Manuela P. G. M. Lejeune

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, β-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.

Protein-induced satiety: Effects and mechanisms of different proteins

Relatively high protein diets, i.e. diets that maintain the absolute number of grams of protein ingested as compared to before dieting, are a popular strategy for weight loss and weight maintenance. Research into multiple mechanisms regulating body weight has focused on the effects of different quantities and types of dietary protein. Satiety and energy expenditure are important in protein-enhanced weight loss and weight maintenance. Protein-induced satiety has been shown acutely, with single meals, with contents of 25% to 81% of energy from protein in general or from specific proteins, while subsequent energy intake reduction was significant. Protein-induced satiety has been shown with high protein ad libitum diets, lasting from 1 to 6 days, up to 6 months. Also significantly greater weight loss has been observed in comparison with control. Mechanisms explaining protein-induced satiety are nutrient-specific, and consist mainly of synchronization with elevated amino acid concentrations. Different proteins cause different nutrient related responses of (an)orexigenic hormones. Protein-induced satiety coincides with a relatively high GLP-1 release, stimulated by the carbohydrate content of the diet, PYY release, while ghrelin does not seem to be especially affected, and little information is available on CCK. Protein-induced satiety is related to protein-induced energy expenditure. Finally, protein-induced satiety appears to be of vital importance for weight loss and weight maintenance. With respect to possible adverse events, chronic ingestion of large amounts of sulphur-containing amino acids may have an indirect effect on blood pressure by induction of renal subtle structural damage, ultimately leading to loss of nephron mass, and a secondary increase in blood pressure. The established synergy between obesity and low nephron number on induction of high blood pressure and further decline of renal function identifies subjects with obesity, metabolic syndrome and diabetes mellitus II as particularly susceptible groups.

Effects of green tea on weight maintenance after body-weight loss.

The present study was conducted to investigate whether green tea may improve weight maintenance by preventing or limiting weight regain after weight loss of 5 to 10 % in overweight and moderately obese subjects. The study had a randomised, parallel, placebo-controlled design. A total of 104 overweight and moderately obese male and female subjects (age 18-60 years; BMI 25-35 kg/m(2)) participated. The study consisted of a very-low-energy diet intervention (VLED; 2.1 MJ/d) of 4 weeks followed by a weight-maintenance period of 13 weeks in which the subjects received green tea or placebo. The green tea contained caffeine (104 mg/d) and catechins (573 mg/d, of which 323 mg was epigallocatechin gallate). Subjects lost 6.4 (sd 1.9) kg or 7.5 (sd 2.2) % of their original body weight during the VLED (P<0.001). Body-weight regain was not significantly different between the green tea and the placebo group (30.5 (sd 61.8) % and 19.7 (sd 56.9) %, respectively). In the green tea treatment, habitual high caffeine consumption was associated with a higher weight regain compared with habitual low caffeine consumption (39 (sd 17) and 16 (sd 11) %, respectively; P<0.05). We conclude that weight maintenance after 7.5 % body-weight loss was not affected by green tea treatment and that habitual caffeine consumption affected weight maintenance in the green tea treatment.

Additional protein intake limits weight regain after weight loss in humans

Since long-term weight maintenance (WM) is a major problem, interventions to improve WM are needed. The aim of the study was to investigate whether the addition of protein to the diet might limit weight regain after a weight loss of 5-10 % in overweight subjects. In a randomised parallel study design, 113 overweight subjects (BMI 29.3 (SD 2.5) kg/m2); age 45.1 (SD 10.4) years) followed a very-low-energy diet for 4 weeks, after which there was a 6-month period of WM. During WM, subjects were randomised into either a protein group or a control group. The protein group received 30 g/d protein in addition to their own usual diet. During the very-low-energy diet, no differences were observed between the groups. During WM, the protein group showed a higher protein intake (18 % v. 15 %; P<0.05), a lower weight regain (0.8 v. 3.0 kg; P<0.05), a decreased waist circumference (-1.2 (SD 0.7) v. 0.5 (SD 0.5 ) cm; P<0.05) and a smaller increase in respiratory quotient (0.03 (SD 0.01) v. 0.07 0.01; (SD/)P <0.05) compared with the control group. Weight regain in the protein group consisted of only fat-free mass, whereas the control group gained fat mass as well. Satiety in the fasted state before breakfast increased significantly more in the protein group than in the control group. After 6 months follow-up, body weight showed a significant group x time interaction. A protein intake of 18 % compared with 15 % resulted in improved WM in overweight subjects after a weight loss of 7.5 %. This improved WM implied several factors, i.e. improved body composition, fat distribution, substrate oxidation and satiety.

