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Background: There remains no consensus about the optimal dietary composition for sustained weight loss. Objective: The objective was to examine the effects of 2 dietary macronutrient patterns with different glycemic loads on adherence to a prescribed regimen of calorie restriction (CR), weight and fat loss, and related variables. Design: A randomized controlled trial (RCT) of diets with a high glycemic load (HG) or a low glycemic load (LG) at 30% CR was conducted in 34 healthy overweight adults with a mean ([+ or -] SD) age of 35 [+ or -] 6 y and body mass index (kg/[m.sup.2]) of 27.6 [+ or -] 1.4. All food was provided for 6 mo in diets controlled for confounding variables, and subjects self-administered the plans for 6 additional months. Primary and secondary outcomes included energy intake measured by doubly labeled water, body weight and fatness, hunger, satiety, and resting metabolic rate. Results: All groups consumed significantly less energy during CR than at baseline (P < 0.01), but changes in energy intake, body weight, body tat, and resting metabolic rate did not differ significantly between groups. Both groups are more energy than provided (eg, 21% and 28% CR at 3 mo and 16% and 17% CR at 6 mo with HG and LG, respectively). Percentage weight change at 12 mo was -8.04 [+ or -] 4.1% in the HG group and -7.81 [+ or -] 5.0% in the LG group. There was no effect of dietary composition on changes in hunger, satiety, or satisfaction with the amount and type of provided food during CR. Conclusions: These findings provide more detailed evidence to suggest that diets differing substantially in glycemic load induce comparable long-term weight loss. KEY WORDS Glycemic load, caloric restriction, body weight, metabolism

Background: Little is known about the determinants of individual variability in body weight and fat loss after gastric bypass surgery or about the effects of massive weight loss induced by this surgery on energy requirements. Objectives: The objectives were to determine changes in energy expenditure and body composition with weight loss induced by gastric bypass surgery and to identify presurgery predictors of weight loss. Design: Thirty extremely obese women and men with a mean ([+ or -] SD) age of 39.0 [+ or -] 9.6 y and a body mass index (BMI; in kg/[m.sup.2]) of 50.1 [+ or -] 9.3 were tested longitudinally under weight-stable conditions before surgery and after weight loss and stabilization (14 [+ or -] 2 mo). Total energy expenditure (TEE), resting energy expenditure (REE), body composition, and fasting leptin were measured. Results: Subjects lost 53.2 [+ or -] 22.2 kg body weight and had significant decreases in REE (-2.4 [+ or -] 1.0 MJ/d; P < 0.001) and TEE (-3.6 [+ or -] 2.5 MJ/d; P < 0.001). Changes in REE were predicted by changes in fat-free mass and fat mass. The average physical activity level (TEE/REE) was 1.61 at both baseline and follow-up (P = 0.98). Weight loss was predicted by baseline fat mass and BMI but not by any energy expenditure variable or leptin. Measured REE at follow-up was not significantly different from predicted REE. Conclusions: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain. 2003;78:22-30. KEY WORDS Obesity, weight loss, energy expenditure, fat mass, fat-free mass, body water, gastric bypass surgery, energy requirements

Background: The relative influence of diet and physical activity on body fatness remains uncertain. Objective: The objective of the study was to investigate associations of dietary variables and physical activity with body fatness in urban Chinese adults. Design: We conducted a cross-sectional study in 130 weight-stable men and women aged 35-49 y. Subjects were selected from upper and lower tertiles of dietary fat and physical activity on the basis of screening questionnaires. Dietary intake was assessed by weighed food intake, physical activity level (PAL) was calculated as the ratio of predicted total energy expenditure (TEE) to predicted resting energy expenditure, and body composition was measured with the use of [sup.2]H[sup.2]O. Reported energy intake and predicted TEE were validated against TEE determined with the use of [sup.2][H.sub.2][sup.18]O (n = 73). Results: Body fatness was positively associated with dietary variety (ie, variety of ingredients) (partial r = 0.186, P = 0.039) and frequency of consuming restaurant foods (partial r = 0.237, P = 0.001) and negatively associated with PAL (partial r = -0.307, P = 0.001) in a multiple regression analysis that controlled for sex and confounders. The combined variance accounted for by dietary variety and restaurant food consumption (9.1%) was equivalent to that for PAL (9.4%). Neither dietary fat nor energy density predicted body fatness, but dietary energy density predicted within-subject day-to-day variation in reported energy intake (P < 0.001). Conclusions: Dietary variety, frequency of restaurant food consumption, and PAL significantly predicted body fatness in urban Chinese adults, but dietary fat did not. These findings support previous studies in US adults and suggest that dietary variables other than fat have an important influence on adult body composition. KEY WORDS Physical activity level, dietary fat, energy density, dietary variety, restaurant food, body composition, doubly labeled water, China, adults

