The effect of exercise on energy intake and body composition in overweight women

Twelve moderately overweight women with mild obesity were studied to determine the effect of exercise on nutrient intake and body composition. The women, 16 to 42 percent above desired body weight (BW) and 30 to 41 percent body fat, rotated through three 18-day treatment periods: no exercise (NO-EX), moderate duration exercise (M-EX), and long duration exercise (L-EX). Daily exercise was prescribed to increase energy expenditure by 12.5 (M-EX) or 25 percent (L-EX) of energy intake required for BW maintenance during baseline. Diets were self-selected from a variety of conventional foods, and intake was monitored. Exercise did not affect quantity of energy intake or macronutrient composition of diets during the treatment periods. Energy and carbohydrate intakes tended to be higher in response to M-EX and L-EX compared to NO-EX during the last 5-day interval of the treatment periods, but these trends were not statistically significant. Exercise did affect BW and fat-free mass (FFM); mean FFM values were 49.3, 49.7 and 50.8 kg at the end of NO-EX, M-EX and L-EX, respectively (P = 0.017). Body fat mass (FM) was not consistently affected by exercise. It appears that exercise affects FFM but has no consistent effect on nutrient intake in mildly obese women who are choosing food intake from a variety of foods.     

Leptin, thyrotropin, and thyroid hormones in obese/overweight women before and after two levels of energy deficit

The aim of our study was to compare serum concentration of leptin and pituitary-thyroid axis hormones in obese/overweight women before and after two levels of energy deficit with those parameters in lean women on adequate energy intake. Additionally, we attempted to elucidate if the effect of weight reduction could be related to anthropometric and hormonal parameters before treatment. Anthropometric and hormonal parameters—serum leptin, TSH, T4, fT4, T3 and leptin to fat mass (Lep/fm), T3/T4, fT4/T4, T4/TSH, fT4/TSH—were compared in two groups of women (n=18 each)—lean women (C: BMI 22.0±1.2) and overweight/obese (Ov/Ob: BMI 29.9±3.3). Ov/Ob women were subjected to weight-reducing treatment consisting of energy intake equal to 80% of calculated total energy expenditure for the first 4 wk and to 50% for subsequent 4 wk. All baseline hormone concentrations, Lep/fm, and fT4/T4 were higher in overweight/obese group. After 20% energy deficit decrease in BMI, percent body fat (fm%), leptin, T3, and TSH serum concentrations as well as in Lep/fm and T3/T4 was observed; T4/TSH increased, fT4, fT4/T4 and fT4/TSH did not change significantly. Increase in energy deficit from 20% to 50% resulted in normalization of Lep/fm, on the other hand, it provoked greater decline in thyroid hormone plasma concentration, which could hinder further mass reduction. Leptin and TSH levels were positively correlated after 50% energy deficit treatment. Changes in fm% were directly related to baseline T4/TSH, fT4/TSH, and log TSH. In conclusion, TSH serum concentration and its ratio to T4 and fT4 before weight reduction could be a good predictor of successful weight loss.     

Energetic and metabolic studies of intragastric infusion of calories before and after exercise training

The technique of intragastric infusion of calories was used to examine the energetics and metabolic response to fasting, feeding and overfeeding states in adult, sedentary subjects. All subjects were studied before and after participating in a 12-week aerobic exercise training program that increased maximum aerobic capacity by an average of 15.6 percent. Body weight did not change during the exercise program, but there was a slight and statistically significant increase in fat-free mass and a significant decrease in fat mass. The exercise program did not affect food intake (as determined from food records). When subjects were studied before exercise training, there was no increase in energy expenditure above fasting levels during continuous infusion of calories at a rate near the subject's maintenance energy requirements. When infusion rate was increased to twice maintenance, energy expenditure increased significantly and produced a measurable thermic effect of food. The changes in glucose, insulin and free fatty acids did not parallel the changes in energy expenditure, but changes in lactate levels did. Moreover, there were some gender differences in the pattern of substrate and hormone changes with changes in feeding state. Exercise training did not alter either energy expenditure or the pattern of changes in substrates and hormones with changes in feeding state. In summary, the exercise program led to changes in body composition without measurable changes in either food intake (assessed from diet records) or energy expenditure (assessed during fasting and continuous infusion of calories). The change in body composition must have been due to either (1) the energy cost of the exercise itself, or (2) changes in the substrates used for oxidation, either during or following exercise bouts. We conclude that exercise, unlike food restriction, can lead to changes in body composition without altering body weight or metabolic rate, and can contribute to the acquisition and maintenance of a desirable body weight and composition.     

