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It is estimated that more than 170 million people are infected with hepatitis C virus (HCV) worldwide (1,2). Clinical trials have demonstrated that, for the first time in human history, [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jada.2009.10.003 Byline: Lorien E. Urban, Gerard E. Dallal, Lisa M. Robinson, Lynne M. Ausman, Edward Saltzman, Susan B. Roberts Abstract: The accuracy of stated energy contents of reduced-energy restaurant foods and frozen meals purchased from supermarkets was evaluated. Measured energy values of 29 quick-serve and sit-down restaurant foods averaged 18% more than stated values, and measured energy values of 10 frozen meals purchased from supermarkets averaged 8% more than originally stated. These differences substantially exceeded laboratory measurement error but did not achieve statistical significance due to considerable variability in the degree of underreporting. Some individual restaurant items contained up to 200% of stated values and, in addition, free side dishes increased provided energy to an average of 245% of stated values for the entrees they accompanied. These findings suggest that stated energy contents of reduced-energy meals obtained from restaurants and supermarkets are not consistently accurate, and in this study averaged more than measured values, especially when free side dishes were taken into account. If widespread, this phenomenon could hamper efforts to self-monitor energy intake to control weight, and could also reduce the potential benefit of recent policy initiatives to disseminate information on food energy content at the point of purchase. Article History: Accepted 24 November 2008

Calorie restriction (CR) enhances immune response and prolongs life span in animals. However, information on the applicability of these results to humans is limited. T-cell function declines with age. We examined effects of CR on T-cell function in humans. Forty-six overweight, nonobese participants aged 20-42 years were randomly assigned to 30% or 10% CR group for 6 months. Delayed-type hypersensitivity (DTH), T-cell proliferation (TP), and prostaglandin [E.sub.2] ([PGE.sub.2]) productions were determined before and after CR. DTH and TP to T-cell mitogens were increased in both groups over baseline (p [less than or equal to] .019). However, number of positive responses to DTH antigens (p = .016) and TP to anti-CD3 reached statistical significance only alter 30% CR (p = .001). Lipopolysaccharide-stimulated [PGE.sub.2] was reduced in both groups but reached statistical significance after 30% CR (p [less than or equal to] .029). These results, for the first time, show that 6-month CR in humans improves T-cell function. Key Words: Calorie restriction--T cell--Immune response--Aging--Obesity. doi: 10.1093/gerona/glp101

Exercise has well-recognized health benefits, including reduction in risk factors for cardiovascular disease and type 2 diabetes. However, the extent to which exercise influences energy regulation and facilitates a reduction in body fat is less clear. This review summarizes published studies on the effects of different amounts of exercise on body fatness, energy intake, and food preferences in humans. The results show consistent effects of exercise on body fatness in the absence of prescribed dietary change, with a progressive loss of body fat associated with higher exercise energy expenditures in both men and women. In part, these effects appear to be mediated by a spontaneous reduction in hunger associated with participation in exercise. Insufficient data are available on whether there are changes in food preferences and taste perception that influence energy balance through macronutrient selection, so further studies in this area are needed. doi: 10.1301/nr.2007.jan. 1-19 Key words: body composition, energy intake, exercise, food palatability, macronutrient

There is considerable uncertainty over whether any one dietary pattern broadly facilitates weight loss or maintenance of weight loss, and current dietary guidelines recommend a spectrum of dietary composition for the general population. However, emerging evidence suggests that specific dietary compositions may work better for identifiable groups of overweight/ obese individuals based on their individual metabolic status. In particular, characteristics of insulin dynamics, such as insulin sensitivity or insulin secretion status, may interact with diets that vary in macronutrient composition to influence the weight loss achieved with a hypocaloric diet. Key words: dietary composition, insulin secretion, insulin sensitivity, weight loss

Background. The association of psychological eating behavior constructs with overweight and obesity during early adult life and middle age has been documented ill several studies. However, the association of eating behavior with unexplained weight change in old age is relatively unexplored. Methods. Body weight, eating behavior (dietary restraint, disinhibition, and hunger as assessed by the Eating inventory), reported dietary intake, and physical activity level were assessed at baseline in 36 nonobese postmenopausal women aged 61.3 [+ or -] 3.1 years (mean + standard deviation). Measurements were repeated 4.4 [+ or -] 0.9 years later, and changes in body weight were examined in relation to baseline and follow-up eating behavior scores, reported dietary intake, and physical activity level. Results. Participants had no major changes in health or lifestyle characteristics over the study interval. Weight change ranged from -7.5 to + 5.8 kg (mean-0.3 [+ or -] 3.5 kg), and there were no significant changes in reported dietary intake. Mean hunger score (calculated as the mean of baseline and follow-up hunger score) predicted weight change per year over the study period (bivariate r = 0.386, p = .020), even in statistical models adjusted for mean dietary intake variables (partial r = 0.658, p = .003). Restraint, disinhibition, and physical activity level did not predict weight change. Conclusions. Reported hunger assessed by the Eating Inventory was associated with unintentional weight change in healthy postmenopausal women. The Eating Inventory questionnaire may provide a clinically useful tool for identifying older individuals at risk of undesirable weight change, and particularly unintentional weight loss, a factor strongly associated with increased morbidity and premature death in this population.

