol from 119.1±10.1 to 59.2±6.1 pmol/l (P<0.001), and increased serum LH from 3.3±0.3 to 8.8±0.9 U/l (P<0.0001) and serum total testosterone from 8.6±0.7 to 21.5±1.3 nmol/l (P<0.0001). Significant effects on the predefined endpoints were not observed., Conclusion: Despite a marked rise in serum testosterone, low-dose aromatase inhibition had no somatic or psychological effects in men with OrHH.

One of the aims of Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) validation study is to validate field measures of physical activity (PA) and energy expenditure (EE) in young children. This study compared the validity of uniaxial accelerometry with heart-rate (HR) monitoring vs. triaxial accelerometry against doubly labeled water (DLW) criterion method for assessment of free-living EE in young children. Forty-nine European children (25 female, 24 male) aged 4-10 yr (mean age: 6.9 ± 1.5 yr) were assessed by uniaxial ActiTrainer with HR, uniaxial 3DNX, and triaxial 3DNX accelerometry. Total energy expenditure (TEE) was estimated using DLW over a 1-wk period. The longitudinal axis of both devices and triaxial 3DNX counts per minute (CPM) were significantly (P < 0.05) associated with physical activity level (PAL; r = 0.51 ActiTrainer, r = 0.49 uniaxial-3DNX, and r = 0.42 triaxial Σ3DNX). Eight-six percent of the variance in TEE could be predicted by a model combining body mass (partial r(2) = 71%; P < 0.05), CPM-ActiTrainer (partial r(2) = 11%; P < 0.05), and difference between HR at moderate and sedentary activities (ModHR - SedHR) (partial r(2) = 4%; P < 0.05). The SE of TEE estimate for ActiTrainer and 3DNX models ranged from 0.44 to 0.74 MJ/days or ∼7-11% of the average TEE. The SE of activity-induced energy expenditure (AEE) model estimates ranged from 0.38 to 0.57 MJ/day or 24-26% of the average AEE. It is concluded that the comparative validity of hip-mounted uniaxial and triaxial accelerometers for assessing PA and EE is similar.

The 9th Stock Conference acknowledged the complex background of genetic, cultural, environmental and evolutionary factors of obesity. Gene-environment interactions underlie the flexibility in body-weight and body-fat regulation, illustrated by the hunter-gatherers' feast and famine lifestyle, the variation in physical activity over the lifespan being highest at reproductive age, the variation in energy intake through 'eating in the absence of hunger', while running the risk of exceeding the capacity of triacylglyceride storage, leading to lipotoxicity and metabolic problems. Perinatal metabolic programming for obesity via epigenetic changes in response to a 'Western diet' results in production of lipid-poor milk and metabolically efficient pups, contributing to the perpetuation of obesity throughout generations. Evolutionary insight from comparative physiology and ecology indicates that over generations activity-induced energy expenditure has remained the same compared to wild mammals, that energy balance might be dependant on protein balance, while the function of taste changed from detection of poison or energy to social drinking and social behaviour. At present, the impact of assortative mating on obesity prevalence is unambiguously positive. The complexity that appeared can only be fully appreciated by setting the data into the context of our evolutionary history., (© 2012 The Authors. obesity reviews © 2012 International Association for the Study of Obesity.)

Obesity represents a strong risk factor for developing chronic diseases. Strategies for disease prevention often promote lifestyle changes encouraging participation in physical activity. However, determining what amount of physical activity is necessary for achieving specific health benefits has been hampered by the lack of accurate instruments for monitoring physical activity and the related physiological outcomes. This review aims at presenting recent advances in activity-monitoring technology and their application to support interventions for health promotion. Activity monitors have evolved from step counters and measuring devices of physical activity duration and intensity to more advanced systems providing quantitative and qualitative information on the individuals' activity behavior. Correspondingly, methods to predict activity-related energy expenditure using bodily acceleration and subjects characteristics have advanced from linear regression to innovative algorithms capable of determining physical activity types and the related metabolic costs. These novel techniques can monitor modes of sedentary behavior as well as the engagement in specific activity types that helps to evaluate the effectiveness of lifestyle interventions. In conclusion, advances in activity monitoring have the potential to support the design of response-dependent physical activity recommendations that are needed to generate effective and personalized lifestyle interventions for health promotion.