The effect of weight loss by dieting or exercise on resting metabolic rate in overweight men

While resting metabolic rate (RMR) is known to decline during periods of energy restriction, the effect of exercise training during weight loss on RMR is less clear. We studied separately the effect of energy restriction and exercise training on weight loss and RMR in a one-year randomized, controlled trial. One hundred twenty-one overweight, sedentary men (age 30-59) who were randomly assigned to a control (C), energy restriction only (D), or exercise only (E) group were examined at baseline and after one year for changes in RMR as measured by standard indirect calorimetry. Relative to controls, E increased fitness and jogged an average of 9.97 +/- 5.6 miles/week and did not change energy intake while D significantly reduced energy consumption. Both groups achieved significant weight loss and fat mass loss when compared to the controls at the end of one year. After one year, the D group showed a small yet significant decline in RMR (kcal/h and kcal/FFM/h) when compared to controls and exercisers, while the E group showed no significant changes. Therefore, in moderately overweight men, a one-year program of weight loss by energy restriction produced a significant decline in RMR while weight loss by exercise did not change RMR.     

Energy expenditure and physical performance in overweight women: response to training with and without caloric restriction

The metabolic effects of exercise training and the influence of a moderate calorie restriction on the training response were examined in overweight women. Ten healthy women, 119% to 141% of desirable weight, completed the 14-week study. After a 2-week stabilization period, in which diets were designed to maintain body weight (BW), five women were assigned to a 12-week experimental program of diet and exercise (D + EX) that included a 50% reduction in energy intake and a program of moderate intensity aerobic exercise 6 days per week. The other five women were assigned to the same daily exercise (EX) and continued to consume the stabilization diet. Periodic measurements of resting metabolic rate (RMR), thermic effect of food (TEF), energy cost of exercise, and predicted maximal aerobic capacity (VO2 max) were obtained, and the respiratory quotient (RQ) was determined during rest and exercise. Body composition was monitored weekly. Tests of strength and anaerobic capacity were conducted. D + EX lost an average of approximately 1.1 kg/wk, which was 67% fat, 33% lean. EX lost approximately 0.5 kg/wk, which was 86% fat, 14% lean. In both groups, the exercise program resulted in an 11% to 13% improvement in VO2 max and an 8% to 16% decrease in energy expenditure at submaximal workloads. The caloric restriction significantly increased fat utilization during exercise. The RMR declined 9% in D + EX, from 1,550 to 1,411 kcal/d, whereas it was maintained in EX, 1,608 to 1,626 kcal/d. The decrease in RMR observed in D + EX was consistent with the loss of fat-free mass (FFM).(ABSTRACT TRUNCATED AT 250 WORDS)     

The dynamics of weight loss after gastric partition for gross obesity

Energy intake and expenditure have been assessed in patients before gastric partition for gross obesity, 3 months after operation when they were still losing weight and at 12 months when weight loss was complete and stable. Food intake was drastically reduced after surgery and the energy deficit so produced was sufficient to account completely for the weight loss, even when allowance was made for an adaptive reduction in energy expenditure. In a majority of patients, the eventual reduction in expenditure parallels the regression of metabolic rate against body mass index for a population of stable obese patients. However, the reduction in resting metabolic rate was maximal soon after the operation, when weight loss was far from complete. Weight loss stabilized at about 6 months, not due to a further reduction in energy expenditure but because energy intake recovered until the patient was again in energy balance.     

