Soy may be a suitable food for anti-obesity efforts because of its high protein and isoflavone content. We conducted this meta-analysis to evaluate potential effects of soy and soy isoflavones on weight, waist circumference, and fat mass. PubMed, MEDLINE, Scopus, EMBASE, and Cochrane databases were searched. Twenty-four trials with soy and 17 trials with isoflavones passed the eligibility stage. According to the results, soy showed no overall statistically significant effect on weight, waist circumference, or fat mass, but a significant increasing effect on weight was observed in some circumstances: for instance, in obese subjects [mean difference (MD): 0.80 kg; 95% CI: 0.15, 1.45 kg; = 0.02], with ingestions of ≥40 g soy protein/d (MD: 0.94 kg; 95% CI: 0.11, 1.77 kg; = 0.03), with short-term applications (1-3 mo) (MD: 0.45 kg; 95% CI: 0.05, 0.86 kg; = 0.03), and when soy was compared with meat (MD: 0.36 kg; 95% CI: 0.09, 0.64 kg; = 0.03) and whey protein (MD: 1.53 kg; 95% CI: 0.10, 2.96 kg; = 0.04). In contrast to the effects of soy on weight, soy significantly decreased waist circumference in older ages (MD: -0.36 cm; 95% CI: -0.71, -0.01 cm; = 0.04), in women (MD: -0.32 cm; 95% CI: -0.57, -0.08 cm; = 0.01), and at doses of<40 g soy protein/d (MD: -0.31 cm; 95% CI: -0.57, -0.05 cm; = 0.02). Isoflavone studies, conducted only in women, showed that isoflavones may reduce body mass index (BMI; in kg/m) (MD: -0.26; 95% CI: -0.55, 0.04; = 0.085), especially in dosages<100 mg/d (MD: -0.48; 95% CI: -0.90, -0.06; = 0.02) and in intervention periods of 2-6 mo (MD: -0.28; 95% CI: -0.56, 0.00; = 0.053), but no effect was observed in higher doses or longer intervention periods. Also, a trend for reduced BMI after consumption of isoflavones was observed in Caucasians (MD: -0.35; 95% CI: -0.74, 0.04; = 0.08). Overall, results showed that, although soy is the major source of isoflavones, soy and isoflavones may have different impacts on weight status.

Studies have revealed that the timing of macronutrient ingestion may influence body weight and glucose tolerance. We aimed to examine the effect of high protein versus high carbohydrate intake at the evening meal on metabolic parameters of patients with type 2 diabetes. This is a single-blinded, parallel, randomized controlled trial. 96 patients with type 2 diabetes, aged 32-65 years with a mean body mass index (BMI) of 28.5 ± 3.4 kg/m2 were randomly assigned into one of these three groups: Standard evening meal (ST), High carbohydrate evening meal (HC), and High protein evening meal (HP). Then, the patients were followed for 10 weeks. HbA1c, fasting blood glucose (FBG), fasting insulin, insulin resistance, triglyceride, low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C), diastolic blood pressure, body weight, body fat percentage, and waist circumference decreased significantly in all three groups (P < 0.05). HbA1c showed more improvement in the ST compared with the HP group (- 0.45 ± 0.36 vs. - 0.26 ± 0.36). Reductions in BMI and body weight were significantly higher in the ST compared with the HP group (P < 0.05). Reductions in total cholesterol, non-high-density lipoprotein cholesterol (non-HDL-C), and systolic blood pressure were significant in all groups, except for the HP group. Non-HDL-C/HDL-C remained unchanged in all groups. The results of the present study revealed that even distribution of carbohydrates and protein among meals compared with reducing carbohydrates and increasing protein at dinner may have a more beneficial effect on glycemic control of patients with type 2 diabetes.

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Background/Objectives Patients with diabetes mellitus have a lower quality of life and sleep compared with healthy individuals. Nutrition therapy has an important role in the management of diabetes and can improve inflammation and quality of life in patients with diabetes. The present study aimed to evaluate the effect of high‐protein versus high‐carbohydrate intake during evening meal on quality of life, sleep quality, inflammation, and oxidative stress in subjects with type 2 diabetes. Subjects/Methods This is a 10‐week randomized controlled trial. 96 adult patients with type 2 diabetes were assigned into one of the following three groups: standard evening meal (ST), high‐carbohydrate evening meal (HC), and high‐protein evening meal (HP). The effect of these diets was examined on high‐sensitivity C‐reactive protein, malondialdehyde, quality of life, and sleep quality. Results Sleep quality improved significantly in all groups (p < .05). The quality of life and high‐sensitivity C‐reactive protein improved in all groups except for the HP group (p < .05). Serum malondialdehyde level did not change significantly throughout the study (p > .05). Conclusions Small manipulation of protein and carbohydrate distribution among the meals might not affect sleep quality. A diet with an even distribution of macronutrients among the meals or with a higher percentage of carbohydrates in the evenings can improve the quality of life and reduce inflammation in patients with type 2 diabetes, while a diet with a higher percentage of protein in the evenings may not improve it.