In the short-term, gelatin showed stronger hunger suppression and less energy intake compared with other proteins. This study investigated if a supra-sustained gelatin-milk protein (GMP) diet improves weight maintenance (WM) compared with a sustained milk protein (SMP) diet and supra-sustained milk protein (SSMP) diet during a 4-months WM period after 8-week weight loss (WL) in sixty-five healthy subjects (28.6+/-3.4kg/m(2); 44+/-10years). Absolute protein intake was kept constant (sustained) throughout per subject. Diets were: protein(P)/fat(F)/carbohydrate(C): 15/40/45% of energy (En%) (SMP) and 30/25/45 En% (SSMP or GMP) for weeks 9-16. Diets on weeks 17-24: P/F/C: 30/35/35 En% (SMP) and 60/5/35 En% (SSMP or GMP). From weeks 8 to 16, and weeks 16 to 24, changes in BMI were similar between the GMP (-0.4+/-0.6 and 0.3+/-0.7kg/m(2) respectively), and the SMP (-0.7+/-0.9 and 0.1+/-0.7kg/m(2) respectively) and SSMP (-0.6+/-0.6 and 0.3+/-0.6kg/m(2) respectively) diets. Sparing of fat free mass (FFM): increases/decreases in FFM%/fat-mass% from weeks 8 to 16 were similar between the GMP and both control diets, and maintained from weeks 16 to 24. In conclusion, all 3 diets resulted in a successful WM period, while a GMP diet does not improve body weight maintenance and related variables after weight loss compared with a SMP and SSMP diet., (Copyright 2010 Elsevier Inc. All rights reserved.)

It is estimated that Asia will be the home of more than 100 million people with type 2 diabetes by the year of 2025. This region combines a high proportion of the world's population with rapidly rising diabetes prevalence rates. The increase in diabetes in Asia differs from that reported in other parts of the world: it has developed in a shorter time, in a younger age group, and in people with lower body-mass index (BMI). Studies reported that for the same BMI, Asians have a higher body fat percentage, a prominent abdominal obesity, a higher intramyocellular lipid and/or a higher liver fat content compared to Caucasians. These characteristics may contribute to a higher predisposition to insulin resistance at a lesser degree of obesity than Caucasians. The differences in body composition are more pronounced depending on the region. For the same BMI, among three major ethnic groups in Asia, Asian Indians have the highest body fat, followed by Malay and Chinese. Lower insulin sensitivity is already observed in Asian Indian adolescents with a higher body fat and abdominal obesity compared to Caucasian adolescents. In general, Asian adolescents share the same feature of body composition such as higher body subcutaneous fat, lower appendicular skeletal muscle and lower gynoid fat compared to Caucasian adolescents. This unfavourable body composition may predispose to the development of insulin resistance at later age. Genetics may play a role and the interaction with environmental factors (changes in lifestyle) could increase the risk of developing the metabolic syndrome., (Copyright 2009 Elsevier Ireland Ltd. All rights reserved.)

Accelerometers are often used to quantify the acceleration of the body in arbitrary units (counts) to measure physical activity (PA) and to estimate energy expenditure. The present study investigated whether the identification of types of PA with one accelerometer could improve the estimation of energy expenditure compared with activity counts. Total energy expenditure (TEE) of 15 subjects was measured with the use of double-labeled water. The physical activity level (PAL) was derived by dividing TEE by sleeping metabolic rate. Simultaneously, PA was measured with one accelerometer. Accelerometer output was processed to calculate activity counts per day (AC(D)) and to determine the daily duration of six types of common activities identified with a classification tree model. A daily metabolic value (MET(D)) was calculated as mean of the MET compendium value of each activity type weighed by the daily duration. TEE was predicted by AC(D) and body weight and by AC(D) and fat-free mass, with a standard error of estimate (SEE) of 1.47 MJ/day, and 1.2 MJ/day, respectively. The replacement in these models of AC(D) with MET(D) increased the explained variation in TEE by 9%, decreasing SEE by 0.14 MJ/day and 0.18 MJ/day, respectively. The correlation between PAL and MET(D) (R(2) = 51%) was higher than that between PAL and AC(D) (R(2) = 46%). We conclude that identification of activity types combined with MET intensity values improves the assessment of energy expenditure compared with activity counts. Future studies could develop models to objectively assess activity type and intensity to further increase accuracy of the energy expenditure estimation.