I. Introduction II. Changes in the Regulation of Energy Intake A. Comparisons of young and elderly adults B. Reduced hunger and increased satiation as mediators of impaired defense against energy [...]

Objective To examine relative associations of dietary composition variables with body mass index (BMI; calculated as kg/[m.sup.2]) among young and middle-aged US adults. We hypothesized that in subjects with physiologically plausible reported energy intakes, fiber intake would be inversely associated with BMI, independent of other dietary composition and sociodemographic variables. Subjects and design Data from adults age 20 to 59 years in the Continuing Survey of Food Intakes by Individuals (CSFII) 1994-1996 were used. Exclusions were pregnancy or lactation, food insecurity, missing weight or height data, or having only one dietary recall. Based on our previously published methods, a physiologically plausible reported energy intake was calculated as being within [+ or -]22% of predicted energy requirements for the mean of two 24-hour recalls. Results Reporting plausibility ([reported energy intake / predicted energy requirements] X 100) averaged 83% in the total sample (N = 4,539) and increased to 96% in the plausible sample (n = 1,932). Only approximately 5% of the plausible sample consumed the Adequate Intake for fiber. In plausibly reporting women, fiber, its interaction with percentage energy from fat, and energy density were independently associated with BMI. Only percentage energy from fat was associated with BMI in men reporting plausibly. Compared with the total sample, stronger relationships between diet and BMI were observed among the plausible reporters. In women, a low-fiber (<1.5 g/MJ*), high-fat ([greater than or equal to]35% energy) diet was associated with the greatest increase in risk of overweight or obesity compared with a high-fiber, low-fat diet. Conclusions Weight control advice for US women should place greater emphasis on consumption of fiber. J Am Diet Assoc. 2005;105:1365-1372.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jada.2005.06.001 Byline: Nancy C. Howarth, Terry T.-K. Huang, Susan B. Roberts, Megan A. McCrory Abstract: To examine relative associations of dietary composition variables with body mass index (BMI; calculated as kg/m.sup.2) among young and middle-aged US adults. We hypothesized that in subjects with physiologically plausible reported energy intakes, fiber intake would be inversely associated with BMI, independent of other dietary composition and sociodemographic variables. Article Note: (footnote) At the time of the study, N. C. Howarth was a doctoral candidate, T. T.-K. Huang was a postdoctoral research associate, and M. A. McCrory was a scientist II, Energy Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA.

Background. Low body mass index (BMI) and micronutrient deficiencies are associated with increased morbidity and mortality rates in old age. Whether adverse patterns of dietary variety predict both low BMI and low micronutrient intakes in older adults was investigated. Methods. A cross-sectional analysis of national survey data was conducted in 1174 healthy adult men and women (ages 21 to 90 years) who provided physiologically plausible dietary data in the 1994-1996 Continuing Survey of Food Intakes by Individuals. Measurements included reported energy intake, protein intake (percentage meeting Recommended Dietary Allowance), micronutrient intakes (percentage meeting Estimated Average Requirements for 14 micronutrients), and BMI. Results. Adults who were 61 years or older consumed a greater total variety of foods, chose foods from a wider range of food groups, had a greater variety of micronutrient-dense foods and energy-weak foods, and had a lower variety of micronutrient-weak foods compared with adults ages 21 to 60 years (p < .05 to .001). However, older adults with low BMIs ( Conclusions. In contrast to previous suggestions that older persons consume a monotonous diet, this study showed that adults who were 61 years or older consumed a greater total food variety, and a greater variety of micronutrient-dense and energy-weak foods, compared with adults who were 60 years or younger. Although consumption of a low variety of energy-dense foods may contribute to reduced energy intake and body weight at any age, the variety of micronutrient-dense foods consumed needs to increase in old age to prevent micronutrient deficiencies. These findings suggest that all adults need advice on the changing needs for dietary variety with aging to maintain health, and that older persons with low BMI are particularly vulnerable to dietary shortfalls.

