The effect of green tea supplementation on obesity: A systematic review and dose–response meta‐analysis of randomized controlled trials

Abstract

The effects of green tea (GT) in obese subjects have been evaluated in different studies, but no consensus has been obtained due to the heterogeneity of the results. The dosage, the type of extract, and the duration of the intervention are the main contributors to the heterogeneity of the results. Therefore, the present systematic review and meta-analysis aimed to evaluate the efficacy and dose-response relationship of GT. Several databases were searched from inception to September 2019 to identify clinical trials that examined the influence of GT supplements on obesity indices in humans. Combined results using the random-effects model indicated that body weight (WMD: −1.78 kg, 95% CI: −2.80, −0.75, p = .001) and body mass index (BMI) (WMD: −0.65 kg/m 2 , 95% CI: −1.04, −0.25, p = .001) did change significantly following GT administration. The reduction in waist circumference (WC) after GT consumption was significant in subjects in trials employing GT ≥800 mg/day (WMD: −2.06 cm) and with a treatment duration <12 weeks (WMD: −2.39 cm). Following the dose-response evaluation, GT intake did alter body weight, with a more important reduction when the GT dosage was <500 mg/day and the treatment duration was of 12 weeks. The results of present meta-analysis study support the use of GT for the improvement of obesity indices. Thus, we suggest that the use of GT can be combined with a balanced and healthy diet and regular physical exercise in the management of obese patients. K E Y W O R D S body mass index, dose-response, green tea, meta-analysis, obesity, weight 1 | INTRODUCTION Obesity is an important public health problem and a major contributor to the health burden globally (OECD, 2019). The presence of obesity significantly increases one's risk of non-communicable diseases, for example, diabetes mellitus, cardiovascular disease and cancer (Gaman, Epingeac, & Gaman, 2019; Goossens, 2017). According to the World Health Organization (WHO), obesity is characterized by an abnormal or excessive fat accumulation and is diagnosed clinically based on values of the body mass index (BMI) (kg/m 2) > 30 kg/m 2 (WHO, 2018). Since 1975, the prevalence of obesity has nearly tripled, with almost one-third of the world population being obese (Forse & Kissee, 2020). In 2016, 39% of the adults aged >18 years were reportedly overweight and 13% were obese (WHO, 2018). Obesity is a multifactorial chronic disease whose development results from an imbalance between the energy intake and expenditure

Metabolic Impact of Flavonoids Consumption in Obesity: From Central to Peripheral

“…In humans and animal models, flavanols or flavanols-rich foods (mainly, cocoa or tea derivates) have demonstrated the ability to reduce body weight, decrease waist circumference and fat percentages, improve glucose metabolism in individuals with type 2 diabetes, obesity or MetS and increase energy expenditure [ 75 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 ]. One of the most described molecular mechanism underlying theses effects are the activation of the AMPK enzyme [ 140 ].…”

“…In humans, some studies described the capacity of green tea to reduce body weight and abdominal fat accumulation [ 162 , 163 ], influence on the body fat mass index, waist circumference, total fat mass and energy expenditure through the induction of browning or BAT activity [ 164 , 165 , 166 ] but also to regulate ghrelin secretion and adiponectin levels, to control appetite and decrease nutrient absorption [ 135 , 167 ].…”

Daily Consumption of Coffee and Eating Bread at Breakfast Time Is Associated with Lower Visceral Adipose Tissue and with Lower Prevalence of Both Visceral Obesity and Metabolic Syndrome in Japanese Populations: A Cross-Sectional Study

“…Alternatively, there have been many studies on the association between green tea (which also contains caffeine) and metabolism; consumption of the catechins found in green tea reduced abdominal fat accumulation [ 22 , 23 ] and improved biomarkers of metabolic syndrome [ 22 , 23 ]. However, a Cochrane review proved that the weight loss in adults who consumed green tea was not statistically significant and was not likely to be clinically important [ 24 ].…”

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

“…However, this study failed to find considerable improvement in clinical characteristics, oxidative stress, inflammatory markers, and circulating endothelial progenitor cells (EPCs) number in CKD requiring dialysis [126]. Recent systemic review and meta-analysis suggested that green tea could be beneficial in the management of obesity [127]. It demonstrated that the administration of green tea significantly reduced body weight (WMD: −1.78 kg, 95% CI: −2.80, −0.75, p = 0.001) and body mass index (BMI) (WMD: −0.65 kg/m 2 , 95% CI: −1.04, −0.25, p = 0.001).…”