Sensory and gastrointestinal satiety effects of capsaicin on food intake

BACKGROUND:Decreased appetite and increased energy expenditure after oral consumption of red pepper has been shown.OBJECTIVE:The aim of the present study was to assess the relative oral and gastrointestinal contribution to capsaicin-induced satiety and its effects on food intake or macronutrient selection.METHODS:For 24 subjects (12 men and 12 women; age: 35±10 y; BMI: 25.0±2.4 kg/m2; range 20–30), 16 h food intake was assessed four times during 2 consecutive days by offering macronutrient-specific buffets and boxes with snacks, in our laboratory restaurant. At 30 min before each meal, 0.9 g red pepper (0.25% capsaicin; 80 000 Scoville Thermal Units) or a placebo was offered in either tomato juice or in two capsules that were swallowed with tomato juice. Hunger and satiety were recorded using Visual Analogue Scales.RESULTS:Average daily energy intake in the placebo condition was 11.5±1.0 MJ/d for the men and 9.4±0.8 MJ/d for the women. After capsaicin capsules, energy intake was 10.4±0.6 and 8.3±0.5 MJ/d (P<0.01); after capsaicin in tomato juice, it was 9.9±0.7 and 7.9±0.5 MJ/d, respectively (compared to placebo: P<0.001; compared to capsaicin in capsules: P<0.05). En % from carbohydrate/protein/fat (C/P/F): changed from 46±3/15±1/39±2 to 52±4/15±1/33±2 en% (P<0.01) in the men, and from 48±4/14±2/38±3 to 42±4/14±2/32±3 en% (P<0.01) in the women, in both capsaicin conditions. Satiety (area under the curve) increased from 689 to 757 mmh in the men and from 712 to 806 mmh in the women, both (P<0.01). Only in the oral exposure condition was the reduction in energy intake and the increase in satiety related to perceived spiciness.CONCLUSION:In the short term, both oral and gastrointestinal exposure to capsaicin increased satiety and reduced energy and fat intake; the stronger reduction with oral exposure suggests a sensory effect of capsaicin.

Effect of capsaicin on substrate oxidation and weight maintenance after modest body-weight loss in human subjects

The aim of the present study was to investigate whether capsaicin assists weight maintenance by limiting weight regain after weight loss of 5 to 10 %. In this randomized double-blind placebo-controlled study, ninety-one moderately overweight subjects were randomly assigned to an intensive group that underwent all the measurements, and an extensive group that underwent the same measurements except the metabolism measurements. After a 4-week very-low-energy diet (VLED) intervention, a 3-month weight-maintenance period followed. During weight maintenance, subjects were divided into a capsaicin (135 mg capsaicin/d) and a placebo group. Body mass was measured before and after the VLED and after 1, 2 and 3 months of weight maintenance. The mean body-mass loss during the VLED was 6.6 (SD 2.0) kg (7.8 (SD 1.8) % initial body mass), and was not different between the subsequent treatment and placebo group. During weight maintenance, mean % regain during treatment was not significantly different compared with placebo (33.3 (SD 35.7) v. 19.2 (SD 41.8) %, P=0.09). RQ was significantly less increased during weight maintenance in the treatment group compared with placebo (0.04 (SD 0.06) v. 0.07 (SD 0.05), P<0.05), indicating a relatively more sustained fat oxidation. Fat oxidation (g/h) after weight maintenance was higher in the capsaicin group compared with placebo (4.2 (SD 1.1) v. 3.5 (SD 0.9), P<0.05). These results indicate that capsaicin treatment caused sustained fat oxidation during weight maintenance compared with placebo. However, capsaicin treatment has no limiting effect on 3-month weight regain after modest weight loss.