The relative contribution of circulating glucose to meal-to-meal variability in energy intake is not known. In 8 free-living young (median age 26.5 y) women with healthy body weight (median BMI 22.2 kg/[m.sup.2]), we measured glucose in the interstitial space by an automated monitoring procedure (continuous glucose monitoring system, CGMS[TM]) for up to 3 consecutive days (mean 706 glucose readings per subject). We examined the association between interstitial glucose (which lags blood glucose by ~10 min), self-reported hunger, satiety, desire for a meal, and nutrient intakes. Participants reported consuming a typical Western diet (59% carbohydrate, 27% fat, 14% protein). Median (interquartile range) interstitial glucose was 5.2 mmol/L (4.7-5.8). Using repeated-measures techniques in univariate analyses, desire for a meal (r = 0.45, P < 0.0001), hunger (r = 0.37, P = 0.0002), satiety (r = -0.40, P < 0.0001), low interstitial absolute mean glucose up to 25 min before eating (r = -0.23, P = 0.02), and a large decline in glucose between 40 and 5 min before eating (r = -0.17, P = 0.08) were all associated with meal energy intake. In multivariate regression analyses, desire for a meal (P < 0.0001) and hunger (P = 0.02) were the strongest independent contributors to meal energy intake, whereas absolute mean glucose measured in the period 15 to 0 min before eating was marginally significant (P = 0.08). In conclusion, absolute glucose level is a significant predictor of energy intake in nonobese women. However, desire for a meal and hunger are quantitatively more important, emphasizing the importance of both glucose signals and nonglucose (internal or environmental) factors in within-subject variability in energy intake. In addition, the CGMS may have utility in understanding the role of circulating glucose in energy regulation in free-living subjects under a wide range of different nutritional conditions. KEY WORDS: * glucose * energy * hunger * satiety * free-living

To test the hypothesis that total energy expenditure (TEE) and resting energy expenditure (REE) are low in extremely obese individuals, factors that could contribute to maintenance of excess weight, a cross-sectional study was conducted in 30 weight stable, extremely obese women [BMI (mean [+ or -] SEM) 48.9 [+ or -] 1.7 kg/[m.sup.2]]. TEE was measured over 14 d using the doubly labeled water method, REE and the thermic effect of feeding (IEF) were measured using indirect calorimetry, and activity energy expenditure (AEE) was calculated as TEE--(REE + TEF). Body composition was determined using a 3-compartment model. Subjects were divided into tertiles of BMI (37.5-45.0; 45.1-52.0; and 52.1-77.0 kg/[m.sup.2]) for data analysis. TEE and REE increased with increasing BMI tertile: TEE, 12.80 [+ or -] 0.5, 14.67 [+ or -] 0.5, and 16.10 [+ or -] 0.9 MJ/d (P < 0.01); REE, 7.87 [+ or -] 0.2, 8.78 [+ or -] 0.3, and 9.94 [+ or -] 0.6 MJ/d (P < 0.001), and these values were 29-38% higher than published means of measured TEE in nonobese individuals. No significant differences were observed among BMI tertiles for AEE, TEF, or physical activity level (PAL = TEE/REE, overall mean 1.64 [+ or -] 0.16). The Harris-Benedict and WHO equations provided the closest estimates of REE (within 3%), whereas the obese-specific equations of Ireton-Jones overpredicted (40%) and Bernstein underpredicted (21%) REE. Extremely obese individuals have high absolute values for TEE and REE, indicating that excess energy intake contributes to the maintenance of excess weight. Standard equations developed for nonobese populations provided the most accurate estimates of REE for the obese individuals studied here. REE was not accurately predicted by equations developed in obese populations. J. Nutr. 134: 1412-1416, 2004. KEY WORDS: * extreme obesity * energy expenditure * fat-free mass * prediction equations

To identify existing dietary patterns and examine associations between these patterns and plasma homocysteine and B vitamin concentrations in an urban Chinese population living in Beijing (n = 119), dietary information was collected with a food frequency questionnaire designed for this population. Plasma homocysteine and B vitamin concentrations were examined. Food group variables, expressed as percentages of total energy intake, were entered into cluster analysis to define three distinct dietary pattern groups. The prevalence of high homocysteine (>11 [micro]mol/L for women and 12 [micro]mol/L for men), was 31.9%; of low folate ( KEY WORDS: * dietary patterns * homocysteine * B vitamin * cluster analysis * Chinese