High protein intake sustains weight maintenance after body weight loss in humans

BACKGROUND: A relatively high percentage of energy intake as protein has been shown to increase satiety and decrease energy efficiency during overfeeding. AIM: To investigate whether addition of protein may improve weight maintenance by preventing or limiting weight regain after weight loss of 5-10% in moderately obese subjects. DESIGN OF THE STUDY: In a randomized parallel design, 148 male and female subjects (age 44.2 +/- 10.1 y; body mass index (BMI) 29.5 +/- 2.5 kg/m2; body fat 37.2 +/- 5.0%) followed a very low-energy diet (2.1 MJ/day) during 4 weeks. For subsequent 3 months weight-maintenance assessment, they were stratified according to age, BMI, body weight, restrained eating, and resting energy expenditure (REE), and randomized over two groups. Both groups visited the University with the same frequency, receiving the same counseling on demand by the dietitian. One group (n=73) received 48.2 g/day additional protein to their diet. Measurements at baseline, after weight loss, and after 3 months weight maintenance were body weight, body composition, metabolic measurements, appetite profile, eating attitude, and relevant blood parameters. RESULTS: Changes in body mass, waist circumference, REE, respiratory quotient (RQ), total energy expenditure (TEE), dietary restraint, fasting blood-glucose, insulin, triacylglycerol, leptin, beta-hydroxybutyrate, glycerol, and free fatty acids were significant during weight loss and did not differ between groups. During weight maintenance, the 'additional-protein group' showed in comparison to the nonadditional-protein group 18 vs 15 en% protein intake, a 50% lower body weight regain only consisting of fat-free mass, a 50% decreased energy efficiency, increased satiety while energy intake did not differ, and a lower increase in triacylglycerol and in leptin; REE, RQ, TEE, and increases in other blood parameters measured did not differ. CONCLUSION: A 20% higher protein intake, that is, 18% of energy vs 15% of energy during weight maintenance after weight loss, resulted in a 50% lower body weight regain, only consisting of fat-free mass, and related to increased satiety and decreased energy efficiency.     

The role of energy expenditure in the differential weight loss in obese women on low-fat and low-carbohydrate diets

We have recently reported that obese women randomized to a low-carbohydrate diet lost more than twice as much weight as those following a low-fat diet over 6 months. The difference in weight loss was not explained by differences in energy intake because women on the two diets reported similar daily energy consumption. We hypothesized that chronic ingestion of a low-carbohydrate diet increases energy expenditure relative to a low-fat diet and that this accounts for the differential weight loss. To study this question, 50 healthy, moderately obese (body mass index, 33.2 +/- 0.28 kg/m(2)) women were randomized to 4 months of an ad libitum low-carbohydrate diet or an energy-restricted, low-fat diet. Resting energy expenditure (REE) was measured by indirect calorimetry at baseline, 2 months, and 4 months. Physical activity was estimated by pedometers. The thermic effect of food (TEF) in response to low-fat and low-carbohydrate breakfasts was assessed over 5 h in a subset of subjects. Forty women completed the trial. The low-carbohydrate group lost more weight (9.79 +/- 0.71 vs. 6.14 +/- 0.91 kg; P < 0.05) and more body fat (6.20 +/- 0.67 vs. 3.23 +/- 0.67 kg; P < 0.05) than the low-fat group. There were no differences in energy intake between the diet groups as reported on 3-d food records at the conclusion of the study (1422 +/- 73 vs. 1530 +/- 102 kcal; 5954 +/- 306 vs. 6406 +/- 427 kJ). Mean REE in the two groups was comparable at baseline, decreased with weight loss, and did not differ at 2 or 4 months. The low-fat meal caused a greater 5-h increase in TEF than did the low-carbohydrate meal (53 +/- 9 vs. 31 +/- 5 kcal; 222 +/- 38 vs. 130 +/- 21 kJ; P = 0.017). Estimates of physical activity were stable in the dieters during the study and did not differ between groups. These results confirm that short-term weight loss is greater in obese women on a low-carbohydrate diet than in those on a low-fat diet even when reported food intake is similar. The differential weight loss is not explained by differences in REE, TEF, or physical activity and likely reflects underreporting of food consumption by the low-fat dieters.     

Body mass regulation at altitude

Altitude exposure decreases energy intake and thus induces an energy deficit resulting in the loss of body mass. The energy deficit is worsened when energy expenditure is increased by exercise because the increase is not matched by an increased energy intake. The indicated fuel for the optimal use of the rarefied oxygen at altitude is carbohydrate. For optimal taste and maximizing energy intake, fat is the best. Protein should rather be limited because of its high thermic effect. Intestinal malabsorption probably does not play a role in the energy deficit. Even though the sensation of exertion during climbing at high altitude is intense, the actual energy expenditure is not high.     

Calorimetric results in man: energy output in normal and overweight subjects.

