Bring on the avocado.
New research published Thursday found yet again that cutting fat out of a diet is not the most effective way to lose weight, and that in general, a low-fat diet does not have the best results when it comes to keeping weight off over the long term.
Researchers at the Harvard T.H. Chan School of Public Health and Brigham and Women's Hospital did a review of 53 studies that included more than 68,000 participants in an attempt to assess the long-term effects of a low-fat diet versus a higher fat-diet on weight loss over time. Many diet studies last less than a year, making long-term success impossible to judge. For this paper, the researchers looked at past studies that lasted at least a year.
Low-fat diets did not lead to greater weight loss, the researchers report. In addition, higher fat diets that are low in carbohydrates were slightly but significantly more likely to lead to long-term weight loss compared to a low-fat approach. Overall, higher fat diets had similar weight-loss results as low fat, and across all diets, people were only shedding around 6 lbs total.
"The key takeaway here is it’s likely not going to be fats versus carbs when it comes to weight loss," says study author Deirdre Tobias, an epidemiologist at Brigham and Women's Hospital . "We need to think of foods and healthy patterns rather than thinking about individual nutrients." Tobias says trans fats—the worst kind of fat for the heart—should still be avoided.
This can be confusing for people who have been heeding the longstanding adviceto cut out fat. The study authors say other studies and analyses have looked at research that had less than a one-year follow-up, and short duration trials may not be representative of the effects on long-term weight loss.
The researchers conclude that their study, which is published in the journal The Lancet Diabetes & Endocrinology, does not support the efficacy of low-fat diets over higher-fat diets of higher intensity for "meaningful weight control."
They add that public health guidelines should stop recommending low-fat diets for weight loss, stressing that more research is needed to find what strategy is most effective and able to be maintained.