Water Intake and Adiposity Outcomes among Overweight and Obese Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Water consumption is believed to be a key factor in weight management strategies, yet the existing literature on the subject yields inconsistent findings. To systematically assess the scientific evidence regarding the effect of water intake on adiposity, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) among overweight and obese populations. Methods: PubMed and Embase were searched for relevant articles published up to December 2023. The summary weighted mean difference (WMD) and 95% confidence interval (CI) were estimated using the DerSimonian-Laird random-effects model. Results: In this meta-analysis of eight RCTs, interventions to promote water intake or to substitute water for other beverages as compared to the control group resulted in a summary WMD of -0.33 kg (95% CI = -1.75-1.08, I2 = 78%) for body weight, -0.23 kg/m2 (95% CI = -0.55-0.09, I2 = 0%) for body mass index (BMI), and 0.05 cm (95% CI = -1.20-1.30, I2 = 40%) for waist circumference (WC). Among RCTs substituting water for artificially sweetened beverages, summary WMD was 1.82 kg (95% CI = 0.97-2.67, I2 = 0%) for body weight and 1.23 cm (95% CI = -0.03-2.48, I2 = 0%) for WC. Conversely, among RCTs substituting water for sugar-sweetened beverages, summary WMD was -0.81 kg (95% CI = -1.66-0.03, I2 = 2%) for body weight and -0.96 cm (95% CI = -2.06-0.13, I2 = 0%) for WC. Conclusions: In conclusion, water intake may not significantly impact adiposity among overweight and obese individuals. However, replacing sugar-sweetened beverages with water might offer a modest benefit in inducing weight loss.