Little is known about the relative effects of fermentable fiber (FF) vs. nonfermentable fiber (NFF) on energy regulation in humans. We compared 27 [+ or -] 0.6 g/d supplements of FF (pectin,/[beta]-glucan) and NFF (methylcellulose) for their ability to decrease ad libitum energy intake (El) and hunger, increase satiety and cause spontaneous body weight and fat losses. Men and women (n = 11) aged 23-46 y, BMI 20.0-34.4 kg/[m.sup.2], consumed first NFF and then FF for 3 wk each, with a 4-wk washout period between phases. Daily satiety assessed with analog scales was higher with NFF than FF (60.7 [+ or -] 1.0 vs. 57.7 [+ or -] 0.8 mm, P = 0.01). However, there were no differences in reported El (NFF < FF by 7%, P = 0.31, NFF < baseline by 9.5%, P = 0.11), body weight (NFF 0.13 kg, P = 0.73; FF 0.13 kg, P = 0.60) or fat percentage (NFF -0.3%, P = 0.56; FF -0.1%, P = 0.66) within either phase. In contrast to findings in animals, NFF was more, rather than less satiating than FF, and use of neither NFF nor FF preparations was associated with body weight or fat loss. These pilot results suggest no role for short-term use of FF and NFF supplements in promoting weight loss in humans consuming a diet ad libitum. J. Nutr. 133: 3141-3144, 2003. KEY WORDS: * fiber * fermentable * nonfermentable * satiety * weight loss

Body composition methods were examined in 20 women [body mass index (BMI) 48.7 [+ or -] 8.8 kg/[m.sup.2]] before and after weight loss [-44.8 [+ or -] 14.6 (SD) kg] after gastric bypass (GBP) surgery. The reference method, a three-compartment (3C) model using body density by air displacement plethysmography and total body water (TBW) by [H.sub.2][sup.18]O dilution (3C-[H.sub.2][sup.18]O), showed a decrease in percent body fat (%BF) from 51.4 to 34.6%. Fat-free mass hydration was significantly higher than the reference value (0.738) in extreme obesity (0.756; P < 0.001) but not after weight reduction (0.747; P = 0.16). %BF by [H.sub.2][sup.18]O dilution and air displacement plethysmography differed significantly from %BF by 3C-[H.sub.2][sup.18]O in extreme obesity (P < 0.05) and 3C models using [sup.2][H.sub.2]O or bioelectrical impedance analysis (BIA) to determine TBW improved mean %BF estimates over most other methods at both time points. BIA results varied with the equation used, but BIA better predicted %BF than did BMI at both time points. All methods except BIA using the Segal equation were comparable to the reference method for determining changes over time. A simple 3C model utilizing air displacement plethysmography and BIA is useful for clinical evaluation in this population. three-compartment models

Obesity, cardiovascular disease, and type 2 diabetes mellitus are now prevalent among adults living in developing countries; these chronic diseases affect socioeconomically disadvantaged adults living in impoverished families with undernourished children. This review summarizes data from Brazil--a developing country undergoing the nutrition transition--suggesting an association between childhood undernutrition and obesity and chronic degenerative disease. Potential mechanisms for the association include long-term effects of childhood undernutrition on energy expenditure, fat oxidation, regulation of food intake, susceptibility to the effects of high-fat diets, and altered insulin sensitivity. The combination of childhood undernutrition and adult chronic degenerative disease results in enormous social and economic burdens for developing countries. Further research is urgently needed to examine the effect of childhood undernutrition on risk of obesity and chronic degenerative diseases; one goal of such research would be to determine and provide low-cost methods for prevention and treatment. Key Words: undernutrition, stunting, obesity, diabetes, hypertension

U.S. adults are now gaining more weight and becoming obese at an earlier age than in previous years. The specific causes of adult weight gain are unknown, but may be attributed to a combination of factors leading to positive energy balance. U.S. food supply data indicate that Americans have had a gradual increase in energy intake since 1970, and that per capita energy intake was 1.42 MJ/d (340 kcal/d) higher in 1994 than that in 1984. In contrast, self-reported physical activity remained constant between 1990 and 1998. Taken together, these data indicate that the increasing trend in U.S. adult weight gain is primarily attributable to overconsumption of energy. Epidemiological and experimental studies in animals and humans provide strong evidence that biobehavioral factors such as dietary variety, liquid (vs. solid) energy, portion size, palatability (taste), snacking patterns, restaurant and other away-from-home food, and dietary restraint and disinhibition influence hunger, satiety and/or voluntary energy intake. When these eating behaviors are consistently experienced either separately or in combination over the long term, they are likely to facilitate overeating. We provide a brief overview of the evidence to date for the role of these biobehavioral factors in contributing to excess energy intake and increases in body weight over time. J. Nutr. 132: 3830S-3834S, 2002. KEY WORDS: * obesity * weight gain * energy intake * energy balance * biobehavioral factors

Recommendations for increased consumption of protein are among the most common approaches of popular or fad diets. This review summarizes the effects of dietary protein on satiety, energy intake, thermogenesis, and weight loss, as well as its effect on a variety of health outcomes in adults. In short-term studies, dietary protein modulates energy intake via the sensation of satiety and increases total energy expenditure by increasing the thermic effect of feeding. Whereas these effects did not contribute to weight and fat loss in those studies in which energy intake was fixed, one ad libitum study does suggest that a high-protein diet results in a greater decrease in energy intake, and therefore greater weight and fat loss. In terms of safety, there is little long-term information on the health effects of high-protein diets. From the available data, however, it is evident that the consumption of protein greater than two to three times the U.S. Recommended Daily Allowance contributes to urinary calcium loss and may, in the long term, predispose to bone loss. Caution with these diets is recommended in those individuals who may be predisposed to nephrolithiasis or kidney disease, and particularly in those with diabetes mellitus. Key Words: dietary protein, energy intake, thermogenesis, weight loss, high-protein diet, urinary calcium loss, bone loss