Background: The specific underlying causes of adult weight gain remain uncertain. Objective: The objective was to determine the association of 3 measures of eating behavior with weight gain and body mass index (BMI; in kg/[m.sup.2]) in adults. Design: Current dietary restraint, disinhibition, and hunger were assessed with the use of the Eating Inventory in 638 healthy, nonsmoking women aged 55-65 y. In addition, subjects reported their current weight and height, their weight for 6 age intervals, and changes in voluntary dietary energy restriction over the past 10 y. Current weight and height were validated in 10% of subjects. Results: Current disinhibition strongly predicted weight gain and current BMI (partial r = 0.27 and 0.34, respectively, both P < 0.001). Neither restraint nor hunger was a significant independent predictor of either variable, but the positive associations between disinhibition and both weight gain and BMI were attenuated by restraint (P = 0.016 and 0.010, respectively, after adjustment for confounding variables). In the subpopulation of women who reported a stable level of voluntary dietary energy restriction, disinhibition also strongly predicted weight gain and higher BMI, and restraint was negatively associated with weight gain (partial r = -0.17, P = 0.019). Conclusions: Higher disinhibition is strongly associated with greater adult weight gain and higher current BMI, and dietary restraint may attenuate this association when disinhibition is high. These findings suggest that eating behavior has an important role in the prevention of adult-onset obesity and that further studies are warranted. Am J Clin Nutr 2002;75:476-83. KEY WORDS Dietary restraint, disinhibition, body weight, BMI, obesity, overweight, postmenopausal women, body mass index, women

The effects of aging on energy requirements and energy balance have been studied by several research groups using the doubly labeled water method. The weight of evidence from these investigations suggests that current recommended dietary allowances underestimate the usual energy needs of adults of all ages, including older adults. In addition, doubly labeled water studies have found a significant negative association between body fatness and energy expenditure for physical activity, and a significant positive association between energy expenditure for physical activity and fat-free mass. Further studies are needed to refine estimates of energy requirements for different population groups and to address the role of physical activity in the prevention and treatment of obesity. Am J Clin Nutr 1998;68(suppl):975S-9S.

There remains controversy over the effects of dietary fat content on voluntary energy intake. Additionally, the question of whether there is a genetic susceptibility to overeating high-fat diets has not been resolved. To address these issues, we designed two diets: a low-fat diet providing [approximately equals] 20% of energy as fat and a high-fat diet with [approximately equals] 40% of energy as fat. The diets were matched for energy density, fiber, and palatability. In a two-phase, 18-d intervention study, voluntary energy intakes and macronutrient oxidation rates during the fasting and fed states were determined in seven pairs of identical male twins. In contrast with results of previous intervention studies, in which low-fat and high-fat diets were not matched for energy density and other associated variables, we observed no significant difference in voluntary energy intake between the low-fat and high-fat phases, and mean daily intakes were similar (10.3 and 10.7 MJ/d, respectively). Postprandial rates of fat oxidation tended to reflect fat intakes in the two dietary phases, thus helping to explain the lack of a difference in mean energy intakes. There was also a significant twin-pair similarity in differences in energy intakes between dietary phases (P = 0.013). These results suggest that dietary fat content does not have a major influence on voluntary energy intake when dietary variables usually associated with fat are controlled for and that there may be a familial influence on the effects of dietary fat content on energy intake.

