[Role of lipid intake in obesity]

It is a commonly accepted fact that the fat in our diet plays an important role in the onset and maintenance of obesity. The excess consumption of energy associated with a high intake of fat and the greater metabolic efficiency in its use are the mechanisms suggested to support the relationship between dietary fat and adiposity. Nonetheless, the epidemiological evidence in favour of lipid intake as a promoter of obesity is not conclusive. Intervention studies, on the other hand, consistently show that there is a modest decrease in weight associated with low fat diets ad libitum, which seems to be explained by the reduction in the intake associated with such an intervention. However, this effect on weight is not maintained over time as considerable reductions in the intake of lipids in the long term seem to have no or minimal effects on corporal adiposity. It has been consistently proven that the restriction of total calories leads to greater weight losses than those achieved exclusively with fat restrictions and, on the other hand, there is very little evidence that low-fat diets per se lead to a weight loss regardless of the calorie restriction. Finally, it must be remembered that low-fat diets rich in carbohydrates are not without undesirable side effects, particularly on cardiovascular risk factors. In conclusion, a change in habits leading to an overall restriction in calories and the promotion of physical activity is a much more desirable strategy in the treatment and prevention of obesity than the apparently promising restriction of lipids in isolation.