The effects of garlic supplementation on weight loss: A systematic review and meta-analysis of randomized controlled trials

Obesity is related to increase in the incidence of morbidity and mortality. Studies have suggested anti-obesity properties of garlic; however, results are inconsistent. This systematic review and meta-analysis is done to summarize the data obtained from available randomized clinical trials on the effect of garlic supplementation on body weight, Body Mass Index (BMI), and Waist Circumference (WC). The online databases of Scopus, PubMed, Google Scholar and Cochrane library were searched until March 2018 for related publications using relevant keywords. Effect sizes of eligible studies were pooled using random-effects models. Cochran's Q-test and I² index were used for assessing heterogeneity. We found 1241 records in our initial search, of which 13 randomized clinical trials (RCTs) with 15 treatment arms were included. Pooled analysis showed that garlic administration might significantly decrease WC (Weighed Mean Difference (WMD): -1.10 cm, 95% CI: -2.13, -0.07, P = 0.03, I² = 0%). However, garlic intervention had no significant effect on body weight (WMD): -0.17 kg, 95% CI: -0.75 to 0.39, P = 0.54, I² = 0%) and BMI (WMD: -0.17 kg/m², 95% CI: -0.52, 0.16, P = 0.30, I² = 44.5%) as compared to controls. From Subgroup analysis, it was ascertained that the effect of garlic supplementation on BMI was significant in trials with duration < 12 weeks (WMD: -0.58 kg/m², 95% CI: -1.08, -0.08, I² = 19.8%, P = 0.02) compared to those with higher duration (>12 weeks). The current meta-analysis results suggest that garlic supplementation seems to reduce waist circumference unlike body weight and BMI.