'No good evidence’ to support low-fat diets, researchers find

Low-fat diets have been dismissed by a new study, which claims higher-fat eating plans, such as low-carbohydrate or Mediterranean diets, actually lead to greater weight loss.

The report, published in the Lancet Diabetes and Endocrinology journal, analysed 53 long-term studies carried out since 1960, which compared the diets of more than 68,000 people and found traditional advice to cut fat out of one's diet to lose weight is wrong.

In weight-loss trials, researchers discovered low-carbohydrate diets led to greater weight loss than low-fat interventions.

The only time low-fat diets did result in greater weight loss was when they were compared to a usual diet.

“There is no good evidence for recommending low-fat diets,” said Dr Deirdre Tobias, from Brigham and Women’s Hospital and Harvard Medical School in Boston who led the study.

“Behind current dietary advice to cut out the fat, which contains more than twice the calories per gram of carbohydrates and protein, the thinking is that simply reducing fat intake will naturally lead to weight loss. But our robust evidence clearly suggests otherwise.

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

The research, funded by the National Institutes of Health and American Diabetes Association, found that although high-fat, low-carb diets, such as the Atkins, were superior to low-fat diets, no diet worked effectively in the long-term.

Diets tended to give sustained weight-loss for a period of around six-months, according to research, but after this many people stop losing weight and may even recover it once they stop dieting.

In trials, those on low-carb diets only lost 2.2lbs more, on average, than those on low-fat diets.

Dr Tobias said: “To effectively address the obesity epidemic, we will need more research to identify better approaches for long-term weight loss and weight maintenance, including the need to look beyond differences in macronutrient composition - the proportion of calories that come from fat, carbohydrate, and protein.

"Long-term adherence is critical for the success of any dietary intervention, and one should also take into account other long-term health effects of their dietary choices."

Earlier this month, a further study accentuated the benefits of a Mediterranean-style diet, claiming it could slow the ageing process in the brain by up to five years.

While not conclusive, research by neuropsychologists at New York University suggested eating plenty of vegetables, fish, pulses and olive oil - and laying off the red meat and dairy products - keeps the brain youthful.