Low-fat diets may not lead to greater weight loss in the long term when compared to higher-fat diets of similar intensity, according to a study published Oct. 29 in The Lancet Diabetes & Endocrinology.

Researchers conducted a systematic review and random effects meta-analysis of randomized control trials comparing the long-term effect of low-fat and higher-fat dietary interventions, as well as no alteration in diet, on weight loss. The study looked at data from more than 68,000 adults, and found that low-fat dietary interventions do not lead to more significant weight loss than similarly intense low-carbohydrate and other higher-fat dietary interventions, regardless of the weight loss intention of the trial.

Further, in the setting of weight loss trials, higher-fat, low-carbohydrate dietary interventions led to a slight but significant, greater long-term weight loss than low-fat interventions, comparatively. Other higher-fat diets led to similar weight loss when compared to individuals adapting low-fat diets, whether or not the trial had a weight loss goal. Low-fat interventions were only favoured in comparison to interventions of lesser intensity, particularly those in which controls were simply asked to maintain their routine diet.

“There is no good evidence for recommending low-fat diets,” says lead author Deirdre Tobias, MD, from Brigham and Women’s Hospital and Harvard Medical School. “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.”

Moving forward, Tobias called for an increase in available information, saying, “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.”

Keywords: Body Weight, Diabetes Mellitus, Diet, Fat-Restricted, Dietary Carbohydrates, Dietary Fats, Energy Intake, Obesity, Weight Loss

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