We examined whether older individuals have an impairment in their ability to oxidize dietary fat, a factor that could help to explain age-associated weight gain. The subjects were 16 healthy younger and older women. Fat oxidation was determined by indirect calorimetry before and after consumption of four different test meals consumed [is greater than or equal to] 5 d apart. The intervention meals contained 0, 1046, 2092, or 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal, respectively), with 35% of energy from fat. The duration of each measurement was the amount of time required for postprandial energy expenditure to return to the premeal fasting value. A total of 96 measurements were obtained, including duplicates for all meal sizes in the younger women (in the follicular and luteal phases of the menstrual cycle). Total postprandial fat oxidation increased in proportion to meal size in the younger subjects, but did not increase above that for the 2092-kJ meal in the older women. In addition, older subjects had significantly lower total fat oxidation after consumption of the 4184-kJ meal (781 compared with 1029 kJ/measurement, P [is less than] 0.02) and also significantly greater fat deposition (745 compared with 464 kJ/measurement, P [is less than] 0.02). These findings suggest that, relative to younger women, older women have a reduced ability to oxidize dietary fat when they consume large meals.

The accuracy and precision of four different food intake assessment methods were evaluated in young and older women by comparing reported energy intakes with doubly labeled water measurements total energy expenditure (TEE). A study lasting 8 d was conducted in 10 young women aged 25.2 [+ or -] 1.1 y ([chi bar] [+ or -] SEM) and in 10 older women aged 74.0 t 1.4 y. Free-living TEE was measured over 7 d and food consumption was determined from weighed food intake data (7 d), a 24-h food recall (in duplicate), and two different food-frequency questionnaires [Fred Hutchinson Cancer Research Center (FHCRC)/Block and Willett, both in duplicate]. In addition, body composition was determined by using hydrodensitometry, and strenuous physical activity and the extent of dietary restraint were determined by questionnaire. In young women, 24-h recall gave mean energy intakes that were closest to measures of TEE (-0.34 [+ or -] 3.71 MJ/d compared with TEE, P = 0. 178), and energy intakes by food-frequency questionnaires were the only intake data that correlated significantly with individual values for TEE (P < 0.05). In older women, food-frequency questionnaires gave mean energy intakes that were closest to measured TEE (+0.53 [+ or -] 2.95 MJ/d with the Willett questionnaire and - 1.19 [+ or -] 3.02 MJ/d with the FHCRC/Block questionnaire). No energy intake data from this group correlated significantly with values for TEE. The 7-d weighed dietary intakes were significantly lower than measured TEE in both young and older women (-2.0 MJ/d in young and older women combined, P < 0.001), and did not correlate significantly with values for TEE, although they did most closely mirror the mean difference in TEE between the young and older women (2.30 MJ/d for TEE and 2.11 MJ/d for 7-d weighed intake). These data suggest that none of the methods studied gave accurate estimates of the usual energy requirements of individual subjects. In addition, the results suggest that for some types of studies, simple methods for assessing group mean dietary intake may actually give more accurate information than weighed dietary intakes. Am J Clin Nutr 1996;63:491-9.

There is little information on the effects of age on energy requirements in women. This issue was investigated in a cross-sectional study of 10 normal-weight young women aged 25.2 [+ or -] 1.1 y ([x, bar above] [+ or -] SEM) and 10 normal-weight older women aged 74.0 [+ or -] 1.4 y. In a 9-d study, measurements were made of free-living total energy expenditure (TEE) by using the doubly labeled water technique, body composition by using hydrodensitometry, and resting energy expenditure (REE) by using indirect calorimetry. Mean values for reported levels of strenuous activity were within the expected range in both groups (31 [+ or -] 13 min/d in the young group and 7 [+ or -] 2 min/d in the older group). Energy requirements expressed as the ratio of TEE to REE were 1.80 [+ or -] 0.10 and 1.62 [+ or -] 0.06 (P < 0.01) in the young and older group, respectively. When values for REE predicted from body weight (pREE) were used, as suggested in the current recommended dietary allowances (RDAs), the ratios of TEE to pREE in the two groups were 1.85 [+ or -] 0.10 and 1.54 [+ or -] 0.04 (P < 0.05). The RDAs significantly underpredicted the energy requirements of the young group (P < 0.05), but there was no significant underprediction in the older group. Although obtained in a relatively small number of subjects, these results provide no evidence to indicate that the current RDAs underestimate the energy requirements of older women, in contrast with previous observations of an underestimation of energy requirements by the RDAs in older men.

