Long-Term Study Shows Diet Drinks Comparable to Water for Weight Management

The research, led by Professor Jo Harrold of the University of Liverpool and Professor Jason Halford, formerly from the same university and now at the University of Leeds, was funded by the American Beverage Association, though the study team maintained full control over the study's design and reporting.

Findings published in the British Journal of Nutrition indicate that NNS drinks containing aspartame, acesulfame potassium, and sucralose performed similarly to water in aiding weight loss and maintenance. The SWITCH trial enrolled 493 adults with overweight or obesity who participated in a structured behavioral weight management program, randomly assigned to consume either water or commercially available diet beverages. Sweetener consumption levels remained within the safe limits set by the European Food Safety Authority (EFSA).

Results showed that weight loss after two years was statistically similar for both groups, with losses of −4.8 kg for the NNS beverage group and −3.7 kg for the water group. Participants in both categories maintained their weight reductions and saw improvements in waist and hip circumference, body composition, and metabolic markers. No clinically significant differences were found in blood pressure or cholesterol levels related to long-term consumption of the sweeteners compared to water. Both groups experienced a reduction in sugar intake, with a slightly larger decrease for those consuming NNS beverages.

This study addresses recent guidelines from the World Health Organization (WHO) that suggested caution regarding the use of non-sugar sweeteners for weight control due to limited observational data. The SWITCH trial provides robust randomized evidence that may influence future global health recommendations.

Professor Harrold remarked that these findings dispel concerns about sweeteners affecting appetite or leading to weight gain, providing a solid basis for recommendations. The SWITCH trial was designed to explore how reducing dietary sugar impacts weight management and whether replacing sugar with NNS affects appetite regulation. These latest results build on earlier findings published in the International Journal of Obesity in 2023.

Professor Halford suggested that the study fills a significant gap in international debate about diet drinks, demonstrating that NNS beverages can effectively substitute for sugar-sweetened options and perform similarly to water in weight management over a two-year period. The paper, titled 'Effect of non-nutritive sweetened beverages versus water on body weight: long-term results of a randomized controlled trial,' was published in the British Journal of Nutrition.