Background: Activity-related energy expenditure is the most variable component of total energy expenditure and thus an important determinant of energy balance., Objective: To determine whether body composition is related to physical activity in both men and women., Design: A total of 134 healthy participants were recruited (80 women, 54 men; aged 21+/-2 years; body mass index, 22.0+/-2.4). Physical activity was measured for a period of 2 weeks using a triaxial accelerometer for movement registration (Tracmor). Percentage body fat (%BF) was determined by underwater weighing and deuterium dilution according to Siri's three-compartment model., Results: The participant characteristics-body mass, height and gender together explained a substantial part of the variation in %BF (R(2)=0.75, SEE=4.0%). Adding physical activity to the model increased the explained variation in %BF with 4% (R(2)=0.79, SEE=3.7%, P<0.001). Taking seasonality into account by adding the number of daylight hours as an independent variable further increased the explained variation with 1% (R(2)=0.80, SEE=3.7%, P<0.05). In analogy, the association was evaluated for both genders separately. In women, %BF and physical activity were significantly associated (P<0.001). In men, %BF was only associated with physical activity when seasonality was taken into account as well (P<0.05). This probably resulted from men participating more in season bound sports, because an association was found without adjusting for seasonality when only men with a consistent year-round participation in sports were considered., Conclusion: Evidence was found for an association between body composition and physical activity in both genders. A consistent year-round degree of physical activity appears to be a prerequisite to reveal the association. Moreover, Tracmor-assessed physical activity improves the estimate of %BF when a participant's characteristics are taken into account.

Objective: Obesity results from protracted energy imbalance. Whether this comprises excessive energy intake, lowered physical activity or both, remains disputed., Design: Physical activity energy expenditure, evaluated in three different ways from daily energy expenditure (DEE) measured using doubly labelled water, was examined for trends over time. Data included subjects in Europe (Maastricht, the Netherlands) and North America extending back to the 1980s. These data were compared with measures from the third world, and measures made on wild terrestrial mammals., Results: Physical activity expenditure in Europe (residual of the regression of DEE on basal energy expenditure (BEE)) has slightly but significantly increased since the 1980s. There was no trend over time in physical activity level (PAL=DEE/BEE), or in the residual variance in DEE once mass, sex and age were accounted for. This latter index of physical activity expenditure also significantly increased over time in North America. DEE of individuals in Europe and North America was not significantly different from individuals measured in the third world. In wild terrestrial mammals, DEE mostly depended on body mass and ambient temperature. Predicted DEE for a 78 kg mammal living at 20 degrees C was 9.2 MJ per day (95% CI: 7.9-12.9 MJ per day), not significantly different from the measured DEE of modern humans (around 10.2-12.6 MJ per day)., Conclusion: As physical activity expenditure has not declined over the same period that obesity rates have increased dramatically, and daily energy expenditure of modern man is in line with energy expenditure in wild mammals, it is unlikely that decreased expenditure has fuelled the obesity epidemic.

The study aimed to compare differences in physical activity, the relationship between physical activity and body composition, and seasonal variation in physical activity in outpatients with anorexia nervosa (AN) and healthy controls. Physical activity (CM-AMT) and time spent in different intensities of 10 female individuals with AN and 15 female controls was assessed across three seasons along with the percentage body fat. The two groups did not differ in their physical activity and both demonstrated seasonal variation. The percentage body fat of individuals with AN, but not that of the controls, was negatively related to CM-AMT and time spent in low-moderate intensity activity (LMI). Seasonal variation in physical activity emerged with increases in engagement in LMI during the summer period for both groups. Possible interpretations of the finding that decreased physical activity was related to a normalization of percentage body fat in the individuals with AN are discussed and implications for treatment are highlighted.