Background. Although an influence of eating behavior on dietary intake and physiology has been documented in several studies, the extent to which eating behavior influences long-term health is uncertain. Methods. Current dietary restraint, disinhibition, and hunger were assessed using the Eating Inventory in 1252 nonsmoking women aged 55 to 65 years. In addition, subjects reported the presence or absence of 22 specific morbidities, along with general demographic information. Logistic regression was used to examine associations between eating behavior scores and morbidity, adjusting for age, prior smoking status, hormone replacement therapy, education level, and body mass index (BMI). Results. In adjusted models excluding BMI, higher disinhibition scores were associated with small increased risks for hypercholesterolemia (odds ratio [OR] 1.04, p = .045), leg cramps (OR 1.05, p = .044), indigestion (OR 1.06, p = .020), and cataract (OR 1.09, p = .036), and a decreased risk of eczema (OR 0.91, p = .008). In addition, higher hunger scores were associated with increased risk of eczema (OR 1.09, p = .026). However, after adjusting for confounding variables plus BMI, higher disinhibition scores were associated with increased risks for low back pain (OR 1.06, p = .031) and constipation (OR 1.10, p = .004), and associations of disinhibition and hunger with eczema were unchanged (OR 0.90, p = .008 and OR 1.09, p = .024, respectively). Dietary restraint was not associated with morbidity in any model. Conclusions. Higher disinhibition and hunger scores were associated with small alterations in reported morbidity risk in a large population of nonsmoking older women. Although our cross-sectional study design makes the directionality of these relationships unclear, our results suggest at most a relatively minor independent influence of eating behavior constructs on long-term health.

There is little information on the accuracy of simple body composition methods in non-Western populations. We determined the percentage of body fat (%BF) by isotope dilution [oxygen-18 ([H.sub.2][sup.18]O) and deuterium oxide ([sup.2][H.sub.2]O)] and anthropometry in 71 healthy, urban Chinese adults aged 35-49 y [body mass index (BMI) 18-35 kg/[m.sup.2]]. The accuracy of several prediction equations for assessment of %BF from skinfold measurements was evaluated against %BF determined by [H.sub.2][sup.18]O dilution. We also assessed the relationship between BMI and %BF, and the fat-free mass (FFM) hydration coefficient for our population. All skinfold equations yielded means within ~2%BF of [H.sub.2][sup.18]O-derived %BF. However, on the basis of residual plot analysis and the 95% confidence interval (Cl) for the mean difference between methods, the equations of Durnin and Womersley (for assessment of body density from skinfolds) coupled with that of Brozek et al. (for assessment of %BF from body density) provided the most valid assessment for individuals. In addition, the FFM hydration coefficient averaged 0.734 [+ or -] 0.002 (SEM), indicating that the usually assumed value of 0.732 is appropriate for this population. Finally, although BMI had high specificity (90%) for classifying individuals as having body fat within the normal range (30%BF. J. Nutr. 132: 310-317, 2002. KEY WORDS: * isotope dilution * anthropometry * body mass index * percentage of body fat * fat-free mass hydration coefficient

Research has been conducted on the high-glycemic index carbohydrates. Results suggest that the consumption of these carbohydrates may increase hunger and promote overeating.

Research presented concerns the physiological aspects of unintentional weight loss in aging adults. Issues discussed concern biobehavioral and social factors that may impair the metabolism and regulation of food intake.

There remains controversy over the effect of age on postprandial thermogenesis, with some studies observing decreased postprandial thermogenesis in older subjects and other studies finding no effect of age. We investigated this issue in 8 young (25.2 [+ or -] 1.8 years) and 8 older (72.2 [+ or -] 2.1 years) healthy glucose-tolerant women with normal thyroid hormone status. Repeated measures of the thermic effect of feeding (TEF) were obtained following consumption of test meals containing 0, 1046, 2092, and 4184 kilojoules (kJ) by using indirect calorimetry. TEF at each meal size was determined once in the older subjects and twice in the younger subjects (during follicular and luteal phases of the menstrual cycle) for a total of 96 measurements. There was a positive dose-response between meal size and TEF (p < .001) that was not significantly affected by age group. The best single predictor of TEF expressed as a percentage of meal energy content was waist-to-hip ratio ([R.sup.2] = .416, p < .02). These results indicate that aging is not associated with decreased TEF in the absence of factors such as a hypothyroid state or glucose intolerance.

