Organised weight loss groups are the most effective way to diet, according to new research conducted by Aston University’s Dr Mike Green and Nicola Elliman in conjunction with the Western Human Nutrition Center, University of California.

The study (funded by the US Department of Agriculture) measured the stress and mental performance levels of 60 women, including control subjects, women who were dieting on their own and others who were attending organised weight loss groups.

The aim of the study was to examine whether the deficits found in mental performance in dieting are due to the type of weight loss plan used and whether this is related to the amount of stress experienced on each plan.

Previous studies carried out by the Aston research group have consistently found significant impairments in mental performance of women losing weight due to its psychological effects, especially within the first 1 -2 weeks of the diet.

The stress levels of the participants were measured by looking at the amount of the stress hormone cortisol in their saliva. Mental performance was assessed by the completion of simple computer tasks.

The results revealed that subjects who were doing unsupported diets had significantly increased stress levels which was linked strongly to severely impaired task performance. Control participants and the women attending weight loss groups gave identical results in both cases, displaying lowered stress levels, and increased efficiency when performing the computer task.

‘Given that some weight loss strategies are more successful than others, and that some types of diet cause increased depression, low self esteem and impairments in mental performance, it’s obviously very important to try and find weight loss strategies that avoid these negative consequences,’ said Dr Mike Green.

‘The kinds of deficits found in mental function from some diets are similar to clinical depression and anxiety disorders. Therefore it is inevitable that these weight loss plans are the most likely to fail. Organised dieting groups are less stressful due to the group support, regulation and nutritional information that they provide, and thus are more effective,’ he concluded.

The news comes at a time when the government is being pushed to establish a strategy to tackle the current obesity epidemic in the United Kingdom. 2002 reports show that over 65% of the UK’s population is overweight with over half a million pounds of NHS money being spent on the cause each year. Health secretary, John Reid, is preparing for an obesity summit in April to address the problem while a report on public health, delegated by the Treasury, is to be published at a similar time.