Energy expenditure before and during energy restriction in obese patients

Twenty-four hour energy expenditure (24 EE), resting metabolic rate (RMR), spontaneous physical activity and body composition were determined in 7 obese patients (5 females, 2 males, 174 +/- 9% IBW, 38 +/- 2% fat mass) on 2 different occasions: before weight reduction, and after 10 to 16 weeks on a hypocaloric diet as outpatients, the recommended energy intake varying from 3500 to 4700 kJ/day depending on the subject. Mean body weight loss was 12.6 +/- 1.9 kg, ie 13% of initial body weight, 72% being fat. Twenty-four hour energy expenditure (24 EE) was measured in a respiration chamber with all the subjects receiving 10418 kJ/d before weight reduction and an average of 3360 +/- 205 kJ/d while on the diet. When expressed in absolute values, both 24 EE and RMR decreased during the hypocaloric diet from 9819 +/- 442 to 8229 +/- 444 and from 7262 +/- 583 to 6591 +/- 547 kJ/d respectively. On the basis of fat-free-mass (FFM), 24 EE decreased from 168 +/- 6 to 148 +/- 5 kJ/kg FFM/d whereas RMR was unchanged (approximately 120 kJ/kg FFM/d). Approximately one half of the 24 EE reduction (1590 kJ/d) was accounted for by a decrease in RMR, the latter being mainly accounted for by a reduction in FFM. Most of the remaining decline in 24 EE can be explained by a decreased thermic effect of food, and by the reduced cost of physical activity mainly due to a lower body weight. Therefore, there seems little reason to evoke additional mechanisms to explain the decline in energy expenditure during dieting.     

Energy metabolism in humans at a lowered ambient temperature

OBJECTIVE: Assessment of the effect of a lowered ambient temperature, ie 16 degrees C (61 degrees F), compared to 22 degrees C (72 degrees F), on energy intake (EI), energy expenditure (EE) and respiratory quotient (RQ) in men. DESIGN: Randomized within-subject design in which subjects stayed in a respiration chamber three times for 60 h each, once at 22 degrees C, and twice at 16 degrees C, wearing standardized clothing, executing a standardized daily activities protocol, and were fed in energy balance (EBI): no significant difference between EE and EI over 24 h). During the last 24 h at 22 degrees C, and once during the last 24 h at 16 degrees C, they were fed ad libitum. SUBJECTS: Nine dietary unrestrained male subjects (ages 24+/-5 y, body mass index (BMI) 22.7+/-2.1 kg/m(2), body weight 76.2+/-9.4 kg, height 1.83+/-0.06 m, 18+/-5% body fat). RESULTS: At 16 degrees C (EB), EE (total 24 h EE) was increased to 12.9+/-2.0 MJ/day as compared to 12.2+/-2.2 MJ/day at 22 degrees C (P<0.01). The increase was due to increases in sleeping metabolic rate (SMR; the lowest EE during three consecutive hours with hardly any movements as indicated by radar): 7.6+/-0.7 vs 7.2+/-0.7 MJ/day (P<0.05) and diet-induced thermogenesis (DIT; EE-SMR, when activity induced energy expenditure as indicated by radar=0): 1.7+/-0.4 vs 1.0+/-0.4 MJ/day (P<0.01). Physical activity level (PAL; EE/SMR) was 1.63-1.68. At 16 degrees C compared to at 22 degrees C, rectal, proximal and distal skin temperatures had decreased (P<0.01). RQ was not different between the two ambient temperature situations. During ad libitum feeding, subjects overate by 32+/-12% (at 22 degrees C) and by 34+/-14% (at 16 degrees C). Under these circumstances, the decrease of rectal temperature at 16 degrees C was attenuated, and inversely related to percentage overeating (r(2)=0.7; P<0.01). CONCLUSION: We conclude that at 16 degrees C, compared to 22 degrees C, energy metabolism was increased, due to increases in SMR and DIT. Overeating under ad libitum circumstances at 16 degrees C attenuated the decrease in rectal core body temperature.     

