A study in the June 3rd issue of the British Medical Journal, compared several commercial weight loss diets at six months and 12 months. There is a wide range of choice in commercial diets but there has been little data comparing how effective they are.

The authors noted that most adults in developed countries dieted some time. Long term success with diets is generally poor with half the weight loss being regained within one year.

This study compared diets such as Slim-Fast Plan which is a meal replacement approach, Weight Watchers Pure Points program which is an energy controlled diet with weekly meetings, Dr Atkins New Diet Revolution which is a low carbohydrate diet and another diet called Rosemary Conely’s Eat Yourself Slim diet and fitness plan which is a low fat diet and weekly exercise class. They looked at changes in weight and body fat during six months.

They found that all diets were associated with significant loss of body fat during six months but that there was no significant difference between the different diet groups. The analysis showed that the average weight loss was about 6kg. Interestingly the Atkins diet did give a significantly higher weight loss in the first four weeks but was no more effective than other diets by the end of the study.

At one year follow up, only 45% were still continuing with their diet.

More participants in the programs without support such as Atkins withdrew than in the supported programs.

Weight rebound after the first six months was higher in the unsupported programs.

Overall though, clinically beneficial weight loss of around 10% after one year was noted in those who had kept to the original diet.

Comments:
It would seem that supported diets, if they are maintained long term, will have significant benefits to those participating. Clearly the challenge is keeping people interested and motivated to continue. Quality Occupational Health will publish more on healthy eating and weight control in the future.

More information on weight loss and what works:
Obesity and Weight loss - what the evidence tells us