Information on the macronutrient composition of the diet is needed in doubly labeled water studies to convert measured rates of carbon dioxide production into values for total energy expenditure. There is no general consensus, however, about the best method to determine food intake for this purpose. Four common methods of measuring food intake (7-day weighed food intake, 24-hour recall, and Fred Hutchinson Cancer Research Center/Block and Willett food frequency questionnaires) were tested for their ability to provide comparable food quotient and total energy expenditure data in doubly labeled water studies in 10 young and 10 older women. All methods gave mean values for total energy expenditure that were within 1% of each other. Individual values obtained using the 24-hour recall and food frequency questionnaires were within +3% (standard deviation) of values determined using data from the 7-day weighed food record. These results suggest that it is not necessary to use time-consuming and expensive 7-day food records in doubly labeled water studies; instead, food intake data obtained more easily by 24-hour recall or food frequency questionnaire can provide comparable data. J Am Diet Assoc. 1998; 98:1015-1020., The doubly labeled water method is an isotopic method for determination of total energy expenditure (TEE) in free-living subjects (1,2). The method is based on measurement of the differential rates [...]

Blood glucose regulation in the fasting and fed states has important implications for health. In addition, the ability to maintain normal blood glucose homeostasis may be an important determinant of an individual's capacity to regulate food intake. We tested the hypothesis that aging is associated with an impairment in the ability to maintain normal blood glucose homeostasis following the consumption of large meals but not small ones, a factor that could help to explain age-related impairments in the control of food intake and energy regulation. The subjects were eight healthy younger women (25 f [+ or -] years, SD) and eight healthy older women (72 [+ or -] 2 years) with normal body weight and glucose tolerance. Following a 36-h period when diet and physical activity were controlled, subjects consumed test meals containing 0, 1046, 2092, and 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal), with 35% of energy from fat, 48% from carbohydrate, and 17% from protein. Each subject consumed each of the test meals on a separate occasion. Serial blood samples were collected at baseline and during 5 h after consumption of the meals. Measurements were made of circulating glucose, insulin, glucagon, free fatty acids, and triglycerides. There was no significant difference between young and older women in their hormone and metabolite responses to fasting and consumption of the 1046-kJ meal However, following consumption of 2092 and 4148 kJ, older individuals showed exaggerated responses and a delayed return to premeal values for glucose (p = .023), insulin (p = .010), triglycerides (p = .023), and the ratio of insulin to glucagon (p = .026). In conclusion, these results suggest an impairment in the hormonal and metabolite responses to large meals in older women.

The effects of fat-modified foods or low-fat diets will only have a slight effect on obesity. Fat replacement or reductions are only one part of a broader scheme that must involve lifestyle modification. Consumers who use fat-modified foods consistently over many years may witness a impact toward recommended dietary goals.

Previous studies by our group and others have suggested that nutritional stunting may increase the risk of obesity. To investigate mechanisms that could explain a link between stunting and obesity, a 22-mo follow-up study was conducted in two groups of shantytowns school girls (7-11 y old) in Sao Paulo, Brazil. One group (n = 15) had mild stunting (defined using a cutoff of -1.4 Z-scores of height-for-age) but normal weight-for-height; the control group (n = 15) had normal weight and height. Similar energy intake, dietary macronutrient composition and energy expenditure were observed in the two groups. Both groups showed comparable levels of IGF-1 that were below the normal range. A significant and positive association between baseline IGF-1 and the change in height-for-age during follow-up was found in all subjects combined (P = 0.044). A significant association was found between the baseline percentage of dietary energy supplied by fat and the gain in weight-for-height during follow-up in girls with mild stunting (P = 0.048), but not in the nonstunted control girls (P = 0.245); however, the slopes of these relationships were not significantly different. This study raises the question of whether a diet high in fat may increase the susceptibility to excess body fat gain in children who are mildly stunted. Further studies are need to explore this issue and to examine the possible etiological role of low levels of IGF-1. KEY WORDS: stunting; malnutrition; obesity; body composition

Relatively little is known about the influence of age on energy regulation during energy imbalance. We compared the effects of underfeeding on changes in energy expenditure, substrate oxidation, and body energy loss between young men (age 22.0 [+ or -] 0.9 [SEM] years) and older men (age 66.0 [+ or -] 1.8) who were leading unrestricted lives. Changes in total energy expenditure (TEE), resting energy expenditure (REE), the thermic effect of feeding (TEF), respiratory quotient, and body energy loss were determined in response to undereating by 3.17 [+ or -] 0.16 Megajoule (MJ)/day for 21 days in 19 healthy subjects consuming a typical diet. No significant effects of age were observed in changes in TEE, REE, TEF, or body energy loss in response to underfeeding. Thus, older men do not appear to have any impairment of energy conservation during negative energy balance compared to young men. This normal pattern of energy conservation during undereating together with the previously demonstrated reduction in energy dissipation during overeating can be predicted to promote body fat deposition in older men during the cycles of positive and negative energy balance that occur during normal life. This finding may help to explain the increased body fat mass in older individuals.