Do obese eat faster than lean subjects? Food intake studies in Pima Indian men

Food intake rate has previously been derived from observation of eating behavior in laboratory settings or in public eating establishments. Although it has been suggested that obese individuals eat faster than lean individuals, observations of such an "obese eating style" have yielded mixed results. In the present study, the relationship between ad-libitum food intake rate and obesity was evaluated over 4 days on a metabolic ward in 28 healthy Pima Indian men (Mean +/- SD; 29 +/- 7 y, 100.4 +/- 27.1 kg, 33 +/- 10% body fat) using an automated food selection system containing a large variety of foods. Total energy intake averaged 18829 +/- 3299 kJ/d consisting of 47 +/- 4, 40 +/- 3, and 13 +/- 1 percent of carbohydrate, fat and protein, respectively. The average meal duration was 25 +/- 7 min. Food intake rate was 68 +/- 21 g/min while carbohydrate, fat and protein intake rates were 23 +/- 6, 9 +/- 3 and 6 +/- 2 g/min, respectively. Food intake rate correlated negatively with % body fat (r = -0.61, P < 0.01). Similar relationships were found between the intake rates of carbohydrate, fat and protein and body fatness. Only prospective studies will indicate whether a slow food intake rate may contribute to the etiology of obesity by possibly reducing satiety.     

Decreases in fasting leptin and insulin concentrations after acute energy restriction and subsequent compensation in food intake

BACKGROUND: The decrease in leptin after energy restriction is a starvation signal to the brain. Several studies have found an association between this decrease and subjective appetite; however, no solid data are available on the acute decrease in fasting leptin concentration and subsequent caloric compensation. OBJECTIVE: The objective was to assess the effect of acute decreases in fasting leptin concentrations, induced by energy restriction, on subsequent energy intake compensation. We hypothesized that men with a large decrease in fasting leptin concentrations would have larger ad libitum energy intakes than would men with a small decrease in leptin. DESIGN: Thirty-four male unrestrained eaters [age: 23 +/- 3 y; body mass index (in kg/m(2)): 22.3 +/- 1.6] participated in a semicontrolled intervention study. Fasting serum leptin and insulin concentrations were measured before and 2 d after 62% energy restriction. Energy intake was measured on the 2 following days on which food was provided ad libitum. RESULTS: During energy restriction, fasting leptin and insulin concentrations decreased by 27.2% (95% CI: -34.4%, -19.9%) and 30.7% (95% CI: -41.0%, -20.4%), respectively. Subjects consumed 143 +/- 27% of their estimated energy requirements (18.3 +/- 2.9 MJ) on the first day and 124 +/- 20% (16.0 +/- 2.6 MJ) on the second day of ad libitum intake. No significant correlations were observed between decreases in fasting leptin or insulin concentrations and subsequent ad libitum energy intake; however, decreases in insulin were correlated with an increase in carbohydrate intake (r=-0.49, P < 0.01). CONCLUSION: Although fasting leptin concentrations decreased significantly during energy restriction and subjects showed compensatory behavior during subsequent ad libitum food intake, no association was observed between the decrease in fasting leptin concentrations and caloric compensation.     

Body composition in mice maintained with cyclic periods of food restriction and refeeding

The effect of cyclic periods of underfeeding and overfeeding on body composition and energy efficiency was investigated in adult female CD1 Swiss mice. Four groups of mice were studied for 8 weeks: 1) Controls, fed stock diet ad libitum, 2) Overfed, fed stock diet plus a varied selection of highly palatable human foods (cafeteria feeding), 3) Cyclic-fed, given restricted amounts of stock diet (80% of controls) and cafeteria diet on alternate weeks, and 4) Restricted, fed 80% of the food consumed by the controls. The restricted mice had lower body weight, carcass energy content and energy expenditure than the other groups. The overfed mice had increased energy intake, energy expenditure, food efficiency, carcass fat and energy stores. The cyclic-fed mice had higher food intake than the controls but lower intake than the overfed mice. The cyclic-fed mice had increased food efficiency, increased carcass fat and carcass energy compared to the controls but values were less than for the overfed mice. Carcass energy was 224±8 kJ, controls; 314±18 kJ, overfed; 277±14 kJ, cyclic-fed and 173±9 kJ, restricted mice. Carcass energy was highly correlated with total energy consumed (r=0.592, p<0.001). Both regular and periodic consumption of an energy dense diet did increase energy intake, energy efficiency and carcass energy stores. However, there was no evidence that repeated periods of food restriction and refeeding increased body fat stores.     

