Writing in the journal Archives of Internal Medicine, the research team, led by Dr Y Aude from Mount Sinai Medical Center in Miami Beach, Florida, says: "For many years the US National Cholesterol Education Program (NCEP) and the American Heart Association have advocated low-calorie and low-fat diets that are high in carbohydrates."

However, because such diets are known to reduce high-density lipoprotein ("good" cholesterol) levels and to increase levels of fats called triglycerides in the blood, therefore raising the risk of heart disease, the NCEP diet has become controversial.

Recently it has been suggested that a reduced calorie, modified low-carbohydrate (MLC) diet, which is lower in total carbohydrates but higher in protein, mono-unsaturated fat and complex carbohydrates, might have a better effect than the NCEP diet on weight and cholesterol levels.

To investigate, the team asked 60 volunteers to follow the NCEP or MLC diet for 12 weeks. All of the participants were overweight, with a body mass index of at least 27.

The researchers found that, over the course of the study, individuals eating the MLC diet lost an average of 13.6 lb, significantly more than the average 7.5 lb lost by those on the NCEP diet.

However, there were no significant changes between the groups for total, low density ("bad cholesterol") and high-density lipoprotein cholesterol and triglyceride levels.

The researchers conclude: "Compared with the NCEP diet, the MLC diet... caused significantly greater weight loss over 12 weeks.

"There were no significant differences between the groups in blood lipid (fats) levels."

However, adding that the study was limited by its short duration and small number of volunteers, the team calls for further trials of sufficient size and duration to confirm or refute the findings.