Solo diets no way to lose weight

Dieting alone is not as effective as in a group

Joining a weight-loss group is less stressful and more effective than dieting alone, research has shown.

A study at Aston University and the Western Human Nutrition Center found lone dieters lost less weight and were more stressed than those in a group.

The researchers suggest weight-loss groups are more successful because dieters benefit from their supportive environment.

Around 90% of people who diet end up putting the weight back on.

Testing for stress

Researchers at Aston University and colleagues studied 60 women over eight weeks.

They were equally divided into three groups: those on no diet, those dieting alone, and those attending the same weight-loss organisation.

The lone dieters could choose any diet they wished, including the Atkins diet.

The researchers tested the women by measuring the amount of stress hormone cortisol present in their saliva.

Results showed women dieting by themselves were far more stressed than women in the other two groups, while women attending the weight-loss group had similar stress levels to those who were not dieting.

Women dieting alone also displayed impaired mental performance when tested on simple computer tasks.

Sharing the problem

According to Dr Green, most women who diet experience increased stress in the first two weeks.

It's true in this case that a problem shared is a problem halved Dr Frankie Phillips, Dietitian, British Nutrition Foundation

Being able to cope through this period is crucial to how well a diet can work, he said.

"Women in a group are more likely to get through this stressful period," he told BBC News Online.

"Organised dieting groups are less stressful due to the group support, regulation and nutritional information that they provide."

Those dieting alone did experience some weight loss, but not as much as those attending weight-loss classes.

Dr Frankie Phillips, a dietitian for the British Nutrition Foundation said dieting can cause stress if people are not eating a balanced diet.

She said it was generally easier for people in groups to stick to their diet, due to 'team spirit'.

"Women don't always have to join a commercial group to get support: they can rely on their family or friends to help them through it."

"It's true in this case that a problem shared is a problem halved."

Dr Green said understanding the effectiveness of weight-loss programs is important as the national obesity rate rapidly increases.

Currently 25% of men and 20% of women in the UK are obese.