Oral supplements differing in fat and carbohydrate content: effect on the appetite and food intake of undernourished elderly patients

BACKGROUND & AIMS: Since fat, relative to other macronutrients, has low satiety and high energy density, it may have therapeutic application for supplementing energy intake. This study compared the effect of isoenergetic (1050 kJ) high fat or high carbohydrate oral supplements, given at breakfast, on the short-term appetite and energy intake in undernourished elderly subjects. METHODS: Sixteen hospitalised, undernourished (body mass index: 20 +/- 3 kg/m2), elderly (77 +/- 8 yr) people were randomly allocated to a control or 1 of 2 supplement groups [fat: carbohydrate: protein (% energy) was 70:25:5 or 25:70:5]. In each group, energy intake (24-h food consumption) and appetite (visual analogue scales) were assessed over 3 consecutive days. RESULTS: Mean energy intake significantly (P = 0.0035) increased following supplementation: high fat 6973 kJ/d, high carbohydrate 6906 kJ/d vs. control 6079 kJ/d but mean voluntary 24-h energy intake remained unaffected. Compared to controls, supplemented subjects experienced reduced hunger (P = 0.07) between breakfast and lunch, but showed no difference over the whole day (P = 0.55). CONCLUSIONS: Under these study conditions a 1050 kJ oral supplement, irrespective of macronutrient composition, does not cause voluntary short-term energy intake compensation in undernourished elderly people.     

Ethnic differences in dietary intakes, physical activity, and energy expenditure in middle-aged, premenopausal women: the Healthy Transitions Study.

BACKGROUND: Menopause is a time of increased risk of obesity in women. The effect of menopause in African American women, in whom obesity is already highly prevalent, is unknown. OBJECTIVE: We compared dietary intakes and energy expenditure (EE) between middle-aged, premenopausal African American and white women participating in a longitudinal study of the menopausal transition. DESIGN: Dietary intakes by food record, EE by triaxial accelerometer, physical activity by self-report, and body composition by dual-energy X-ray absorptiometry were compared in 97 white and 52 African American women. Twenty-four-hour and sleeping EE were measured by whole-room indirect calorimetry in 56 women. RESULTS: Sleeping EE (adjusted for lean and fat mass) was lower in African American than in white women (5749 +/- 155 compared with 6176 +/- 75 kJ/d; P = 0.02); however, there was no significant difference in 24-h EE between groups. Reported leisure activity over the course of a week was less in African American than in white women (556 +/- 155 compared with 1079 +/- 100 kJ/d; P = 0.02), as were the daily hours spent standing and climbing stairs. Dietary intakes of protein, fiber, calcium, magnesium, and several fatty acids were significantly less in African Americans, whereas there were no observed ethnic differences in intakes of fat or carbohydrate. Body fat within the whole group was positively correlated with total, saturated, and monounsaturated fat intakes and inversely associated with fiber and calcium intakes. Fiber was the strongest single predictor of fatness. CONCLUSION: Ethnic differences in EE and the intake of certain nutrients may influence the effect of menopausal transition on obesity in African American women.     

Energy metabolism after 2 y of energy restriction: the biosphere 2 experiment

BACKGROUND: An adaptive decrease in energy expenditure (EE) in response to 6 mo of severely restricted energy intake was shown in a classic semistarvation study-the Minnesota experiment. OBJECTIVE: Our objective was to examine whether such adaptation also occurs in response to less severe but sustained energy restriction. DESIGN: Body composition, 1-wk total EE (TEE), 24-h sedentary EE, and spontaneous physical activity were measured in 8 healthy subjects (4 men and 4 women) at the end of a 2-y confinement inside Biosphere 2. Unexpectedly, the food supply was markedly restricted during most of the confinement and all subjects experienced a marked, sustained weight loss (9.1 +/- 6.6 kg; P: < 0.001) from the low-energy (7000-11000 kJ/d), low-fat (9% of energy), but nutrient-dense, diet they consumed. RESULTS: The TEE inside Biosphere 2, assessed 3 wk before exit, averaged 10700 +/- 560 kJ/d (n = 8). Within 1 wk after exit, the adjusted 24-h EE and spontaneous physical activity were lower in the biospherians (n = 5) than in 152 control subjects (6% and 45%, respectively; both P: < 0.01). Six months after exit and return to an ad libitum diet, body weight had increased to preentry levels; however, adjusted 24-h EE and spontaneous physical activity were still significantly lower than in control subjects. CONCLUSIONS: In lean humans, an adaptive decrease in EE appears to occur not only in states of life-threatening undernutrition, but also in response to less severe energy restriction sustained over several years.     