In order to test the practicability of 24-hr investigations with the gradient-free Vienna Whole-Body Calorimeter, energy output was measured over 24-hr periods in 18 human subjects. Heat loss was partitioned into dry and evaporative components. Sixteen female subjects were divided into normal-weight (less than 100% according to the Broca index), overweight (100%--120%), and obese (over 120%) groups. A male with severe hypothyroidism, and a female with no signs of impairment of thyroid function who had weight problems that were suspected to be due to low energy expenditure, were studied separately. Subjects reported that the calorimeter chamber was sufficiently comfortable for at least a 24-hour investigation. Overweight and obese subjects showed both greater total heat output and greater inter-individual variability than the normal weight group. Normal and overweight subjects were on steady levels of food intake that were representative of usual intake. For normal subjects there was a relatively close correspondence between energy intake and output, but not for overweight subjects. Thyroid hormone therapy produced a large increase in energy output in the hypothyroid patient. Energy expenditure was found to be unusually low in the patient with weight problems and was increased by about 50% after thyroid hormone administration.     

Maintenance of resting energy expenditure after weight loss in premenopausal women: potential benefits of a high-protein, reduced-calorie diet

The number of contemporary diet plans promoting high protein intakes for weight management has increased dramatically. Complementing this dietary approach with increased physical activity has proven to be beneficial. Recent studies have suggested that protein intakes in excess of the current Recommended Dietary Allowance (0.8 g/kg) may be of metabolic benefit during weight loss. This investigation assessed changes in resting energy expenditure and substrate oxidation in overweight and obese premenopausal women in response to a weight loss intervention that combined a high-protein, reduced-calorie diet with increased physical activity. Thirty-nine overweight and obese premenopausal women (age, 30.9 +/- 1.5 years; body mass index, 30.2 +/- 0.5 kg/m2) participated in a 10-week weight loss program in which they ate a reduced-calorie diet for which protein provided 30% of total energy and approximated 1.4 g/kg. Subjects incrementally increased physical activity (ie, steps walking) throughout the diet intervention period. Resting energy expenditure, substrate oxidation, and body composition were assessed before (PRE) and after (POST) the 10-week weight loss program. Subjects experienced a 5% decrease in body weight, with significant decreases in both fat mass (PRE, 35.5 +/- 1.2 kg; POST, 32.4 +/- 1.1 kg; P < .0001) and fat-free mass (PRE, 44.6 +/- 0.7 kg; POST, 43.6 +/- 0.7 kg; P < .0001). Changes in body weight or body composition did not alter resting energy expenditure. Protein oxidation increased (PRE, 18% +/- 1%; POST, 20% +/- 1%; P < .05) and fat oxidation decreased (PRE, 37% +/- 3%; POST, 30% +/- 3%; P < .05) after the 10-week intervention. These findings illustrate that a weight loss intervention combining consumption of a high-protein, reduced-calorie diet with increased physical activity promotes weight loss without negatively impacting resting energy expenditure in this population of women.     

Effects of an ad libitum low-fat, high-carbohydrate diet on body weight, body composition, and fat distribution in older men and women: a randomized controlled trial

BACKGROUND: The efficacy of ad libitum low-fat diets in reducing body weight and fat in overweight and obese adults remains controversial. METHODS: We examined the effect of a 12-week low-fat, high-complex carbohydrate diet alone (HI-CHO) and in combination with aerobic exercise training (HI-CHO + EX) on body weight and composition in 34 individuals with impaired glucose tolerance (20 women and 14 men; mean +/- SEM age, 66 +/- 1 years). Participants were randomly assigned to a control diet (41% fat, 14% protein, 45% carbohydrates, and 7 g of fiber per 1000 kcal), a HI-CHO diet (18% fat, 19% protein, 63% carbohydrates, and 26 g of fiber per 1000 kcal), or a HI-CHO diet plus endurance exercise 4 d/wk, 45 min/d, at 80% peak oxygen consumption (HI-CHO + EX). Participants were provided 150% of estimated energy needs and were instructed to consume food ad libitum. Total food intake, body composition, resting metabolic rate, and substrate oxidation were measured. RESULTS: There was no significant difference in total food intake among the 3 groups and no change in energy intake over time. The HI-CHO + EX and HI-CHO groups lost more body weight (-4.8 +/- 0.9 kg [P=.003] and -3.2 +/- 1.2 kg [P=.02]) and a higher percentage of body fat (-3.5% +/- 0.7% [P=.01] and -2.2% +/- 1.2% [P=.049]) than controls (-0.1 +/- 0.6 kg and 0.2% +/- 0.6%). In addition, thigh fat area decreased in the HI-CHO (P=.003) and HI-CHO + EX (P<.001) groups compared with controls. High carbohydrate intake and weight loss did not result in a decreased resting metabolic rate or reduced fat oxidation. CONCLUSION: A high-carbohydrate diet consumed ad libitum, with no attempt at energy restriction or change in energy intake, results in losses of body weight and body fat in older men and women.     