The effect of conjugated linoleic acid supplementation after weight loss on body weight regain, body composition, and resting metabolic rate in overweight subjects

OBJECTIVE: To study the effects of 13 weeks conjugated linoleic acid (CLA) supplementation in overweight subjects after weight loss on weight regain, body composition, resting metabolic rate, substrate oxidation, and blood plasma parameters.DESIGN: This study had a double-blind, placebo-controlled randomized design. Subjects were first submitted to a very-low-calorie diet (VLCD 2.1 MJ/d) for 3 weeks after which they started with the 13-week intervention period. They either received 1.8 g CLA or placebo per day (low dosage, LD) or 3.6 g CLA or placebo per day (high dosage, HD).SUBJECTS: A total of 26 men and 28 women (age 37.8±7.7 y; body mass index (BMI) 27.8±1.5 kg/m2).MEASUREMENTS: Before VLCD (t=−3), after VLCD but before CLA or placebo intervention (t=0) and after 13-week CLA or placebo intervention (t=13), body weight, body composition (hydrodensitometry and deuterium dilution), resting metabolic rate, substrate oxidation, physical activity, and blood plasma parameters (glucose, insulin, triacylglycerol, free fatty acids, glycerol and β-hydroxy butyrate) were measured.RESULTS: The VLCD significantly lowered body weight (6.9±1.7%), %body fat, fat mass, fat-free mass, resting metabolic rate, respiratory quotient and plasma glucose, insulin, and triacylglycerol concentrations, while free fatty acids, glycerol and β-hydroxy butyrate concentrations were increased. Multiple regression analysis showed that at the end of the 13-week intervention, CLA did not affect %body weight regain (CLA LD 47.9±88.2%, CLA HD 27.4±29.8%, Placebo LD 32.0±42.8%, Placebo HD 22.5±37.9%). The regain of fat-free mass was increased by CLA (LD 6.2±3.9, HD 4.6±2.4%) compared to placebo (LD 2.8±3.2%, HD 3.4±3.6%), independent of %body weight regain and physical activity. As a consequence of an increased regain of fat-free mass by CLA, resting metabolic rate was increased by CLA (LD 12.0±11.4%, HD 13.7±14.4%) compared to placebo (LD 9.1±11.0%, HD 8.6±8.5%). Substrate oxidation and blood plasma parameters were not affected by CLA.CONCLUSION: In conclusion, the regain of fat-free mass was favorably, dose-independently affected by a 13-week consumption of 1.8 or 3.6 g CLA/day and consequently increased the resting metabolic rate. However, it did not result in improved body weight maintenance after weight loss.

Dietary protein, metabolism, and body-weight regulation: dose–response effects

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

Effect of conjugated linoleic acid supplementation after weight loss on appetite and food intake in overweight subjects

Objective: To study the effects of 13 weeks conjugated linoleic acid (CLA) supplementation in overweight subjects on body-weight maintenance, parameters of appetite and energy intake (EI) at breakfast after weight loss.Design: This study had a double-blind, placebo-controlled randomized design.Subjects: A total of 26 men and 28 women (age 37.8±7.7 y; body mass index 27.8±1.5 kg/m2).Interventions: Subjects were first submitted to a very-low-calorie diet (VLCD; 2.1 MJ/day) for 3 weeks after which they started with the 13-week intervention period. They either received 1.8 g CLA or placebo per day or 3.6 g CLA or placebo per day. Additionally, subjects of the high dosage intervention replaced their habitual lunch by one meal of a protein-rich, low-energy supplement. EI was measured at breakfast and appetite profile after an overnight fast.Results: The mean body weight loss was 6.9±1.7% of their original body weight. Multiple regression analysis showed that at the end of the 13-week intervention, CLA did not have an effect on body weight regain. Feelings of fullness and satiety were increased and feelings of hunger were decreased after 13 weeks intervention by CLA compared to placebo, independent of %body weight regain. However, EI measured at breakfast was not affected by CLA.Conclusions: Appetite (hunger, satiety and fullness) was favorably, dose-independently affected by a 13-week consumption of 1.8 or 3.6 g CLA/day. This did not result in a lower EI at breakfast or an improved body-weight maintenance after weight loss.

Protein intake and body-weight regulation

Body-weight management requires a multi-factorial approach. Recent findings suggest that an elevated protein intake seems to play such a key role in body-weight management, through (i) increased satiety related to increased diet-induced thermogenesis, (ii) its effect on thermogenesis, (iii) body composition, and (iv) decreased energy-efficiency. Supported by these mechanisms a relatively larger weight loss and stronger body-weight maintenance thereafter have been observed.