1.
The influence of fasting and energy-restricted diets on leptin and adiponectin levels in humans: A systematic review and meta-analysis.
Varkaneh Kord, H, M Tinsley, G, O Santos, H, Zand, H, Nazary, A, Fatahi, S, Mokhtari, Z, Salehi-Sahlabadi, A, Tan, SC, Rahmani, J, et al
Clinical nutrition (Edinburgh, Scotland). 2021;(4):1811-1821
Abstract
BACKGROUND & AIMS Fasting and energy-restricted diets have been evaluated in several studies as a means of improving cardiometabolic biomarkers related to body fat loss. However, further investigation is required to understand potential alterations of leptin and adiponectin concentrations. Thus, we performed a systematic review and meta-analysis to derive a more precise estimate of the influence of fasting and energy-restricted diets on leptin and adiponectin levels in humans, as well as to detect potential sources of heterogeneity in the available literature. METHODS A comprehensive systematic search was performed in Web of Science, PubMed/MEDLINE, Cochrane, SCOPUS and Embase from inception until June 2019. All clinical trials investigating the effects of fasting and energy-restricted diets on leptin and adiponectin in adults were included. RESULTS Twelve studies containing 17 arms and a total of 495 individuals (intervention = 249, control = 246) reported changes in serum leptin concentrations, and 10 studies containing 12 arms with a total of 438 individuals (intervention = 222, control = 216) reported changes in serum adiponectin concentrations. The combined effect sizes suggested a significant effect of fasting and energy-restricted diets on leptin concentrations (WMD: -3.690 ng/ml, 95% CI: -5.190, -2.190, p ≤ 0.001; I2 = 84.9%). However, no significant effect of fasting and energy-restricted diets on adiponectin concentrations was found (WMD: -159.520 ng/ml, 95% CI: -689.491, 370.451, p = 0.555; I2 = 74.2%). Stratified analyses showed that energy-restricted regimens significantly increased adiponectin (WMD: 554.129 ng/ml, 95% CI: 150.295, 957.964; I2 = 0.0%). In addition, subsequent subgroup analyses revealed that energy restriction, to ≤50% normal required daily energy intake, resulted in significantly reduced concentrations of leptin (WMD: -4.199 ng/ml, 95% CI: -7.279, -1.118; I2 = 83.9%) and significantly increased concentrations of adiponectin (WMD: 524.04 ng/ml, 95% CI: 115.618, 932.469: I2 = 0.0%). CONCLUSION Fasting and energy-restricted diets elicit significant reductions in serum leptin concentrations. Increases in adiponectin may also be observed when energy intake is ≤50% of normal requirements, although limited data preclude definitive conclusions on this point.
2.
Efficacy of Intermittent or Continuous Very Low-Energy Diets in Overweight and Obese Individuals with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analyses.
Huang, YS, Zheng, Q, Yang, H, Fu, X, Zhang, X, Xia, C, Zhu, Z, Liu, YN, Liu, WJ
Journal of diabetes research. 2020;:4851671
Abstract
OBJECTIVE This study is aimed at investigating the efficacy of a very low-energy diet (VLED) in overweight and obese individuals with type 2 diabetes mellitus (T2DM). METHODS We thoroughly searched eight electronic resource databases of controlled studies concerning the efficacy and acceptability of intermittent or continuous VLEDs in patients with T2DM compared with other energy restriction interventions. RESULTS Eighteen studies (11 randomized and seven nonrandomized controlled trials) with 911 participants were included. The meta-analyses showed that compared with a low-energy diet (LED) and mild energy restriction (MER), VLED is superior in the reduction of body weight (mean difference (MD) MDLED = -2.77, 95% confidence interval (CI) CILED = -4.81 to - 0.72, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, I 2 = 0%) and TG level (MD = -0.25, 95%CI = -0.55 to 0.06, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, I 2 = 0%) and TG level (MD = -0.25, 95%CI = -0.55 to 0.06, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39, P LED = 0.008; MDMER = -6.72, 95%CIMER = -10.05 to - 3.39. CONCLUSION Dietary intervention through VLEDs is an effective therapy for rapid weight loss, glycemic control, and improved lipid metabolism in overweight and obese individuals with T2DM. Thus, VLEDs should be encouraged in overweight and obese individuals with T2DM who urgently need weight loss and are unsuitable or unwilling to undergo surgery. As all outcome indicators have low or extremely low quality after GRADE evaluation, further clinical trials that focus on the remission effect of VLEDs on T2DM are needed.