Nonnutritive sweetened beverages and water may be associated with similar reductions in body weight through 104 weeks among adults participating in a behavioral weight-management program.
In the parallel-group, open-label SWITCH trial, researchers randomly assigned 1:1 493 adults aged 18 to 65 years with a body mass index of 27 to 35 to consume at least 2 330-mL servings per day of water (n = 246) or nonnutritive sweetened (NNS) beverages (n = 247). The program comprised a 12-week active weight-loss phase with weekly behavioral sessions, a 40-week assisted weight-maintenance phase with monthly sessions, and a voluntary 52-week extension without weight-management sessions.
The researchers assessed change in body weight from baseline to week 104, waist and hip circumference, body composition, glycemic measures, lipids, liver biomarkers, hunger, and sugar and sweetener consumption. The primary analysis included participants with body-weight measurements at baseline and week 104, with additional analyses using multiple imputation and last observation carried forward to account for missing data.
Among the 220 participants who completed week 104, body weight decreased by 3.7 kg from a mean baseline weight of 89.9 kg in the water group and by 4.8 kg from 89.4 kg in the NNS beverage group. The between-group difference was not statistically significant, and the researchers reported equivalent weight change between groups. Analyses using multiple imputation and last observation carried forward yielded similar findings.
Weight declined most rapidly during the initial 12-week weight-loss phase in both groups. Body weight reached its lowest point at week 44 in the water group and week 36 in the NNS beverage group before gradually increasing, but remained significantly below baseline through week 104 in both groups. After adjustment for baseline weight, beverage assignment was not significantly associated with body weight at week 104. Age, sex, measurement location, and prior NNS beverage consumption also were not significantly associated with week-104 weight.
Waist and hip circumference decreased from baseline in both groups, without statistically significant between-group differences. Among 48 participants who underwent dual-energy x-ray absorptiometry, fat mass, fat-free mass, and android and gynoid fat measures decreased in both groups with no statistically significant differences.
Some metabolic outcomes differed between groups at week 104. The water group had greater reductions in glycated hemoglobin and diastolic blood pressure, which were not deemed clinically meaningful, whereas total cholesterol increased in the NNS beverage group relative to the water group. Sample sizes for some biomarker analyses were also small.
Hunger increased slightly in both groups without a statistically significant difference. Sugar consumption decreased significantly from baseline in both groups, also without a statistically significant difference between groups. Sweetener consumption decreased substantially among participants assigned to water but remained mostly unchanged among those assigned to NNS beverages.
The researchers noted several limitations. Among the 493 participants who initiated treatment, just 220 completed week 104. They cited the COVID-19 pandemic, the 2-year study duration, and the voluntary nature of the final extension as potential contributors to attrition. The study was conducted at a single site in England, and race and ethnicity data were not collected, potentially limiting generalizability.
“Importantly, both groups maintained significant weight loss up to week 104,” wrote lead study author Joanne A. Harrold, of the Department of Psychology at the University of Liverpool, and colleagues.
Full disclosures of the study authors can be found in the study.
Source: British Journal of Nutrition