Postprandial ghrelin, cholecystokinin, peptide YY, and appetite before and after weight loss in overweight women with and without polycystic ovary syndrome

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common condition associated with obesity and with reproductive and metabolic dysfunction. Abnormalities in appetite regulation in PCOS patients may contribute to difficulties in weight management. OBJECTIVE: We aimed to examine appetite, appetite hormones, and ad libitum food consumption before and after weight loss in overweight women with and without PCOS. DESIGN: Overweight age- and weight-matched women with (n = 14) and without (n = 14) PCOS undertook an 8-wk energy-restricted diet (5185.3 +/- 141.6 kJ/d). At baseline and study end, subjects consumed a test meal (936 kJ; 25% of energy from protein, 9% from fat, and 67% from carbohydrate). Subjective appetite and circulating glucose, insulin, ghrelin, cholecystokinin, and peptide YY were assessed at 0, 15, 30, 45, 60, 90, 120, and 180 min. A mixed buffet lunch was then offered to assess ad libitum food intake. RESULTS: Weight loss (4.2 +/- 3.9 kg) did not differ significantly between the 2 groups. Women with PCOS had significantly (P = 0.023) lower ghrelin concentrations before and after weight loss than did women without PCOS. The degree of postprandial ghrelin suppression was lower at weeks 0 (P = 0.048) and 8 (P = 0.069) in women with PCOS than in women without PCOS. There were no significant differences between the 2 groups in appetite responses, buffet consumption, or fasting or postprandial peptide YY and cholecystokinin before or after weight loss. CONCLUSIONS: PCOS was associated with lower fasting ghrelin and a smaller postprandial ghrelin suppression both before and after weight loss but was not associated with other postprandial gut peptides, subjective satiety, or food intake. It is not clear whether appetite regulation is impaired in PCOS.     

Effect of hydroxycitrate on respiratory quotient, energy expenditure, and glucose tolerance in male rats after a period of restrictive feeding

OBJECTIVE: Recently we demonstrated that hydroxycitrate (HCA) suppresses food intake and body weight regain in male rats after substantial body weight loss. However, it is not known whether HCA also affects the respiration quotient (RQ), energy expenditure (EE), and glucose tolerance in this animal model. METHODS: Twenty-four male rats (initial body weight, 378 +/- 3 g) were fed restrictively (10 g/d) for 10 d and then given ad libitum access to a high-glucose diet supplemented with 3% HCA for 6 d. Controls received the same diet without the supplement. RQ and EE were measured during ad libitum days 1, 2, and 6. An oral glucose tolerance test was performed on ad libitum day 4 or 5. RESULTS: HCA decreased RQ and EE during ad libitum days 1 and 2. In all probability, these findings reflect a decrease in de novo lipogenesis. On ad libitum day 6, RQ and EE did not differ between treatment groups. HCA suppressed food intake during the first 3 d ad libitum, but overall body weight regain was not decreased in the HCA group. The oral glucose tolerance test showed that HCA significantly decreased the increase in plasma glucose from baseline (Deltaglucose) and tended to decrease the area under the curve for glucose. Deltainsulin and area under the curve for insulin did not differ between groups. CONCLUSIONS: These results indicate that, in this animal model, HCA suppresses de novo lipogenesis. Moreover, HCA may improve glucose tolerance.     

Dietary fat and appetite: similarities and differences in the satiating effect of meals supplemented with either fat or carbohydrate*†

In experiment 1, normal weight male subjects were provided with three types of breakfast consumed in the Human Appetite Research Unit on separate experimental days 1 week apart. The intensity of hunger, fullness and other subjective feelings were tracked by means of visual analogue rating scales at intervals during the day. Energy and nutrient intakes were measured directly from ad libitum test meals consumed at lunch and dinner. During the rest of the day and until after breakfast the following day, food intake was measured indirectly through weighted food records. The test breakfasts comprised a basic meal 184 1 kJ (440 kcal) and the same meal supplemented with similar amounts of either fat (1515 kJ, 362 kcal) or carbohydrate (1527 kJ, 365 kcal). No differences were detected between the effects of the basic breakfast compared with the fat-supplemented breakfast. The carbohydrate supplement suppressed hunger ratings during a limited period after consumption (the post-ingestive window coinciding with the expected metabolism of carbohydrate. In experiment 2, a direct test of consumption during this post-ingestive window confirmed that the carbohydrate supplemented breakfast suppressed intake but the fat supplement did not. These results demonstrate that carbohydrate and fat can produce quiet different effects on satiety. Under these experimental conditions the supplement of fat produced no detectable effect on the expression of appetite and illustrates how dietary fat could lead to passive over-consumption of energy. However this effect may be modified by the particular pattern of food consumption during the course of a day.     

