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Low-fat diets fail to lead to long-term weight loss
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Low-fat diets do not lead to long-term differences in weight change when compared with higher-fat weight-loss interventions, according to research in The Lancet Diabetes & Endocrinology.
In a systematic review and meta-analysis of randomized controlled trials comparing various weight-loss interventions, researchers also found that low-fat diets led to greater weight loss only when compared with no dietary intervention, whereas low-carbohydrate diets led to significantly greater weight loss compared with low-fat regimens.
“There is no good evidence for recommending low-fat diets,” Deirdre K. Tobias, ScD, of the division of preventive medicine at Brigham and Women’s Hospital and Harvard Medical School, said in a press release. “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.”
Tobias and colleagues analyzed data from 68,128 adults participating in 53 studies that compared the long-term effects ( 1 year) of both low-fat and high-fat dietary interventions on weight loss. Trials involving dietary supplements or meal replacement drinks were excluded. Researchers used a random-effects method to estimate the pooled weighted mean difference.
Researchers noted no difference between low-fat and higher-fat dietary interventions when all weight-loss trials were combined (weighted mean difference, 0.36 kg; 95% CI, –0.66 to 1.37), although there was significant between-study heterogeneity. Low-carbohydrate diets led to significantly greater weight loss when compared with low-fat interventions (weighted mean difference, 1.15 kg; 95% CI, 0.52-1.79). When researchers compared low-fat vs. higher-fat diets in non-weight-loss and weight maintenance trials, both diets showed a similar effect on weight loss.
In weight-loss trials, higher-fat diet groups experienced greater weight loss than low-fat diet groups when groups differed by more than 5% of calories obtained from fat.
“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,” Tobias said. “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.” – by Regina Schaffer
Disclosure: One of the study researchers reports receiving royalties for books on nutrition and obesity; another reports receiving research support from the California Walnut Commission and Metagenics.
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