The objectives of this study were to compare daily physical activities, and activities performed according to a structured protocol, measured with tri-axial accelerometers (Tracmor-4), between lean and overweight children. Fourteen overweight children (59.8+/-9.5 kg) and fifteen lean matched controls (47.2+/-8.7 kg) wore the Tracmor-4 daily, during 12+/-1.3 h, for one week in their home environment. Of these, 24 children participated in a sports afternoon, where they performed activities according to the same structured protocol. In addition, physical activity was estimated using a modified Baecke questionnaire. Body composition was determined. Total mean Tracmor counts/day were significantly lower for the overweight children than for the lean (overweight: 46.1+/-6.9 vs. lean: 54.4+/-11.2 kCounts/day, p=0.02), while reported activities (Baecke score) were similar. When performing activities according to the structured protocol, there was no difference in mean Tracmor counts between the two groups (overweight: 36.3+/-6.9 vs. lean: 34.7+/-6.6 kCounts, p=0.6). Daily physical activities were inversely related to percentage body fat (r(2)=0.29, p<0.01); structured activities were not. As compared to lean children, overweight children moved less without being aware of it; yet exerted the same movements per activity. We conclude that in overweight children daily physical activities were reduced and structured activities performed according to instructions were not. In order to prevent progressive overweight or obesity, overweight children should take part in as many as possible structured and scheduled sports activities throughout the week, and be encouraged to behave physically active in daily life.

Objectives: Several animal studies have shown that bladder performance improves as a result of diuresis. Whether increased urine output also has beneficial effects on elderly male bladder function and lower urinary tract symptoms is unknown., Methods: We performed a randomized placebo-controlled trial of 141 men, 55 to 75 years of age, with moderate lower urinary tract symptoms. The experimental group drank 1.5 L of extra water daily. The control group consumed one tablespoon of placebo syrup daily. After 6 months, we evaluated bladder contractility, voided volumes, and the severity of lower urinary tract symptoms. The actual increase in water consumption was measured using the deuterium urine dilution method., Results: Water consumption in the intervention group increased by 359 mL (95% confidence interval [CI] 171 to 548) per 24 hours compared with the control group. At 6 months, no statistically significant effect was found in the maximal flow rate (0.9 mL/s, 95% CI -0.4 to 2.2) compared with placebo. A statistically significant effect was found for bladder pressure (20 cm H2O, 95% CI 6 to 34) and bladder wall stress (1.9 N/cm2, 95% CI 0.3 to 3.5). In addition, it showed that the experimental group had greater maximal (44 mL, 95% CI -1 to 90) and average (26 mL, 95% CI 1 to 51) voided volumes per urination. The subjective effect parameters improved in both groups, but no statistically significant differences were found between the two groups., Conclusions: It seems possible to improve some aspects of male bladder function by drinking more water. However, the effects are too small to be clinically relevant.

Background: Vitamin A deficiency makes children vulnerable to infections and influences the outcome of various infections. In 1993 vitamin A deficiency was found to be a public health problem in Bungoma district of western Kenya., Objective: To determine the prevalence of vitamin A deficiency, anaemia and malaria parasitaemia and to correlate these with haemoglobin, ferritin and acute phase response., Design: A cross-sectional study., Setting: Bungoma district of western Kenya., Subjects: Three hundred and three children aged one to three years were studied., Main Outcome Measures: Serum retinol, haemoglobin, serum ferritin, alpha-1 acid glycoprotein, C-reactive protein and malaria parasite density., Results: Twentynine percent of the children had severe vitamin A deficiency, 92% had anaemia (haemoglobin less than 10 g/dl) 24(7%) of these were severely anaemic while 76% had malaria parasitaemia. There was no significant difference in the retinol levels of children with malaria parasitaemia and those without malaria parasitaemia (P = 0.6). Retinol levels were significantly lower among children with high C-reactive protein (P < 0.001). Malaria parasitaemia negatively correlated with haemoglobin (r = -0.13, P < 0.05) and C-reactive protein (r = 0.21, P < 0.01). There was no difference in haemoglobin level of children with normal serum retinol and those with low serum retinol (P = 0.16). Ferritin did not differ significantly among children with normal haemoglobin and those with low haemoglobin (P = 0.13)., Conclusion: Vitamin A deficiency and anaemia are a public health problem among the children studied. The high prevalence of vitamin A deficiency may have resulted from acute phase response induced by infections.

