The global burden of obesity and type 2 diabetes (T2D) has intensified in the recent decades, driven in part by increased consumption of energy-dense beverages such as sugar-sweetened beverages (SSBs). In response, many individuals have adopted diet beverages (DBs) as a perceived healthier alternative, aiming to achieve weight loss without added caloric intake. However, the metabolic implications of long-term consumption of DB remain controversial. While DBs offer a low-calorie sweetened option, their role in energy balance, insulin sensitivity, and weight regulation continues to be debated.
Water, in contrast, is universally recommended as the ideal beverage during weight management interventions. Observational and interventional studies suggest that water consumption may support reductions in energy intake and improve markers of metabolic health. Yet, few studies have directly compared the metabolic outcomes of replacing DBs with water, particularly in the context of structured weight loss programs.
A pivotal 24-week randomized controlled trial by Madjd et al., investigated this question among overweight and obese women who were habitual consumers of DBs. The participants underwent a structured, hypoenergetic weight-loss program and were randomized to either replace DBs with water or continue DB consumption post-lunch five times per week. The study demonstrated that substituting water for DBs led to significantly greater weight loss (–8.8 kg vs. –7.6 kg, p = 0.015), as well as superior improvements in insulin resistance (homeostasis model assessment of insulin resistance; HOMA-IR) and 2-hour postprandial glucose levels. These findings provided early evidence that substitution of DB with water after the main meal may enhance metabolic benefits during active weight loss interventions [1].
Building on this foundation, Nasr et al., extended the research by evaluating the long-term durability of such an intervention. In their 18-month randomized clinical trial presented at the American Diabetes Association (ADA) 85th Scientific Sessions, June 20–23, 2025, participants who had completed a 6-month weight loss phase were followed through a 12-month maintenance period. The study compared outcomes between those who continued DB consumption and those who replaced DBs with water five times per week post-lunch and demonstrated the benefits of weight loss and diabetes remission with replacement of DB with water after the main meals (see Graphic) [2].
(Source: 1. Madjd A, Taylor MA, Delavari A, et al. Effects on weight loss in adults of replacing diet beverages with water during a hypoenergetic diet: A randomized, 24-wk clinical trial. Am J Clin Nutr. 2015;102(6):1305-12. 2. Nasr, M., Madjd, A., Farshchi, H. R., et al. 586‑P: Effects of replacing diet beverages with water on sustained weight loss and type 2 diabetes remission—An 18‑month randomized clinical trial [Poster abstract]. Diabetes. 2025; 74(Suppl 1), 586‑P. Doi:10.2337/db25‑586‑P)