Physiologic changes after diet combined with structured aerobic exercise or lifestyle activity

Moderate intensity physical activity achieved through changes in lifestyle may promote weight management. However, little is known about changes in physiologic and metabolic variables when patients lose weight using moderate intensity lifestyle activity instead of traditional structured vigorous aerobic exercise. To compare changes in resting metabolic energy expenditure (REE), fat mass (FM), and fat-free mass (FFM) associated with a 12-week weight loss program combined with either: (1) aerobic exercise (AER); or (2) lifestyle activity (LIFE), we randomized 39 overweight adults (mean body mass index [BMI] = 30.9 +/- 2.8 kg/m(2)) to either diet plus AER (N = 18) or diet plus LIFE (N = 21). Both groups consumed a self-selected diet of 1,200 to 1,800 kcal/d (5,021 to 7,531 kJ/d). The AER group performed vigorous aerobic exercise for up to 45 minutes 3 to 4 d/wk. The LIFE group accumulated 30 minutes of moderate intensity physical activity on most days of the week. Compliance with the respective protocols was monitored on a weekly basis. REE was measured before and after treatment via open-circuit spirometry. The AER group decreased body weight by 8.4% (P<.001)while the LIFE had a reduction of 6.7% (P <.001) after treatment. Over the course of the interventions, the AER and LIFE groups experienced 10.9% (P <.001) and 10.2% (P <.001) reductions in REE, respectively. Aerobic exercise did not prevent reductions in REE to a greater extent than did lifestyle activity in patients consuming a reduced calorie diet. Change in REE was not related to changes in FFM or FM for either group, and there were no differences between groups in reductions of REE, weight, FM, or FFM. A program of diet plus lifestyle physical activity may be a suitable alternative for dieting adults who have difficulty adhering to a program of vigorous activity.     

Oxyntomodulin increases energy expenditure in addition to decreasing energy intake in overweight and obese humans: a randomised controlled trial

BACKGROUND: Oxyntomodulin has recently been found to decrease body-weight in obese humans and may be a potential anti-obesity therapy. OBJECTIVE: To determine whether oxyntomodulin alters energy expenditure, in addition to reducing energy intake, in 'free-living' overweight and obese volunteers. DESIGN: Randomized double-blind controlled cross-over trial. SETTING: Community and hospital-based. PARTICIPANTS: Fifteen healthy overweight and obese men and women (age: 23-49 years, BMI: 25.1-39.0 kg/m(2)). All volunteers completed the study protocol. INTERVENTIONs: Four-day subcutaneous self-administration of pre-prandial oxyntomodulin, three times daily. Participants were advised to maintain their normal dietary and exercise regimen. MEASUREMENTS: (1) Energy expenditure, measured by indirect calorimetry and combined heart rate and movement monitoring; (2) energy intake, measured during a study meal. RESULTS: Oxyntomodulin administration reduced energy intake at the study meal by 128+/-29 kcal (P=0.0006) or 17.3+/-5.5% (P=0.0071), with no change in meal palatability. Oxyntomodulin did not alter resting energy expenditure; but increased activity-related energy expenditure by 143+/-109 kcal/day or 26.2+/-9.9% (P=0.0221); total energy expenditure by 9.4+/-4.8% (P=0.0454) and physical activity level by 9.5+/-4.6% (P=0.0495). A reduction in body weight of 0.5+/-0.2% was observed during the oxyntomodulin administration period (P=0.0232). CONCLUSIOn: Oxyntomodulin increases energy expenditure while reducing energy intake resulting in negative energy balance. This data supports the role of oxyntomodulin as a potential anti-obesity therapy.     