A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations

BACKGROUND: Ad libitum, low-carbohydrate diets decrease caloric intake and cause weight loss. It is unclear whether these effects are due to the reduced carbohydrate content of such diets or to their associated increase in protein intake. OBJECTIVE: We tested the hypothesis that increasing the protein content while maintaining the carbohydrate content of the diet lowers body weight by decreasing appetite and spontaneous caloric intake. DESIGN: Appetite, caloric intake, body weight, and fat mass were measured in 19 subjects placed sequentially on the following diets: a weight-maintaining diet (15% protein, 35% fat, and 50% carbohydrate) for 2 wk, an isocaloric diet (30% protein, 20% fat, and 50% carbohydrate) for 2 wk, and an ad libitum diet (30% protein, 20% fat, and 50% carbohydrate) for 12 wk. Blood was sampled frequently at the end of each diet phase to measure the area under the plasma concentration versus time curve (AUC) for insulin, leptin, and ghrelin. RESULTS: Satiety was markedly increased with the isocaloric high-protein diet despite an unchanged leptin AUC. Mean (+/-SE) spontaneous energy intake decreased by 441 +/- 63 kcal/d, body weight decreased by 4.9 +/- 0.5 kg, and fat mass decreased by 3.7 +/- 0.4 kg with the ad libitum, high-protein diet, despite a significantly decreased leptin AUC and increased ghrelin AUC. CONCLUSIONS: An increase in dietary protein from 15% to 30% of energy at a constant carbohydrate intake produces a sustained decrease in ad libitum caloric intake that may be mediated by increased central nervous system leptin sensitivity and results in significant weight loss. This anorexic effect of protein may contribute to the weight loss produced by low-carbohydrate diets.     

Altering the temporal distribution of energy intake with isoenergetically dense foods given as snacks does not affect total daily energy intake in normal-weight men

The objectives of the present study were to examine the effects of (1) ingesting mandatory snacks v. no snacks and (2) the composition of isoenergetically-dense snacks high in protein, fat or carbohydrate, on food intake and energy intake (EI) in eight men with ad libitum access to a diet of fixed composition. Subjects were each studied four times in a 9 d protocol per treatment. On days 1-2, subjects were given a medium-fat maintenance diet estimated at 1.6 x resting metabolic rate (RMR). On days 3-9, subjects consumed three mandatory isoenergetic, isoenergetically dense (380 kJ/100 g) snacks at fixed time intervals (11.30, 15.30 and 19.30 hours). Total snack intake comprised 30% of the subjects' estimated daily energy requirements. The treatments were high protein (HP), high carbohydrate (HC), high fat (HF) and no snack (NS). The order was randomized across subjects in a counterbalanced, Latin-square design. During the remainder of the day, subjects had ad libitum (meal size and frequency) access to a covertly manipulated medium-fat diet of fixed composition (fat:carbohydrate:protein, 40:47:13 by energy), energy density 550 kJ/100 g. All foods eaten were investigator-weighed before ingestion and left-overs were weighed after ingestion. Subjective hunger and satiety feelings were tracked hourly during waking hours using visual analogue scales. Ad libitum EI amounted to 13.9 MJ/d on the NS treatment compared with 11.7, 11.7 and 12.2 MJ/d on the HP, HC and HF diets respectively (F(3,21) 5.35; P = 0.007, SED 0.66). Total EI values were not significantly different at 14.6, 14.5, 15.0 and 14.2 MJ/d respectively. Snack composition did not differentially affect total daily food intake or EI. Average daily hunger was unaffected by the composition of the snacks. Only at 12.00 hours did subjects feel significantly more hungry during the NS condition, relative to the other dietary treatments (F(3,18) 4.42; P = 0.017). Body weight was unaffected by dietary treatment. In conclusion, snacking per se led to compensatory adjustments in feeding behaviour in lean men. Snack composition (with energy density controlled) did not affect the amount eaten of a diet of fixed composition. Results may differ in real life where subjects can alter both composition and amount of food they eat and energy density is not controlled.     

