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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.
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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.
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Extended calorie restriction suppresses overall and specific food cravings: a systematic review and a meta-analysis.
Kahathuduwa, CN, Binks, M, Martin, CK, Dawson, JA
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2017;(10):1122-1135
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Abstract
BACKGROUND Multiple studies have concluded that calorie restriction for at least 12 weeks is associated with reduced food cravings, while others have shown that calorie restriction may increase food cravings. We addressed this ambiguity in a systematic review and meta-analysis. METHODS We searched for studies conducted on subjects with obesity, implemented calorie restriction for at least 12 weeks and measured food cravings pre-intervention and post-intervention. Our final eight studies mostly used the Food Craving Inventory. Other comparable methods were converted to a similar scale. We used the duration ≥12 weeks, but closest to 16 weeks for studies with multiple follow-ups and performed DerSimonian-Laird random-effects meta-analyses using the 'metafor' package in r software. RESULTS Despite heterogeneity across studies, we observed reductions in pooled effects for overall food cravings (-0.246 [-0.490, -0.001]) as well as cravings for sweet (-0.410 [-0.626, -0.194]), high-fat (-0.190 [-0.343, -0.037]), starchy (-0.288 [-0.517, -0.058]) and fast food (-0.340 [-0.633, -0.048]) in the meta-analysis. Baseline body weight, type of intervention, duration, sample size and percentage of female subjects explained the heterogeneity. CONCLUSIONS Calorie restriction is associated with reduced food cravings supporting a de-conditioning model of craving reductions. Our findings should ease the minds of clinicians concerned about increased cravings in patients undergoing calorie restriction interventions.
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Effects of Different Dietary Interventions on Blood Pressure: Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Gay, HC, Rao, SG, Vaccarino, V, Ali, MK
Hypertension (Dallas, Tex. : 1979). 2016;(4):733-9
Abstract
Previous studies have shown beneficial effects of individual dietary approaches for blood pressure (BP) control, but their relative effectiveness is not well established. We performed a systematic review of published dietary pattern interventions and estimated the aggregate BP effects through meta-analysis. PubMed, EMBASE, and Web of Science databases were searched to identify studies published between January 1, 1990 and March 1, 2015. Studies meeting specific inclusion and exclusion criteria were selected. Data were pooled using random effects meta-analysis models. Twenty-four trials with 23 858 total participants were included. The overall pooled net effect of dietary intervention on systolic BP and diastolic BP was -3.07 mm Hg (95% confidence interval, -3.85 to -2.30) and -1.81 mm Hg (95% confidence interval, -2.24 to -1.38), respectively. The Dietary Approaches to Stop Hypertension diet had the largest net effect (systolic BP, -7.62 mm Hg [95% confidence interval, -9.95 to -5.29] and diastolic BP, -4.22 mm Hg [95% confidence interval, -5.87 to -2.57]). Low-sodium; low-sodium, high-potassium; low-sodium, low-calorie; and low-calorie diets also led to significant systolic and diastolic BP reductions, whereas Mediterranean diet participants experienced a significant incremental reduction in diastolic but not systolic BP. Subgroup analysis also showed important variations in effectiveness based on duration, size, and participant demographics. In conclusion, dietary modifications are associated with clinically meaningful, though variable, reductions in BP. Some diets are more effective than others and under different circumstances, which has important implications from both clinical and public health perspectives.
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Combination of very low energy diets and pharmacotherapy in the treatment of obesity: meta-analysis of published data.
Koutroumanidou, E, Pagonopoulou, O
Diabetes/metabolism research and reviews. 2014;(3):165-74
Abstract
Obesity has reached epidemic proportions globally, with more than 1 billion adults overweight - at least 300 million of them clinically obese - and is a major contributor to the global burden of chronic disease (heart disease and diabetes) and disability. The aim of the study was to perform a systematic review and meta-analysis of published data on the combination of very low energy diets also known as very low calorie diets and pharmacotherapy for its effectiveness in the treatment of obesity. A MEDLINE (Pubmed) search from 1970 to 2009 using multiple combinations of the relevant terms was carried out; the matching articles were also searched for additional references. Meta-analysis tools were used to summarize results. Only randomized controlled trials that compared pharmacotherapy with placebo after a very low energy diet period were selected, and six articles were finally considered to be appropriate for evaluation. The combination of very low energy diet and pharmacotherapy was found to be effective for people with obesity in clinical trials. The net effect of 6.1 kg placebo subtracted weight loss after 1 year represents a clinically meaningful result that is comparable with the effect of drugs given at the start of a weight loss programme. The present meta-analysis contributes to the understanding that combination therapies are expected to achieve greater weight loss than monotherapy; grasping this understanding, researcher has introduced newer anti-obesity pharmacological approaches have embraced combination therapies.
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Efficacy of hypocaloric parenteral nutrition for surgical patients: a systematic review and meta-analysis.
Jiang, H, Sun, MW, Hefright, B, Chen, W, Lu, CD, Zeng, J
Clinical nutrition (Edinburgh, Scotland). 2011;(6):730-7
Abstract
BACKGROUND AND AIMS Hypocaloric parenteral nutrition is an underfeeding strategy that lowers energy intake to around 20 kcal/kg/d. It is believed to achieve benefits by modulating metabolic responses and alleviating hyperglycemia. This study aims to systematically review the clinical efficacy of hypocaloric parenteral nutrition on surgical patients. METHODS Medline, SCI, Embase, Cochrane Library, Chinese Biomedicine Database (CBM) and China Knowledge Resource Integrated Database (CNKI) were searched for studies published before July 1, 2010. Randomized control trials (RCTs) that compared hypocaloric PN with standard or higher energy PN in surgical patients were identified and included. Methodological quality assessment was based on Cochrane Reviewers' Handbook and modified Jadad's Score Scale. Statistical software RevMan 5.0 was used for meta-analysis. RESULTS Five trials met all inclusion criteria and were included in the final meta-analysis. There were significant reductions in infectious complications (RR, 0.60; 95%CI 0.39-0.91, P = 0.02; I(2) = 38%) and length of hospitalization (LOS) associated with receiving hypocaloric PN (MD-2.49 days, 95%CI -3.88 to -1.11, P = 0.0004; I² = 48%). Stratified analysis of the smaller trials (<60) and larger trials demonstrated that the heterogeneity between trials was mainly associated with sample size. When smaller trials were excluded, hypocaloric PN was associated with reduction in infectious complications (RR, 0.21, 95%CI 0.06-0.72, P = 0.01, I2 = 0%) and shortening of LOS (MD, -2.32 days, 95%CI -3.72 to -0.93, P = 0.001, I² = 0%). CONCLUSION Hypocaloric parenteral nutrition may reduce infectious complications and the length of hospitalization in post-operative patients. However, this conclusion is tentative due to patient type and sample size. Furthermore, in terms of hypocaloric PN, the actual energy amount still varies a great deal (from 15 kcal/kg/d to 20 kcal/kg/d). This suggests that further research, including larger randomized clinical trials is required.