Relatively little is known about the influence of age on energy regulation during energy imbalance. We compared the effects of overfeeding on changes in energy expenditure, substrate oxidation, and energy deposition between young men (age 23.7 [+ or -] 1.1 [SEM] years) and older men(age70.0 [+ or -] 7.0) of normal body weight who were leading unrestricted lives. Changes in total energy expenditure, resting energy expenditure (REE), the thermic effect of feeding (TEF), respiratory quotient(RQ), and body energy content were determined in response to overeating by 4.09 [+ or -] 0.07 Megajoule (MJ)/day for 21 days in 16 healthy subjects consuming a typical diet. After excluding data from one young subject with unusual results and adjusting for individual differences in excess energy intake, there was a tendency towards a smaller increase in REE in older men compared to the young men (p = .07) which was accounted for by their lower fat-free mass (p = .016). There was also a significantly smaller increase in resting energy expenditure averaged over fasting and fed states (i.e, REE [+ or -] TEF) with overfeeding in order men than in young men (p < .01). Combined, these smaller increases in energy expenditure with overfeeding in the older subjects averaged an estimated 365 kilojoule (kj)/day (8.9% of the excess energy intake) (p

Genetic abnormalities found in both animal and human research may contribute to obesity. Researchers have identified three obesity genes in mouse models, the agouti protein, the Ob protein, and the fat gene. In contrast, genetic evidence in human obesity seems to be much more complex. Possible contributing factors to total body fat include DNA variations of apolipoproteins, uncoupling protein, adrenergic receptors, and lipoprotein lipase. Five human genes may be linked to abdominal fat accumulations. Fat deposits in certain parts of the body has also been linked to DNA polymorphisms, such those for insulin, apolipoproteins, and adrenergic receptors.

Controversy continues on the role of energy expenditure in regulating energy in human beings. It has been seen that energy expenditure contributes to energy regulation in normal individuals and also to the deregulation of energy balance that distinguishes obesity. An apparent equilibration between physical activity and body fat content due to a direct influence of physical activity on the metabolic determinants of energy balance is also suggested.

Older men who overeat or undereat for a period of time may lose their ability to regulate caloric intake. Researchers studied 17 healthy men who were in their early 20s and 18 healthy men in their 70s. For a period of 21 days, seven young men and nine older men were overfed while 10 younger men and 9 older men were underfed. Changes in body composition, weight, and caloric intake were recorded during the over- or underfeeding period and 46 days subsequently. After the overfeeding period, young men ate less than their bodies required for weight maintenance and their body weight decreased rapidly. Older men, however, continued to exceed their body's caloric requirements for weight maintenance and they did not lose the weight gained during overfeeding. After underfeeding, young men ate more food than their bodies required for weight maintenance. At the end of the study, these men actually weighed more than they did at the study onset. After underfeeding, older men continued to consume fewer calories than their bodies required. They failed to regain their normal body weight by the end of the study., Objective. - To investigate the effects of aging on mechanisms of body energy regulation and thereby determine the causes of unexplained weight loss in older persons, a factor predisposing to premature death and disability. Design. - Dietary intervention study. Setting. - Metabolic ward and outpatient. Participants. - The subjects were 35 healthy younger and older men of normal body weight consuming a diet of typical composition and performing usual activities. Main Outcome Measures. - Subjects were either overfed by a mean ([+ or -] SD) of 4.09 ([+ or -] 0.26) MJ/d (n=17) or underfed by 3.17 ([+ or -] 0.68) MJ/d (n=18) for 21 days. Measurements were made of changes in body weight, body composition, and energy expenditure during overfeeding or underfeeding, and of subsequent voluntary nutrient intakes and changes in body weight. Results. - There was no significant effect of aging on changes in body composition, body weight, or energy expenditure with overfeeding or underfeeding. However, following overfeeding, younger men exhibited spontaneous hypophagia, whereas the older men did not (mean [[+ or -] SD] changes in energy intake relative to control values were -2.11 [[+ or -] 2.18] and 1.55 [[+ or -] 2.11] MJ/d, respectively; P=.006). As a result,the younger men lost the excess body weight gained during overfeeding but the older men did not. Similarly, following underfeeding, the younger men exhibited hyperphagia while the older men did not (mean [[+ or -] SD] changes in energy intake relative to control values were 1.88 [[+ or -] 2.31] and -0.52 [[+ or -] 1.54] MJ/d, respectively; P=.02), and as a result the older men failed to regain the weight lost during underfeeding. Conclusions. - These results in 35 men suggest that aging may be associated with a significant impairment in the ability to control food intake following overeating or undereating. since overeating and undereating occur routinely as part of the normal pattern of energy regulation, the findings reported herein may help to explain the vulnerability of older persons to unexplained weight gain and weight loss. (JAMA. 1994;272:1601-1606)

