Scientists are to investigate the brain responses of people on Atkins-type diets in a bid to find the key to successful weight loss, it emerged.

Researchers will examine how the appetite-controlling areas of the brain respond when people embark on the popular but controversial low-carbohydrate diets.

They hope this will help them develop healthy weight loss diets which reduce the likelihood of snacking and are more effective than some other diet trends.

The project, which is being jointly undertaken by Aberdeen’s Rowett Research Institute, Aberdeen University, and the city’s Robert Gordon University (RGU), is now recruiting overweight men aged 50 or over to take part in the nine-week residential study. They will be put on different diets and have regular scans at Aberdeen University to reveal how their brain responds during the study.

Dr Alex Johnstone of the Rowett Institute, who is leading the project, said: “Many scientists now accept that weight loss on high-protein, low-carbohydrate diets is because people satisfy their hunger after eating less calories than they would normally eat. This has stimulated our interest in the mechanisms that control appetite and the feeling of being full.

“We know that when people eat low-carbohydrate diets, within a relatively short time their body has to switch from using glucose as a fuel to using a by-product of fat metabolism called ketone bodies. Ketone bodies are appetite-suppressing and this may be because they affect the appetite centres in the brain.”

Dr Johnstone added that studying such mechanisms could help them develop healthy weight-loss diets which are more satisfying and reduce hunger pangs. “This means people would be less likely to snack and break their diet,” she said.

Dr Andy Welch, of Aberdeen University, said: “The scans we take during this study will show if the appetite centres in the volunteers’ brains respond differently depending on the weight-loss diets they are eating. This in turn will indicate whether the carbohydrate levels in the high-protein diets are important.”

Professor Iain Broom of RGU, an expert in the clinical treatment of obesity, said: “This study will further develop our understanding of the processes of body weight regulation and should help us to refine weight-loss protocols and provide appropriate targeting of treatment to obese patients.”

The study is being funded by the Scottish Executive and the Chief Scientist Office. It forms part of a ?2.5 million research programme by the Rowett Institute into Obesity and metabolic health.