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Background: It has been suggested that perturbations in branched-chain amino acid (BCAA) catabolism are associated with insulin resistance and contribute to elevated systemic BCAAs. Evidence in rodents suggests dietary protein rich in BCAAs can increase BCAA catabolism, but there is limited evidence in humans., Objective: We hypothesize that a diet rich in BCAAs will increase BCAA catabolism, which will manifest in a reduction of fasting plasma BCAA concentrations., Methods: The metabolome of 27 obese women with metabolic syndrome before and after weight loss was investigated to identify changes in BCAA metabolism using GC-time-of-flight mass spectrometry. Subjects were enrolled in an 8-wk weight-loss study including either a 20-g/d whey (whey group, n = 16) or gelatin (gelatin group, n = 11) protein supplement. When matched for total protein by weight, whey protein has 3 times the amount of BCAAs compared with gelatin protein., Results: Postintervention plasma abundances of Ile (gelatin group: 637 ± 18, quantifier ion peak height ÷ 100; whey group: 744 ± 65), Leu (gelatin group: 1210 ± 33; whey group: 1380 ± 79), and Val (gelatin group: 2080 ± 59; whey group: 2510 ± 230) did not differ between treatment groups. BCAAs were significantly correlated with homeostasis model assessment of insulin resistance at baseline (r = 0.52, 0.43, and 0.49 for Leu, Ile, and Val, respectively; all, P < 0.05), but correlations were no longer significant at postintervention. Pro- and Cys-related pathways were found discriminant of whey protein vs. gelatin protein supplementation in multivariate statistical analyses., Conclusions: These findings suggest that BCAA metabolism is, at best, only modestly affected at a whey protein supplementation dose of 20 g/d. Furthermore, the loss of an association between postintervention BCAA and homeostasis model assessment suggests that factors associated with calorie restriction or protein intake affect how plasma BCAAs relate to insulin sensitivity. This trial was registered at clinicaltrials.gov as NCT00739479., (© 2015 American Society for Nutrition.)

Fat accumulation is associated with the release of many novel adipokines such as retinol-binding protein 4 and fatty acid-binding protein 4. These adipokines have been linked to insulin resistance, metabolic syndrome, type 2 diabetes and cardiovascular disease. Since weight loss is the first step for the treatment of metabolic syndrome, which increases the risks for both type 2 diabetes and cardiovascular disease, we have investigated the effects of weight loss on serum retinol-binding protein 4 and fatty acid-binding protein 4 in obese individuals with this syndrome. Twenty-nine obese female subjects with metabolic syndrome, aged 18-62 years completed a 2-month weight loss diet plan. Data were collected from dual-energy X-ray absorptiometry and indirect calorimetry. Blood was taken at baseline and at 2 months and assayed for adipokines, lipids, and insulin resistance parameters. The change in circulating fatty acid-binding protein 4 levels were inversely correlated with total weight loss (p<0.02) and lean mass loss (p<0.01), but not with fat mass loss. Retinol-binding protein 4 levels did not track with any measure of body composition. Changes in leptin levels were found to correlate with weight loss (p<0.02), fat loss (p<0.03), and lean mass loss (p<0.05). Fatty acid-binding protein 4 levels increased and retinol-binding protein 4 levels did not change during moderate weight loss in obese women with metabolic syndrome; however, several other risk factors for type 2 diabetes and cardiovascular disease did improve with weight loss., (© Georg Thieme Verlag KG Stuttgart · New York.)

Objective: To compare the effects of protein vs. simple sugars on weight loss, body composition, and metabolic and endocrine parameters in polycystic ovary syndrome (PCOS)., Design: A 2-month, free-living, randomized, single-blinded study., Setting: University PCOS clinic., Patient(s): Thirty-three patients with PCOS., Intervention(s): To achieve a final energy reduction of 450 kcal/day, first the daily energy intake was reduced by 700 kcal; then a 240-kcal supplement containing either whey protein or simple sugars was added., Main Outcome Measure(s): Changes in weight, fat mass, fasting glucose and insulin, plasma lipoproteins, and sex steroids., Result(s): Twenty-four subjects (13 in the simple sugars group and 11 in the protein group) completed the study. The protein group lost more weight (-3.3 +/- 0.8 kg vs. -1.1 +/- 0.6 kg) and more fat mass (-3.1 +/- 0.9 kg vs. -0.5 +/- 0.6 kg) and had larger decreases in serum cholesterol (-33.0 +/- 8.4 mg/dL vs. -2.3 +/- 6.8 mg/dL), high-density lipoprotein cholesterol (-4.5 +/- 1.3 mg/dL vs. -0.4 +/- 1.3 mg/dL), and apoprotein B (-20 +/- 5 mg/dL vs. 3 +/- 5 mg/dL)., Conclusion(s): In patients with PCOS, a hypocaloric diet supplemented with protein reduced body weight, fat mass, serum cholesterol, and apoprotein B more than the diet supplemented with simple sugars.

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.