Objectives: The aim of the study was to validate a diet history interview (DHI) method and a 3-day activity registration (AR) with biological markers., Subjects and Study Design: The reported dietary intake of 33 rheumatoid arthritis patients (17 patients on a Mediterranean-type diet and 16 patients on a control diet) participating in a dietary intervention study was assessed using the DHI method. The total energy expenditure (TEE), estimated by a 3-day AR, was used to validate the energy intake (EI). For nine subjects the activity registration was also validated by means of the doubly labelled water (DLW) method. The excretion of nitrogen, sodium and potassium in 24-h urine samples was used to validate the intake of protein, sodium and potassium., Results: There was no significant difference between the EI and the TEE estimated by the activity registration or between the intake of protein, sodium and potassium and their respective biological markers. However, in general, the AR underestimated the TEE compared to the DLW method. No significant differences were found between the subjects in the Mediterranean diet group and the control diet group regarding the relationship between the reported intakes and the biological markers., Conclusion: The DHI could capture the dietary intake fairly well, and the dietary assessment was not biased by the dietary intervention. The AR showed a bias towards underestimation when compared to the DLW method. This illustrates the importance of valid biological markers.

The aim of this study was to use a novel method to examine and compare physical activity levels in four different groups of men to investigate the impact of modernity on activity levels. Physical activity levels of four different groups of men were measured and compared, using a tri-axial accelerometer (Tracmor). The first group (HA = historically active) were actors in a historical theme park who play the part of Australian settlers 150 years ago, the second were sedentary modern-day office workers (MS = modern sedentary), the third men who had successfully lost weight (SWL) in a modern men's weight loss program and the last, men who were unsuccessful (UWL) in the same program. Men who had successfully lost weight in a weight loss program were active at a level similar to that of men performing activity at a level carried out historically. Both of these groups were in turn significantly more active than modern-day sedentary workers (p < 0.05) and men who had not been successful at losing weight (p < 0.01). A linear regression between weekly average activity levels and the degree of waist size loss showed a significant positive association (r = 0.52, p < 0.01). The data suggest that a higher activity level facilitates the maintenance of long-term weight loss and this level is likely to approximate activity levels in the past. For the prevention and treatment of obesity an increase in physical activity is necessary, because (long-term) weight loss or weight maintenance is unlikely to occur when people are as sedentary as most people are today.

Objectives: Accelerometry was used to assess the relationship between the physical activity level (PAL) and time spent on activities of various intensities in children., Design: A total of 20 children aged 8.6+/-3.3 y wore a triaxial accelerometer (Tracmor2) for 2 weeks. PAL was calculated with Tracmor2 output data. The fraction of time spent on activities with a given level of intensity (low, moderate, high) was calculated. The fractions of time spent on activities of different intensities were compared with previously obtained data for young adults and elderly persons., Results: PAL showed an inverse relation with the percentage of time spent on low-intensity activities (r = -0.76; P < 0.0001) and a positive relation with the percentage of time spent on high-intensity activities (r = 0.93; P < 0.0001). The fraction of time spent on low-intensity activities was smaller in children than in young adults (P < 0.05) and elderly persons (P < 0.0001), while the fraction spent on high-intensity activities (P < 0.0001) was larger., Conclusions: The present data are important for a better understanding of physical activity in children, which is necessary for education and prevention about physical (in)activity in childhood. Our observations suggest that to obtain a higher PAL in children, they should be given the opportunities to perform high-intensity activities.

