PARIS • Low-fat diets do not yield greater weight loss than other slimming regimes, says a study, adding to the long-running debate on how best to shed extra kilos.

A review of 53 scientific studies, covering nearly 70,000 adults in several countries, found "no good evidence for recommending low-fat diets", said lead author Deirdre Tobias of the Brigham and Women's Hospital in Massachusetts in the US.

"The science does not support low-fat diets as the optimal long-term weight-loss strategy."

In fact, low-carbohydrate diets led to greater weight loss than low-fat ones, according to study results published in The Lancet Diabetes & Endocrinology journal on Thursday. In trials that lasted at least a year, weight loss from a low-fat diet came to just 360g, compared with 1.15kg from a higher-fat, low-carb eating plan.

Even so, no approach was a magic bullet. All the dieters in the studies analysed lost just 2.7kg on average in a year. "That's not very clinically meaningful," Dr Tobias said.

Dietary fat has long been targeted in weight-loss plans, says the study, because each gram contains over twice the calories of a gram of carbohydrates or protein.

Over the years, research has yielded contradictory results.

Last month, a study in the journal Cell Metabolism said cutting fat caused obese people to lose more body fat than restricting carbs. But a recent meta-analysis of other studies comparing low-fat diets with others found the contrary.

Dr Tobias said "the thinking is that simply reducing fat intake will naturally lead to weight loss... but our robust evidence clearly suggests otherwise".

She said more research must be done to "identify better approaches for long-term weight loss and weight maintenance".

A comment on the study said it showed weight loss overall was poor, regardless of the diet chosen.

"Long-term diet adherence is abysmal, irrespective of whether low-fat or other diets... are prescribed," wrote Dr Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases in the United States.

Professor Tom Sanders of King's College London said the best diet is to eat less and exercise more.

"To me, the take-home message from this paper is that energy intake determines the extent of weight loss rather than the relative proportions of fat and carbohydrates in the diet," he said through the Science Media Centre.

AGENCE FRANCE-PRESSE, BLOOMBERG