Gram per gram, fat has more calories than carbs or protein, so some people think that cutting back on fatty foods is a good way to eat fewer calories and lose weight. But fat helps us feel full, and consuming less of it often means eating more carbs or sugar. To see if going low-fat really helps, researchers from Brigham and Women's Hospital and the Harvard T.H. Chan School of Public Health compared the long-term effects of low-fat diets versus higher-fat ones. They were surprised to learn just how ineffective a low-fat diet can be.
For a meta-analysis published in the journal The Lancet Diabetes & Endocrinology, they reviewed 53 randomized controlled trials that lasted longer than one year, resulting in a pool of more than 68,000 participants. They found that people on low-fat diets did lose weight, but that approach was no more successful than other, higher-fat diets at helping people shed pounds or keep them off after one year. For instance, those who followed a low-carb plan weighed 2.5 pounds less than fat shunners after a year. But overall, the average weight loss for anyone on a diet intervention was just six pounds.
That number didn't impress lead author Deirdre Tobias since most of the participants were overweight or obese to begin with. For her part, she thinks that focusing on specific nutrients is a trap. "We need to look beyond the ratios of calories from fat, carbs, and protein to a discussion of healthy eating patterns, whole foods, and portion sizes," she said in a release. That is, try to eat less packaged food and don't overeat or skip meals.
Tobias and other experts agree that the best "diet" is an eating plan that you'll actually stick to for the long haul. As Kristin Kirkpatrick, manager of nutrition services at the Cleveland Clinic’s wellness institute, told Bloomberg: "Most people can’t stay on Atkins long-term, and most people can’t stay on an excessively low-fat diet for the long term either. For me and a lot of my friends who are dietitians, you need to adopt a diet where you’re not thinking of these things so intensely all day." Buy the full-fat yogurt and try to stop obsessing so much about your food.