Trials published up to now on the comparison between low-carbohydrate and low-fat diet have considered short-term results, so now, in the USA, the results from a 2-year trial are published, where 307 obese adults (average BMI 36 kg/ m2) have been randomized to a low-carbohydrate diet with no fat restriction or to a low-fat diet (about 30% of calories derived from fats). All participants have received some behavioural instructions, both for weight self-control and for physical exercise. Diabetics and patients with lipid metabolism alterations have been excluded from the trial. With both types of diet, weight loss has been of about 11 kg after one year and of 7 further kg after two years. There has been no difference, in the end, in the levels of triglycerides, of LDL cholesterol, of total cholesterol/HDL cholesterol relation. The levels of HDL cholesterol, instead, resulted higher in the group fed with the low-carbohydrate diet (about 2 mg/dl more). The continuous compliance with the diet has been of about 50% after two years.
Apart from the question whether it is better to reduce carbohydrates or fats to lose weight, the important datum of this trial is that 50% of participants has discontinued diet within 2 years, and this explains very much on the difficulty to lose weight.