Aim: Parents of children treated with growth hormone (GH) frequently report to the paediatrician that their children have become more physically active. In the present study, activity patterns of GH-treated children were measured and compared to those of healthy controls., Methods: Subjects were 25 children at the start of GH treatment (age 8.4 +/- 2.6 y) and 19 age- and gender-matched controls (age 8.8 +/- 3.2 y). Physical activity was assessed with a tri-axial accelerometer for movement registration over two separate 2-wk intervals, one before the start of GH treatment and one 2 wk after the start of treatment. GH-treated subjects were categorized as poor responders (change in height over 1 y <0.7 SDS, n = 15) or good responders (change in height over 1 y >0.7 SDS, n = 10)., Results: Before therapy, good responders showed a significantly lower physical activity compared to healthy controls, spending significantly less time on high-intensity activities. This difference disappeared 2 wk after the start of therapy. Physical activity in poor responders was not significantly different from controls before and after 2 wk of GH therapy., Conclusion: Children who respond well to GH therapy (change in height >0.7 SDS) showed a reduced amount of physical activity before therapy, which was normalized after 2 wk of GH therapy.

The metabolic and temperature response to mild cold were investigated in summer and winter in a moderate oceanic climate. Subjects were 10 women and 10 men, aged 19-36 years and BMI 17-32 kg/m2. Metabolic rate (MR) and body temperatures were measured continuously in a climate chamber with an ambient temperature of 22 degrees C for 1 h and subsequently 3 h of 15 degrees C. The average metabolic response during cold exposure, measured as the increase in kJ/min over time, was significantly higher in winter (11.5%) compared to summer (7.0%, P < .05). The temperature response was comparable in both seasons. The metabolic response in winter was significantly related to the response in summer (r2 = .47, P < .001). Total heat production during cold exposure was inversely related to the temperature response in both seasons (summer, r2 = .39, P < .01; winter r2 = .32, P < .05). In conclusion, the observed higher metabolic response in winter compared to summer indicates cold adaptation. The magnitude of the cold response varies, but the relative contribution of metabolic and temperature response was subject specific and consistent throughout the seasons, which can have implications for energy balance and body composition.

Background: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure., Objective: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age., Design: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE)., Results: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01)., Conclusions: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.

Objective: Walking is an important mode of exercise and is likely to represent a major component of nonexercise activity thermogenesis. The question arises, how best to quantify walking-energy expenditure (EE) in free-living individuals. The triaxial accelerometer for movement registration (Tracmor) is a valid measure of body displacement and so we wanted to evaluate this tool for quantifying walking-EE., Hypothesis: In this study, we test the hypothesis that walking-EE, measured in a Room Calorimeter, can be predicted from Tracmor output using a regression equation derived from a brief Tracmor/treadmill/Metabolic Cart protocol., Design: First, 11 healthy subjects completed a 40-min procedure whereby they wore a Tracmor unit and walked on a treadmill at 0, 1, 2 and 3 mph while EE was measured using a Metabolic Cart. This allowed a regression equation to be defined for each subject to convert Tracmor output to EE. Each subject then entered a Room Calorimeter wearing the Tracmor Unit and walked at two self-selected velocities ('slow', 'fast') while EE was measured. 'Tracmor/regression equation' predictions of walking-EE were compared with Room Calorimeter measurements of walking-EE for the two velocities., Results: The 'Tracmor/regression equation' prediction of EE for walking slowly was 6.36+/-1.67 kJ/min, and for walking fast it was 11.0+/-2.60 kJ/min. Room Calorimeter measurements were 6.43+/-1.85 and 10.9+/-3.03 kJ/min, respectively. The intraclass correlation coefficient for slow-paced walking was 0.93 (P<0.001), and for fast-paced walking it was 0.82 (P<0.005)., Conclusions: When combined with laboratory measures of EE, the Tracmor accelerometer provides useful data on walking-EE and is applicable to free-living individuals.