Background: Stunting increases the risk of obesity in developing countries, particularly in girls and women, but the underlying reason is not known. Objective: Our objective was to test the hypothesis that stunted children have lower energy expenditure than do nonstunted children, a factor that has predicted an increased risk of obesity in other high-risk populations. Design: A cross-sectional study was conducted in shantytown children from Silo Paulo, Brazil. Twenty-eight stunted children aged 8-11 y were compared with 30 nonstunted children with similar weight-for-height. Free-living total energy expenditure (TEE) was measured over 7 d by using the doubly labeled water method. In addition, resting energy expenditure (REE) was measured by indirect calorimetry and body composition was measured by dual-energy X-ray absorptiometry. Results: There were no significant associations between stunting and any measured energy expenditure parameter, including REE adjusted for weight ([bar]x [+ or -] SEM: 4575 [+ or -] 95 compared with 4742 [+ or -] 91 kJ/d, in stunted and nonstunted children, respectively) and TEE adjusted for weight (8424 [+ or -] 239 compared with 8009 [+ or -] 221 kJ/d, in stunted and nonstunted children, respectively). In multiple regression models that included fat-free mass and fat mass, girls had significantly lower TEE than did boys (P [is less than] 0.05) but not significantly lower REE (P = 0.17). Conclusions: There was no association between stunting and energy expenditure after differences between groups in body size and composition were accounted for. However, the girls had lower TEE than did boys, which may help to explain the particularly high risk of obesity in stunted adolescent girls and women in urban areas of developing countries. Am J Clin Nutr 2000;72:1025-31. KEY WORDS Energy requirements, children, stunting, developing countries, girls, obesity, shantytowns, Brazil

Background: Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms. Objective: We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children. Design: The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of Sao Paulo, Brazil. Twenty-eight were stunted (height-for-age z score [is less than] -1.5) and 30 had similar weight-for-height but normal height (height-for-age z score [is greater than] -1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry. Results: Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 [+ or -] 90 and 4755 [+ or -] 86 kJ/d, respectively; P = 0.14) and had normal postprandial thermogenesis (2.4 [+ or -] 0.3% and 2.0 [+ or -] 0.3% of meal load, respectively; P = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 [+ or -] 0.009 compared with 0.89 + 0.007; P = 0.04) and consequently, fasting fat oxidation was significantly lower (25 [+ or -] 2% compared with 34 [+ or -] 2% of energy expenditure; P [is less than] 0.01). Conclusions: Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries. Am J Clin Nutr 2000;72:702-7. KEY WORDS Fat oxidation, obesity, stunting, energy expenditure, children, metabolic rate, respiratory quotient, malnutrition, undernutrition, Brazil

Background: Factors affecting the accuracy of reported energy intake (rEI) need to be identified. Objective: Our objective was to investigate the association of psychological measures of eating behavior with the accuracy of rEI assessed by 7-d weighed intakes, a 24-h recall, and a food-frequency questionnaire. Design: Subjects were 26 restrained eaters aged 60.3 [+ or -] 0.6 y ([bar]x [+ or -] SEM) and weighing 63.8 [+ or -] 1.7 kg and 34 unrestrained eaters aged 59.4 [+ or -] 0.6 y and weighing 64.0 kg. rEI was assessed by using 3 dietary assessment methods and total energy expenditure (TEE) was determined by using doubly labeled water. Calculated EI (cEI) was determined as TEE corrected for the estimated change in body energy. Subjects completed the Eating Inventory. Results: rEI values were significantly lower than TEE values for all 3 dietary assessment methods (P [is less than] 0.05); there was no significant relation between rEI and TEE by any method. There was no significant difference in 100 x rEI:TEE between restrained and unrestrained eaters by any of the dietary assessment methods. When combined data from the 3 methods were used, 100 x rEI:cEI was not significantly different from 100% in unrestrained eaters (99 [+ or -] 6.8%) but was lower in restrained eaters (89.1 [+ or -] 5.3%; P [is less than] 0.05). There was a positive relation between hunger and 100 x rEI:TEE (P [is less than] 0.05). Conclusions: Low hunger is associated with undereating relative to normal eating during measurement of dietary intake; high dietary restraint may be associated with a reduction in reporting of consumed foods. Dietary hunger and restraint assessed with use of the Eating Inventory may help to identify subjects likely to underreport dietary intake. Am J Clin Nutr 2000;71:739-45. KEY WORDS Energy intake, total energy expenditure, psychological measures, weighed diet record, 24-h dietary recall, food-frequency questionnaire, dietary assessment, postmenopausal women

