More weight is lost by following low carbohydrate regimes such as the Atkins diet than through the standard low-fat diet recommended by doctors, according to a study.
Over two years, participants on a low-carb diet lost an average of 10.3lbs - compared with 10lbs on a Mediterranean diet and only 6.5lbs on a low-fat diet.
The researchers said these rates were comparable with the results achieved by prescription weight-loss drugs.
Scientists followed the progress of 322 moderately obese workers at the Nuclear Research Centre in Dimona, Israel, who were randomly assigned one of the three diets.
Maximum weight loss was achieved after six months but there were improved health benefits over the whole two-year period.
Lead researcher Dr Iris Shai said: "Clearly, there is not one diet that is ideal for everyone.
"We believe that this study will open clinical medicine to considering low-carb and Mediterranean diets as safe effective alternatives for patients, based on personal preference and the medical goals set for such intervention."
The study, carried out by researchers at Ben-Gurion University of the Negev in Israel, was published in the New England Journal of Medicine.