A 104-week clinical trial found that diet drinks are equivalent to water for long-term weight management. It was the longest, most comprehensive randomized controlled trial to ever study non-nutritive sweetened (NNS) soft drinks. NNS are low- or no- calorie sweeteners.
The research was conducted by scientists from the Univ. of Liverpool and the Univ. of Leeds. It was funded by the American Beverage Association. But the team had full control of the analysis and reporting of their findings, and their work was peer-reviewed. The study was published in the British Journal of Nutrition.
The trial followed almost 500 adults who were randomly assigned to drink either water or diet drinks daily. The results suggest diet drinks don’t disrupt appetite regulation or harm metabolic health. The study found that both groups lost weight and sustained that weight loss. Both groups had improved metabolic biomarkers. There was no clinical difference in the blood pressure or cholesterol of the people who drank diet soda and the people who drank water. Both groups ate less sugar as the study went on; the diet soda drinkers ate less sugar than the water drinkers.
Prof. Jason Halford of the Univ. of Leeds said, “This study provides the long term clinical evidence that has been missing from international discussions. For people trying to manage their weight, non nutritive sweetened beverages offer an effective alternative to sugar sweetened drinks — and perform equivalently to water over two years.”
Most of the people in the study lost the majority of their weight in the first three months. They reached their lowest average weight during the first year. Both groups regained most weight but kept most of it off. There was no statistical difference between the two groups. Both groups were given healthy diet advice and weekly behavioral sessions for the first 12 weeks. They also had monthly meetings for 40 weeks.
In 2023, the World Health Organization (WHO) recommended against using NNS as a way to control weight or lower chronic disease risk. The WHO recommendation was based on observational studies. While the new trial doesn’t answer every concern that the WHO hadn’t answered, it does address many problems, as it was such a long study and so controlled.
