Non-nutritive sweetened beverages versus water after a 52-week weight management programme: a randomised controlled trial

Background/objective: Sugar-sweetened beverages are a substantial source of dietary sugar that can contribute to weight gain and the risk of type 2 diabetes. Dietary guidelines recommend non-nutritive sweetened (NNS) beverages to reduce sugar consumption, however, there is a need for long-term randomised controlled trials on their use. We aimed to compare the effects of NNS beverages and water on body weight during weight loss and maintenance in a behavioural weight management programme. Methods: In this parallel-group, open-label, controlled equivalence trial, adults with a BMI of 27–35 kg/m who regularly consumed cold beverages were randomised 1:1 to water or NNS beverages. Participants underwent a group behavioural weight management programme comprising weekly (during the 12-week weight-loss phase) then monthly (during the 40-week weight-maintenance phase) meetings. The primary endpoint was weight change at week 52 (equivalence: two-sided P > 0.05). Secondary endpoints included changes in anthropometrics, cardiometabolic risk factors, appetite and activity levels. Results: Of 493 participants randomised (water: n = 246; NNS beverages: n = 247), 24.1% were NNS-naïve. At week 52, water and NNS beverages were non-equivalent, with significantly greater weight loss in the NNS beverages group. Participants consuming water maintained a weight loss of 6.1 kg over 52 weeks versus 7.5 kg with NNS beverages (difference [90% CI]: 1.4 kg [–2.6, –0.2]; p < 0.05). Conclusions: During a 52-week behavioural weight management programme, water and NNS beverages were non-equivalent, with weight loss maintained to a statistically greater extent with NNS beverages compared with water. However, this difference was not clinically significant. Clinical trial registration: This trial is registered with ClinicalTrials.gov: NCT02591134