The effect of a very low calorie diet on subjective depressive symptoms and anxiety: meta-analysis and systematic review

ObjectiveFew randomized clinical studies have evaluated the impact of diet and physical activity on testosterone levels in obese men with conflicting results. Conversely, studies on bariatric surgery in men generally have shown an increase in testosterone levels. The aim of this study is to perform a systematic review and meta-analysis of available trials on the effect of body weight loss on sex hormones levels.DesignMeta-analysis.MethodsAn extensive Medline search was performed including the following words: ‘testosterone’, ‘diet’, ‘weight loss’, ‘bariatric surgery’, and ‘males’. The search was restricted to data from January 1, 1969 up to August 31, 2012.ResultsOut of 266 retrieved articles, 24 were included in the study. Of the latter, 22 evaluated the effect of diet or bariatric surgery, whereas two compared diet and bariatric surgery. Overall, both a low-calorie diet and bariatric surgery are associated with a significant (P<0.0001) increase in plasma sex hormone-binding globulin-bound and -unbound testosterone levels (total testosterone (TT)), with bariatric surgery being more effective in comparison with the low-calorie diet (TT increase: 8.73 (6.51–10.95) vs 2.87 (1.68–4.07) for bariatric surgery and the low-calorie diet, respectively; both P<0.0001 vs baseline). Androgen rise is greater in those patients who lose more weight as well as in younger, non-diabetic subjects with a greater degree of obesity. Body weight loss is also associated with a decrease in estradiol and an increase in gonadotropins levels. Multiple regression analysis shows that the degree of body weight loss is the best determinant of TT rise (B=2.50±0.98, P=0.029).ConclusionsThese data show that weight loss is associated with an increase in both bound and unbound testosterone levels. The normalization of sex hormones induced by body weight loss is a possible mechanism contributing to the beneficial effects of surgery in morbid obesity.

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The effects of exercise and low-calorie diets compared with low-calorie diets alone on health: a protocol for systematic reviews and meta-analyses of controlled clinical trials

10.21203/rs.3.rs-30600/v1 ◽

2020 ◽

Author(s):

Sara Beigrezaei ◽

Zeinab Yazdanpanah ◽

Sepideh Soltani ◽

Seiedeh Hamideh Rajaei ◽

Sahar Mohseni-Takalloo ◽

...

Keyword(s):

Systematic Review ◽

Weight Loss ◽

Clinical Trials ◽

Meta Analysis ◽

Controlled Clinical Trials ◽

Low Calorie ◽

Low Calorie Diet ◽

Calorie Diet ◽

Meta Analyses

Abstract Background: Exercise and weight loss diets are two independent non-pharmaceutical strategies known to improve several aspects of body composition and health. We plan to systematically review randomized controlled trials investigating weight loss diets alone compared to weight loss diets in conjunction with exercise on energy intake, body weight, body composition, cardiometabolic risk factors, sex hormones, and mental health. Methods and analysis: PubMed/MEDLINE, EMBASE, ISI (Web of sciences), Scopus, and Google Scholar will be searched to retrieve potential controlled clinical trials investigating the effects of exercise in conjunction with weight-loss diets compared with weight-loss diets alone on energy intake, body weight and composition (fat mass, fat-free mass), anthropometrics (waist circumference), cardiometabolic markers, sex hormones [testosterone, estradiol, and sex hormone binding globulin (SHBG)], liver and kidney enzymes (alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), uric acid, blood urea nitrogen (BUN), and glomerular filtration rate (GFR), quality of life, and depression in adults will be included. The weighted mean difference (WMD) and its corresponding 95% confidence intervals (CIs) will be derived using the random effects model. Several subgroup analyses such as gender, age, BMI, exercise protocol, and diet used for weight loss will be conducted to explore possible sources of heterogeneity. Publication bias will be explored by inspecting funnel plots and by conducting asymmetry tests. Overall quality of the evidence will be assessed by using the NutriGrade scoring system, which is designed to judge the overall quality of meta-analyses of clinical trials conducted in the field of nutrition. Discussion: This proposed systematic review and meta-analysis aims to compare the effects of a low-calorie diet with low-calorie diet plus exercise on the risk factors for chronic diseases. We hope this systematic review and meta-analysis will provide valuable information regarding the values which exercise add to weight-loss diets. No primary data are going to be collected; therefore, ethical approval is not required. The resulting manuscripts will be disseminated in peer-reviewed journals and at international and local conferences. Systematic review registration: This protocol in being considered for registration in the International Prospective Register of Systematic Reviews (PROSPERO).

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