Lipase inhibition attenuates the acute inhibitory effects of oral fat on food intake in healthy subjects

The lipase inhibitor, orlistat, is used in the treatment of obesity and reduces fat absorption by about 30%. However, the mean weight loss induced by orlistat is less than expected for the degree of fat malabsorption. It was hypothesised that lipase inhibition with orlistat attenuates the suppressive effects of oral fat on subsequent energy intake in normal-weight subjects. Fourteen healthy, lean subjects (nine males, five females; aged 25 +/- 1.3 years) were studied twice, in a double-blind fashion. The subjects received a high-fat yoghurt 'preload' (males 400 g (2562 kJ); females 300 g (1923 kJ)), containing orlistat (120 mg) on one study day (and no orlistat on the other 'control' day), 30 min before ad libitum access to food and drinks; energy intake was assessed during the following 8 h. Blood samples were taken at regular intervals for the measurement of plasma cholecystokinin (CCK). Each subject performed a 3 d faecal fat collection following each study. Energy intake during the day was greater following orlistat (10,220 (SEM 928) kJ) v. control (9405 (SEM 824) kJ) (P=0.02). On both days plasma CCK increased (P<0.05) after the preload. Plasma CCK 20 min following ingestion of the preload was less after orlistat (4.1 (SEM 0.9) pmol/l) v. control (5.3 (SEM 0.9) pmol/l (P=0.028); however there was no difference in the area under the curve 0-510 min between the two study days. Fat excretion was greater following orlistat (1017 (SEM 168) kJ) v. control (484 (SEM 90) kJ) (P=0.004). In conclusion, in healthy, lean subjects the acute inhibitory effect of fat on subsequent energy intake is attenuated by orlistat and the increase in energy intake approximates the energy lost due to fat malabsorption.     

Appetite dysfunction in obese males: evidence for role of hyperinsulinaemia in passive overconsumption with a high fat diet

OBJECTIVE: To test the hypothesis that caloric and fat intake in a pre-load meal have no subsequent effects upon blood glucose and insulin concentrations, perceived hunger, subsequent food intake and appetite control in lean and obese men. DESIGN: Lean and obese men reported to the laboratory in the morning in a fasted state where they were subject to an eating test based on the pre-load-test meal paradigm, using a double-blind protocol. The breakfast pre-load was either a reduced caloric low-fat (LF) meal or an overfeeding high-fat (HF) meal. LF was 20% of each individual's average daily energy requirement (ADER) and comprised 60% carbohydrate, 27% protein, and 13% fat, whilst HF was adjusted to yield 55% of the ADER, and comprised 45% carbohydrate, 22% protein and 43% fat. The pre-loads on both trials were administered as one single mean, and were given in a random order. After 5(1/2) h, an ad libitum test-lunch was given to determine how much energy was consumed. Between the two meals, blood samples were collected and subjective hunger ratings were assessed hourly. These variables were measured at 30-min intervals for 75 min after the ad libitum meal. STUDY PARTICIPANTS: Twelve healthy men, six of whom were lean (BMI 22. 50+/-1.08 kg.m2) and six of whom were obese (BMI 39.05+/-11.63 kg. m2) were recruited. RESULTS: When given 55% of their ADER in a HF pre-load meal, the obese group consumed more energy (5426+/-1126 kJ; F1,20=11.45, P<0.01), than the lean group did (3473+/-1114 kJ), accounting for 45% of the ADER in that meal setting. However, no differences between lean and obese intake were noted at the test meal following a LF pre-load. The lean group exhibited a significant inverse correlation (r=0.628, P<0.05) between serum insulin concentration before eating the test meal and the amount of energy consumed at the test meal, while such a relationship was absent in the obese group. CONCLUSION: The obese males were unable to compensate for the caloric overloading when fed a HF (55% ADER) pre-load at a subsequent test meal, whereas a calorically reduced pre-load (20% ADER) produced similar intakes to the lean control group. The inverse relationship noted in the lean group between insulin levels before the test meal and the energy intake at that test meal suggests that insulin may play a role in the regulation of appetite - satiety mechanism in lean males. The absence of such a relationship in the obese may suggest the site for possible appetite dysfunction contributing to obesity. These results further suggest that when obese individuals consume a high-fat meal they are prone to passive overconsumption, whereas lean study participants appear to be more resistant to such a phenomenon.     

