Findings from the SWITCH Study 52-Week Active Weight Management Phase

A new study, “Non-Nutritive Sweetened Beverages Versus Water After a 52-week Weight Management Program: A Randomized Controlled Trial,” set out to compare the effects of non-nutritive sweetened (NNS) beverages and water on body weight. As part of the larger SWITCH study, the current study was published in the Obesity Journal, and reports results following both the 12-week active weight loss and 40-week weight maintenance phases. The results were recently presented at The Obesity Society’s Obesity Week conference.

Key findings from the study include:

• Weight loss was consistently greater with the NNS beverages group compared to water.
• The maximum weight loss was reached at week 36 with NNS beverages and week 44 with water.
• Both groups started regaining weight after these timepoints, but the NNS beverage group regained weight at a slower rate than the water group.
• Activity levels increased from baseline with the non- nutritive sweetened beverages group.

In the study, the authors report that the greatest rate of weight loss occurred during the first 12 weeks of the trial in both groups. Weight loss appeared to be greater with non-nutritive sweetened (NNS) beverages compared with water from the beginning of the trial. Maximum weight loss was reached at week 44 with water and week 36 with NNS beverages. Both groups started to regain weight after these timepoints, with a slower rate of increase in the NNS beverages group compared with the water group.

At week 52, both groups had significant reductions in body weight from baseline, with a mean weight change of –6.1 kg (-13.4 lbs.) with water versus –7.5 kg (-16.5 lbs.) with NNS beverages for the primary analysis using the complete cases data set. There was a significant difference in the changes from baseline between the groups, as the weight loss with NNS beverages was significantly greater than weight loss with water.

In primary analyses using the complete cases data set, baseline waist circumference had a significant effect on week-52 waist measurement, while both baseline hip circumference and assigned NNS beverages had a significant effect on week-52 hip measurements. There was a significant difference between groups in the changes in high-density lipoprotein cholesterol, driven by a modest increase from baseline in the NNS beverages group (0.0 vs. 0.1 mmol/l). There were no significant differences between groups for the changes in the other biomarkers assessed.

There were no significant changes in hunger consumption from baseline in either treatment group, while sweetener consumption (caloric or non-caloric) was significantly reduced from baseline in the water group, but not the NNS beverages group (–13.1 vs. +1.2 score points), resulting in a statistically significant difference between them, as expected. Sugar consumption was significantly reduced from baseline to a similar extent in both groups. Activity levels, measured as the average number of steps taken per day over 1 week, decreased with water but increased significantly from baseline with NNS beverages at week 52; however, the difference between the groups was not significant.

Overall, the authors concluded that the difference in body weight between water and NNS beverages at the end of this phase was non-equivalent. In next steps, the final voluntary 52-week period of unassisted weight maintenance in this trial will assess whether the discontinuation of routine nutrition awareness visits will have an impact on further maintaining weight loss or preventing weight gain in both groups.

This publication was presented by Jason Halford on October 16, 2023 at Obesity Week in Dallas, Texas.

Conclusion: During a 52-week behavioral weight management program, water and NNS beverages were non-equivalent, with weight loss maintained to a statistically greater extent with NNS beverages compared with water.