Background: Recent studies have questioned the accuracy of using the current recommended dietary allowances (RDAs) to predict usual energy requirements in adults. Objective: We developed equations to predict adult energy requirements from simple anthropometric and laboratory measures by using the doubly labeled water method to determine each subject's total energy expenditure (TEE), which is equal to usual energy requirements in weight-stable individuals. Design: This was a cross-sectional study conducted with 93 healthy, free-living adults [44 men and 49 women; body mass index range (in kg/[m.sup.2]): 18.4-31.8] aged 18-81 y. Body fat and fat-free mass were measured by underwater weighing, physical activity was estimated by using activity monitors, and resting energy expenditure was determined by indirect calorimetry. Information on anthropometric variables and reported strenuous activity was also collected. Results: Three regression equations were developed and verified for accuracy by using bootstrap analysis and doubly labeled water data published by other research groups. The first equation used information on only age, weight, height, and sex and had an SEE for prediction of TEE of 1.80 MJ/d. The second and third equations used different combinations of basic and laboratory data and had SEEs of 1.55 and 1.65 MJ/d, respectively. With use of the same analytic approaches, the RDAs for energy were shown to significantly underestimate usual energy needs by [approximately equals] 10%; the extent of underestimation was significantly greater for subjects with high TEEs than for subjects with low TEEs. Conclusion: Regression equations based on doubly labeled water measurements of TEE appear to be more accurate than the current RDAs for predicting energy requirements in healthy, nonobese adults living in affluent countries. Am J Clin Nutr 1999;69:920-6.

Background: Short-term experimental studies suggest that dietary variety may influence body fatness but no long-term human studies have been reported. Objective: The purpose of this study was to determine whether dietary variety within food groups influences energy intake and body fatness. Design: Seventy-one healthy men and women (aged 20-80 y), who provided accurate reports of dietary intake and completed a body-composition assessment, were studied. Results: Dietary variety was positively associated with energy intake within each of 10 food groups (r = 0.27-0.56, P [is less than] 0.05). In multiple regression analysis with age and sex controlled for, dietary variety of sweets, snacks, condiments, entrees, and carbohydrates (as a group) was positively associated with body fatness (partial r = 0.38, P = 0.001) whereas variety from vegetables was negatively associated (partial r = -0.31, P = 0.01) (R2 = 0.46, P [is less than] 0.0001). In separate models, both a variety ratio (variety of vegetables/variety of sweets, snacks, condiments, entrees, and carbohydrates) and percentage dietary fat were significant predictors of body fatness (controlled for age and sex, partial r = -0.39 and 0.31, respectively, P < 0.01). However, dietary fat was no longer significantly associated with body fatness when the variety ratio and dietary fat were included in the same model. Conclusions: Our data, coupled with those of previous short-term studies, suggest that a high variety of sweets, snacks, condiments, entrees, and carbohydrates coupled with a low variety of vegetables promotes long-term increases in energy intake and body fatness. These findings may help explain the rising prevalence of obesity. Am J Clin Nutr 1999;69:440-7. KEY WORDS Dietary variety, dietary fat, dietary composition, body composition, obesity, energy intake, adults, vegetables