Accuracy of dietary recall using the USDA five-step multiple-pass method in men: an observational validation study

OBJECTIVE: This observational validation study was conducted under controlled conditions to test the accuracy of dietary recall in normal weight, overweight, and obese men using the USDA five-step multiple-pass method for dietary recall. DESIGN: Cross-sectional analysis of actual and recalled intake of food during 1 day. SUBJECTS/SETTING: Forty-two men ranging in age from 21 to 65 years and in body mass index from 21 to 39 kg/m(2) who lived in the metropolitan Washington DC area were studied. INTERVENTION: The subjects selected and consumed all meals and snacks, for 1 day, from a wide variety of foods provided at a human study facility. MAIN OUTCOME MEASURES: Actual and recalled energy, protein, carbohydrate, and fat intakes were determined by direct observation and by a 24-hour dietary recall, respectively. Dietary recall was determined via telephone administration of the USDA five-step multiple-pass method the following day. STATISTICAL ANALYSES PERFORMED: Analysis of variance and covariance tested the overall accuracy of recall and the effect of body mass index on dietary recall. Bland-Altman plots were used to assess bias in recall of food intake. RESULTS: In this population of men, there were no significant differences between actual and recalled intakes of energy (3,294+/-111 and 3,541+/-124 kcal/day), protein (117+/-5 and 126+/-5 g/day), carbohydrate (414+/-16 and 449+/-16 g/day), or fat (136+/-7 and 146+/-8 g/day), respectively. Accuracy of recall was not related to body mass index in that the obese men recalled food intake as accurately as the nonobese men. The energy intake of these men was significantly correlated (r=0.57, P<.05) with their estimated energy requirements. Significant interindividual variation in accuracy of recall was found. CONCLUSIONS: Under controlled conditions, the USDA five-step multiple-pass method can accurately assess intakes of energy, protein, carbohydrate, and fat in a population of men regardless of their body mass index. Researchers and clinical dietitians need to continue to examine factors that influence underreporting and overreporting of food intake by the multiple-pass 24-hour recall method.     

The relationship between daytime and nighttime food intake in an obese night-eater

Some obese individuals consume food during awakenings from nighttime sleep. Three studies were conducted on a 28-year-old morbidly obese male with chronic sleeping complaints and insignificant weight loss, despite self-reported daily caloric restriction: I. For 3 mo, the subject recorded food intake for 24-h periods. Mean daytime intake was 1286 kcal +/- 386 (SD), and mean nighttime intake was 1036 kcal +/- 487 (SD). Caloric values of daytime and nighttime intake were negatively correlated, r = -0.22, df= 82, p < .05. II. Seven consecutive 24-h food intake recordings were obtained with an automated formula dispenser when the subject was an inpatient on a metabolic ward and received ad libitum formula as his sole food source. Mean daytime intake was 1245 +/- 662 (SD), and mean nighttime intake was 231 +/- 236 (SD). There was a non-significant negative correlation between daytime and nighttime intake, r = -0.32, df = 5, NS. III. The subject underwent polysomnographic studies on 2 non-consecutive nights, following the administration of either a low (600 kcal) or high (1800 kcal) daytime caloric condition. The subject, upon awakening from nighttime sleep, could eat from a platter of sandwich quarters placed at his bedside. The addition of 1200 kcal to daytime intake decreased nighttime intake by 654 kcal, or by 55% of the additional calories delivered during the day. The three studies (I, II, and III) show that daytime food intake can be negatively correlated with nighttime intake, and that daytime intake can influence nighttime intake in a documented obese night-eater.     

An ad libitum, very low-fat diet results in weight loss and changes in nutrient intakes in postmenopausal women

