University leads diet drinks study to tackle obesity

Close up of a fizzy drink

The University of Liverpool is running the largest ever investigation into artificially sweetened drinks and their effect on weight loss and weight maintenance.

Many people in the UK drink artificially sweetened drinks (such as diet cola or diet lemonade) on a daily basis, but their use is controversial.

With the current emphasis on reducing sugar in the diet, artificially sweetened drinks provide a sugar free alternative to those who still wish to consume sweet drinks. While the benefits of drinking plenty of water are well understood, could drinking artificially sweetened drinks be just as effective when it comes to weight management, or do they promote the consumption of other sweet foods?

The SWITCH study will split willing participants into two groups that receive an identical weight loss programme. One group will receive two artificially sweetened drinks per day and the other group will receive two drinks of water.

Specialist team

The University has gathered a team consisting of professors, medics, researchers and nutritionists for the four year study. The SWITCH team will analyse the diet; body weight, appetite, and physical activity of its participants. It will also investigate to see whether the experience of the programme and ease of weight loss is different between the two groups.

In a smaller sample the SWITCH study will also analyse, body composition and eating behaviour. For those participants who wish to, the team will take blood to analyse biomarkers of health such as cholesterol profiles and insulin levels.

Professor Jason Halford, Principal Investigator for the SWITCH project, said: “An investigation of their effects on appetite and food choice on this scale has never been undertaken. Understanding the effectiveness of artificially sweetened drinks will help shape best practice when it comes to weight management.”

Assessing the best approach

The SWITCH study follows on from research conducted in the USA. Researchers from Colorado University found that when two groups received the same weight loss programme the group that received artificially sweetened drinks lost significantly more weight compared to the group that received water.

Secondly the group that received the artificially sweetened drinks reported greater reductions in feeling hungry than the water group. One of the main aims of the SWITCH study is to understand what could cause such differences, investigating the effects of artificially sweetened drinks on hunger and fullness.

Dr Jo Harrold, a Senior Lecturer in Psychological Sciences, said “The SWITCH study should help us better understand the relationship people have with artificially sweetened drinks. We hope some of the knowledge gained will help people decide what is the best approach to weight management for them.”

“There are many types of drink on the market that contain artificial sweeteners. The SWITCH study will feedback to inform the public whether these drinks are as effective in weight management as water. A large scale trial in the UK will help to inform the public on what drinks they may wish to consume if they are pursuing weight loss goals.”

The SWITCH study will also examine the impact of artificially sweetened drinks on energy intake, liking/wanting of foodstuffs and the mood state of its participants.

For more information about the SWITCH study please visit

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