Energy content of weight loss: kinetic features during voluntary caloric restriction

The classic rule stating that restricting intake by 3500 kcal/wk will lead to a 1-lb/wk rate of weight loss has come under intense scrutiny. Generally not a component of most weight loss prediction models, the "early" rapid weight loss phase may represent a period during which the energy content of weight change (ΔEC/ΔW) is low and thus does not follow the classic "rule." The current study tested this hypothesis. Dynamic ΔEC/ΔW changes were examined in 23 Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Study overweight men and women evaluated by dual-energy x-ray absorptiometry during weight loss at treatment weeks 4 to 24. Changes from baseline in body energy content were estimated from fat and fat-free mass. Repeated-measures analysis of variance was used to determine if ΔEC/ΔW changed significantly over time. The evaluation was expanded with addition of the Kiel 13-week weight loss study of 75 obese men and women to test with adequate power if there are sex differences in ΔEC/ΔW. The analysis of variance CALERIE time effect was significant (P < .001), with post hoc tests indicating that ΔEC/ΔW (kilocalories per kilogram) increased significantly from week 4 (X ± SEM; 4, 858 ± 388) to 6 (6, 041 ± 376, P < .01) and changed insignificantly thereafter; ΔEC/ΔW was significantly larger for Kiel women (6, 804 ± 226) vs men (6, 119 ± 240, P < .05). Sex-specific dynamic relative changes in body composition and related ΔEC/ΔW occur with weight loss initiation that extend for 1 month or more. These observations provide new information for developing energy balance models and further define limitations of the 3500-kcal energy deficit → 1-lb weight loss rule.     

Effect of calorie restriction with or without exercise on body composition and fat distribution

CONTEXT: There is debate over the independent and combined effects of dieting and increased physical activity on improving metabolic risk factors (body composition and fat distribution). OBJECTIVE: The objective of the study was to conduct a randomized, controlled trial (CALERIE) to test the effect of a 25% energy deficit by diet alone or diet plus exercise for 6 months on body composition and fat distribution. DESIGN: This was a randomized, controlled trial. SETTING: The study was conducted at an institutional research center. PARTICIPANTS: Thirty-five of 36 overweight but otherwise healthy participants (16 males, 19 females) completed the study. INTERVENTION: Participants were randomized to either control (healthy weight maintenance diet, n = 11), caloric restriction (CR; 25% reduction in energy intake, n = 12), or caloric restriction plus exercise (CR+EX; 12.5% reduction in energy intake + 12.5% increase in exercise energy expenditure, n = 12) for 6 months. MAIN OUTCOME MEASURES: Changes in body composition by dual-energy x-ray absorptiometry and changes in abdominal fat distribution by multislice computed tomography were measured. Results: The calculated energy deficit across the intervention was not different between CR and CR+EX. Participants lost approximately 10% of body weight (CR: - 8.3 +/- 0.8, CR+EX: - 8.1 +/- 0.8 kg, P = 1.00), approximately 24% of fat mass (CR: - 5.8 +/- 0.6, CR+EX: - 6.4 +/- 0.6 kg, P = 0.99), and 27% of abdominal visceral fat (CR: 0.9 +/- 0.2, CR+EX: 0.8 +/- 0.2 kg, P = 1.00). Both whole-body and abdominal fat distribution were not altered by the intervention. CONCLUSION: Exercise plays an equivalent role to CR in terms of energy balance; however, it can also improve aerobic fitness, which has other important cardiovascular and metabolic implications.     

Dietary approaches to reducing body weight.

Diet is one of the cornerstones of a weight loss programme. Although there is little evidence that diet composition plays a clinically important role in the absorption or expenditure of energy, it does appear to play a role in food intake. Diets with a deficit of 500-1000 kcal per day will produce weight losses of between 300 and 1000 g per week, depending on the patient's weight. Formulae for estimating energy intake are provided. Starvation diets with an energy intake below 200 kcal per day are no longer used, but very low-energy diets with an energy intake of between 200 and 800 kcal per day have been used, although there is little to support the use of energy levels below 800 kcal per day. Ad libitum low-fat diets have been reported to produce weight losses that average 1.6 g per day for each 1% reduction in the level of fat. In a meta-analysis, overweight subjects lost 5-7 kg before reaching a new plateau. In normal weight subjects, the loss was only 0.5 kg. A low-fat diet may be of value in helping patients to maintain their weight loss. Higher-protein diets were more effective than low-protein diets in one clinical trial. The type of carbohydrate in the low-fat diet does not appear to influence weight loss. Alcohol, on the other hand, is poorly satiating and may replace fat in oxidative processes, thus enhancing the risk of obesity.