OBJECTIVES: To determine whether a very low-fat diet (<15% of energy intake) consumed ad libitum during an 8-month period can achieve weight loss of 5% to 10% of initial body weight while still providing adequate intakes of other essential nutrients. DESIGN: Longitudinal, 8-month, ad libitum, free living, very low-fat diet trial. SUBJECTS: Fifty-four of the sixty-four healthy postmenopausal women recruited completed the entire study (age 59+/-8 years, BMI=29.6+/-6.3). Twenty-four of these women used hormone replacement therapy, thirty women did not. INTERVENTION: Weekly sessions aimed at teaching and reinforcing a very low-fat intake diet for eight months. MAIN: outcome measures Body weight, percent body fat, waist-to-hip ratio, resting energy expenditure, respiratory quotient, and nutrient intakes derived from 7-day food records at the beginning and at 2, 4, 6, and 8 months of the study.Statistical analysis performed Repeated measures analysis of variance and Tukey post hoc analysis were used to analyze significant differences in mean data (P<.05). RESULTS: Fat intake decreased from 33.2+/-7.5% to 11+/-4% over the 8-month intervention period (P<.00001). Weight loss was 6.0 kg+/- 4.2 kg (P<.000038), an 8% weight change, and decrease in percent body fat of 2.7%+/-0.2% (P< or =.000046). Weight correlated better with the self-reported fat intake (r=0.321, P<.01) than the energy intake (r=0.263, P<.05) at baseline. Fiber intake increased from 16 g+/-0.6 g to 23 g+/-0.2 g (P<.0005). All micronutrient intakes remained at or above preintervention ranges, except for a decrease in vitamin E intake from 8.1 mg+/-4.0 mg to 3.7 mg+/-1.1 mg (P<.0005) on the very low-fat diet and linoleic acid from 6.3%+/-1.5% to 2.5%+/-0.7% (P<.000001) with no significant reduction in linolenic acid. Hormone replacement was not associated with the amount of weight loss. APPLICATIONS: This study demonstrates that adherence to a very low-fat diet consumed ad libitum causes weight loss in the 5% to 10% range and a reduction of body fat. These reductions, along with the observed decreases in fat intake, are associated with improved health outcomes. Because of the decreased vitamin E and n-3 fatty acid intake, emphasis on foods high in these nutrients may need to be encouraged for those consuming a very low-fat diet.     

Dietary composition and physiologic adaptations to energy restriction

BACKGROUND: The concept of a body weight set point, determined predominantly by genetic mechanisms, has been proposed to explain the poor long-term results of conventional energy-restricted diets in the treatment of obesity. OBJECTIVE: The objective of this study was to examine whether dietary composition affects hormonal and metabolic adaptations to energy restriction. DESIGN: A randomized, crossover design was used to compare the effects of a high-glycemic-index (high-GI) and a low-glycemic-index (low-GI) energy-restricted diet. The macronutrient composition of the high-GI diet was (as percent of energy) 67% carbohydrate, 15% protein, and 18% fat and that of the low-GI diet was 43% carbohydrate, 27% protein, and 30% fat; the diets had similar total energy, energy density, and fiber contents. The subjects, 10 moderately overweight young men, were studied for 9 d on 2 separate occasions. On days -1 to 0, they consumed self-selected foods ad libitum. On days 1-6, they received an energy-restricted high- or low-GI diet. On days 7-8, the high- or low-GI diets were consumed ad libitum. RESULTS: Serum leptin decreased to a lesser extent from day 0 to day 6 with the high-GI diet than with the low-GI diet. Resting energy expenditure declined by 10.5% during the high-GI diet but by only 4.6% during the low-GI diet (7.38 +/- 0.39 and 7.78 +/- 0.36 MJ/d, respectively, on days 5-6; P = 0.04). Nitrogen balance tended to be more negative, and energy intake from snacks on days 7-8 was greater, with the high-GI than the low-GI diet. CONCLUSION: Diets with identical energy contents can have different effects on leptin concentrations, energy expenditure, voluntary food intake, and nitrogen balance, suggesting that the physiologic adaptations to energy restriction can be modified by dietary composition.     

The 24-h carbohydrate oxidation rate in a human respiratory chamber predicts ad libitum food intake

BACKGROUND: The 24-h respiratory quotient (24-h RQ) and 24-h carbohydrate balance (24-h CHO-Bal) are predictors of weight change. Whether these relations are mediated by the effects of substrate oxidation and balance on food intake is not known. OBJECTIVE: We tested whether substrate oxidation and balance predict future ad libitum food intake. DESIGN: Substrate oxidation and balance were measured in a respiratory chamber in 112 normoglycemic subjects (83 Pima Indians and 29 whites; 67 men and 45 women) in energy balance for 3 d before tests were performed. The subjects then self-selected their food ad libitum for the following 3 d. RESULTS: The 24-h RQ, 24-h carbohydrate oxidation (24-h CHO-Ox), and 24-h CHO-Bal in the respiratory chamber predicted subsequent ad libitum food intake over 3 d (as a percentage of weight maintenance energy needs; %EN-WM). The 24-h CHO-Ox explained 15% of the variance in %EN-WM. The weight change over the 3-d ad libitum period was associated positively with 24-h CHO-Ox and negatively with 24-h CHO-Bal in the chamber; these associations were no longer significant after adjustment for %EN-WM. CONCLUSION: Carbohydrate oxidation and balance predict subsequent ad libitum food intake and can influence short-term weight changes, which indicates that carbohydrate balance is a contributing metabolic factor affecting food intake.