Missing puzzle pieces of time-restricted-eating (TRE) as a long-term weight-loss strategy in overweight and obese people? A systematic review and meta-analysis of randomized controlled trials.

The efficacy of using time restricted eating (TRE) for weight management and to mitigate metabolic disorders in overweight and obese people remains debatable. This meta-analysis quantified the impact of TRE on weight loss and metabolic health in overweight and obese people. The pooled results were subjected to a random-effects modeling using Hartung-Knapp-Sidik-Jonkman (HKSJ) method. Additionally, subgroup analysis was conducted based on study types, randomized controlled trials (RCTs) vs. non-randomized studies of interventions (NRSIs). Pooled results showed that subjects on TRE regimen (> 4 weeks) achieved a significant weight loss in comparison with unrestricted time regimen (weighted mean difference: -2.32%; 95% CI: -3.50, -1.14%; p < 0.01); however, weight loss was mainly attributed to the loss of lean mass rather than fat mass. The magnitude of weight loss was inversely correlated with daily fasting duration in RCTs. TRE significantly decreased the diastolic blood pressure and fasting insulin. An increase of low-density lipoprotein cholesterol (LDL-C) was observed in the TRE group. Favorable effect of TRE was observed on glucose metabolism but not on lipid profiles independent of weight loss. Hence TRE shall be administered with caution to overweight and obese people who have comorbidities such as dyslipidemia and sarcopenia.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.1974335.

[Effects of different ratios of n-6/n-3 polyunsaturated fatty acid on adiponectin, glycolipid metabolism and antioxidant capacity in high fat-diet fed rats].

OBJECTIVE: To investigate effects of different ratios of n-6/n-3 Polyunsaturated fatty acid(PUFA) on adiponectin, glycolipid metabolism and antioxidant capacity in high fat-diet fed rats. METHODS: Fixty male Wistar rats were randomly divided into control group(CON, 17% energy from fat, n-6/n-3 PUFA=5∶1) and high-fat treatment groups(1∶1 group∶n-6/n-3 PUFA=1∶1, 5∶1 group, n-6/n-3 PUFA=5∶1, 10∶1 group∶ n-6/n-3 PUFA=10∶1 and 20∶1 group∶ n-6/n-3 PUFA=20∶1, 42% energy from fat). Rats were fed for 12 week. Serum glucose and lipid(0, 4, 8 and 12 week) were detected. Antioxidant indexes(0 and 12 week), adiponectin mRNA and protein expressions in epididymal adipose tissues as well as serum adiponectin(12 week) were measured. RESULTS: Baseline data showed no significant inter-group difference(P>0. 05). 1∶1 and 5∶1 showed no significant changes in serum glucose compared with control at all time points(P>0. 05), while 10∶1 and 20∶1 significantly increased it at the 12 th week(P<0. 05). At the 12 th week, total cholesterol(TC) and triglycerides(TG) in high-fat treatment groups were significantly higher than control(P<0. 01), with 20∶1 showing significant increment of TG compared with other high-fat treatment groups(P<0. 01). At the 12~(th) week, glutathione peroxidase and superoxide dismutase content in high-fat treatment groups all decreased significantly compared with control(P<0. 05), and 20∶1 decreased most. Malondialdehyde content significantly increased in high-fat treatment groups(P<0. 05), and 10∶1 increased most. Adiponectin mRNA expression significantly decreased in 20∶1 compared with control, 1∶1 and 5∶1(P<0. 05). Increment of adiponectin protein expression was significantly shown in 5∶1 compared with other high-fat treatment groups(P<0. 05), while it was most obviously decreased in 20∶1(P<0. 05). CONCLUSION: Lower n-6/n-3 PUFA ratios(1∶1 and 5∶1) contributed to improvement of glycolipid metabolism and antioxidant capacity as well as increment of adiponectin expression of rats fed with high-fat diet.

A Moderate Low-Carbohydrate Low-Calorie Diet Improves Lipid Profile, Insulin Sensitivity and Adiponectin Expression in Rats.

Calorie restriction (CR) via manipulating dietary carbohydrates has attracted increasing interest in the prevention and treatment of metabolic syndrome. There is little consensus about the extent of carbohydrate restriction to elicit optimal results in controlling metabolic parameters. Our study will identify a better carbohydrate-restricted diet using rat models. Rats were fed with one of the following diets for 12 weeks: Control diet, 80% energy (34% carbohydrate-reduced) and 60% energy (68% carbohydrate-reduced) of the control diet. Changes in metabolic parameters and expressions of adiponectin and peroxisome proliferator activator receptor γ (PPARγ) were identified. Compared to the control diet, 68% carbohydrate-reduced diet led to a decrease in serum triglyceride and increases inlow density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C) and total cholesterol; a 34% carbohydrate-reduced diet resulted in a decrease in triglycerides and an increase in HDL-cholesterol, no changes however, were shown in LDL-cholesterol and total cholesterol; reductions in HOMA-IR were observed in both CR groups. Gene expressions of adiponectin and PPARγ in adipose tissues were found proportionally elevated with an increased degree of energy restriction. Our study for the first time ever identified that a moderate-carbohydrate restricted diet is not only effective in raising gene expressions of adiponectin and PPARγ which potentially lead to better metabolic conditions but is better at improving lipid profiles than a low-carbohydrate diet in rats.