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Independents' Day

No 'best diet' for weight loss

Eating less and healthily results in weight loss and a reduction in cardiovascular risk factors irrespective of the type of diet, a study has demonstrated.

More than 800 overweight adults were randomised to one of four diets of different energy composition. The proportion of energy derived from the fat, protein and carbohydrate component of the diets was 20/15/65%, 20/25/55%, 40/15/45% and 40/25/35% respectively. The diets consisted of similar foods and met guidelines for cardiovascular health. Furthermore, study participants were offered group and individual dietary educational sessions for two years. The primary outcome was the change in body weight after two years.

The results showed that at six months participants in each group had lost an average of 6kg (7% of their initial weight). However they began to regain weight after 12 months. At two years there was no significant difference in weight loss across the various groups: 3.0kg in the 15% protein group and 3.6 kg in the 25% group, 3.3kg in both the 20% and 40% fat groups and 2.9kg in the 65% carbohydrate group and 3.4 kg in the 35% group (all P>0.20).

At the completion of the trial the average weight loss was 4kg and 15% of participants had lost at least 10% of their body weight.

Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets.

Attending the education sessions was strongly associated with weight loss with 0.2 kg lost per session.

All the diets reduced risk factors for diabetes and cardiovascular disease at six months and two years. At two years the low-fat diets and the highest carbohydrate diet reduced LDL cholesterol to a greater degree than the high-fat and low-carbohydrate diets. The lowest carbohydrate diet improved HDL-cholesterol more than the highest carbohydrate diet and all diets slightly improved BP and fasting insulin levels with the exception of the highest carbohydrate diet in the case of insulin.

This study has elegantly demonstrated that reducing calorie intake can result in important weight loss, irrespective of the protein, fat and carbohydrate content of the diet.

This should provide further evidence against the fluctuating trend for fad diets.

Sacks FM, Bray GA, Carey VJ et al Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med 2009; 360: 859-73


Dr Peter Savill
GPwSI Cardiology

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