High-intensity resistance exercise training may improve the muscle strength and mass and decrease frailty in elderly people. In a study of 100 frail nursing home residents aged 72 to 98, an experimental group performed high-intensity progressive resistance exercises of the hip and knee muscles for 10 weeks and also consumed a nutritional supplement. Muscle strength measurements, including gait velocity, stair-climbing ability, and overall physical activity, improved in the experimental group, but not in a group performing placebo activities such as aerobic or flexibility exercises. The nutritional supplement was not found to have an effect, either positive or negative. The results of the study suggest that the musculoskeletal system of the elderly person can overcome previous disuse when challenged by resistance training, and can realize significant improvement in mobility and overall activity.

We investigated the importance of adaptive variations in energy expenditure in the regulation of energy balance in young and elderly men of normal body weight leading unrestricted lives. Changes were measured in total and resting energy expenditure and body composition in response to overeating by approximately 4.2 MJ/d or undereating by 3.3 MJ/d for 21 d in 39 young and elderly men consuming a typical diet. In the young men, an average of 85-90% of the excess energy intake during overeating was deposited. During underfeeding, mobilization of body energy compensated for an average of 65% of the energy deficit in these subjects. The resting metabolic rate, averaged for fasting and fed states, increased during overfeeding (+0.63 plus or minus 0.20 MJ/d, P < 0.01) and decreased during underfeeding (-0.42 plus or minus 0.12 MJ/d), but at least some of these changes were due to the obligatory expenditure associated with nutrient assimilation. There was no significant change in energy expenditure for physical activity or thermoregulation from overfeeding or underfeeding. Preliminary results indicate that aging had no effect on responses to overfeeding or underfeeding. These findings suggest that adaptive variations in energy expenditure are not the major determinant of energy regulation in young adults of normal body weight and that, instead, energy balance is maintained on a day-to-day basis through the control of nutrient intakes.

Dietary energy density (ED) has been suggested as an important determinant of energy intake and, therefore, energy regulation. This review summarizes published studies on the effects of dietary ED on hunger, satiety, energy intake, and body weight in healthy individuals, and compares the relative effects of ED manipulated by dietary fat only, fat and fiber, water, and type of sweetener. In short-term studies, consumption of low-ED foods promotes satiety, reduces hunger, and decreases energy intake with no marked differences between different dietary manipulations used to change ED. In addition, low-ED diets promote moderate weight loss in long-term studies. In studies lasting longer than 6 months, weight loss was more than three times as great in individuals consuming diets both low in fat and high in fiber compared with diets only low in fat (-3.4 kg versus -1.0 kg). Combined, these studies suggest that diets low in fat and high in fiber may be the most effective low-ED diets for promoting weight loss. Further research is needed on the effects of dietary ED by changing water or sweetener content.

The effect of aging on energy regulation remains controversial. We compared the effects of underfeeding on changes in energy expenditure and respiratory quotient in young normal weight men and women [YNW, age 25.7 [+ or -] 3.2 y(SD), body mass index (BMI) 23.1 [+ or -] 1.6 kg/[m.sup.2], young overweight men and women (YOW, age 26.1 [+ or -] 3.5 y, BMI 27.7 [+ or -] 2.1 kg/[m.sup.2]) and older (OLD) men and women (age 68.4 [+ or -] 3.3 y, BMI 27.4 [+ or -] 3.4 kg/[m.sup.2]). The thermic effect of feeding (TEF) during weight maintenance, and changes in resting energy expenditure (REE) and respiratory quotient were determined in response to undereating by an average 3.75 MJ/d for 6 wk. In addition, body composition was measured. No significant differences among the groups were observed in TEF, fasting and postprandial respiratory quotient, or the change in fasting respiratory quotient with underfeeding. However, REE adjusted for fat-free mass and fat mass was significantly lower in OLD subjects compared with YNW and YOW subjects (P [is less than] 0.05). In addition, the REE response to weight change was significantly attenuated in the OLD subjects (P = 0.023). These data suggest that the responsiveness of energy expenditure to negative energy balance is attenuated in old age, and provide further support for the hypothesis that mechanisms of energy regulation are broadly disregulated in old age. J. Nutr. 131: 1833-1838, 2001. KEY WORDS: * aging * energy metabolism * humans * respiratory quotient * body composition