A new study didn't find much of a difference between healthy low-fat and low-carb diets.
People on the two diets lost about the same amount of excess weight.
Participants were encouraged not just to go for low-carb or low-fat options but to look for healthy, nutritious replacements.
After the study, participants' attitudes to food had changed for the better.
Dieting is a very personal challenge. A specific eating regimen your friend swears by just may not work for you, and research has shown that there is probably no one-size-fits-all solution for weight loss.
Now, when it comes to the recently popular question of whether cutting carbs or fat is better, new research from the Stanford University School of Medicine has found it may not matter.
The study, published in the Journal of the American Medical Association, followed 609 overweight adults ages 18 to 50, half men and half women, who were put on a healthy low-fat diet or a healthy low-carbohydrate diet for 12 months. About 20% of the participants dropped out because of circumstances.
Results showed that people who cut out carbs or fat while maintaining a healthy diet shaved off about the same proportion of excess weight.
To account for individual differences, the participants did two pre-study activities. They had their genome sequenced so the researchers could look for specific gene patterns that could enhance or inhibit weight loss, and they also received tests for levels of insulin, a hormone produced the pancreas.
Overall, genome and insulin levels didn't affect a person's success on either diet.
"We've all heard stories of a friend who went on one diet — it worked great — and then another friend tried the same diet, and it didn't work at all," Christopher Gardner, a professor of medicine who was the lead author of the study, said in a statement. "It's because we're all very different, and we're just starting to understand the reasons for this diversity. Maybe we shouldn't be asking what's the best diet, but what's the best diet for whom?"
Notably, study participants were encouraged to pursue healthy low-fat and low-carb diets, rather than allowing for diet sodas or foods that aren't particularly nutritious just because they are low in fat or carbs.
"We made sure to tell everybody, regardless of which diet they were on, to go to the farmer's market, and don't buy processed convenience-food crap," Gardner said. "Also, we advised them to diet in a way that didn't make them feel hungry or deprived — otherwise it's hard to maintain the diet in the long run.
"We wanted them to choose a low-fat or low-carb diet plan that they could potentially follow forever, rather than a diet that they'd drop when the study ended."
By the end of the 12 months, participants lost 13 pounds on average. But some people lost more than 60 pounds, while a few gained about 15 or 20. The takeaway, the researchers say, is that going for healthy, nutritious options is the way forward.
"On both sides, we heard from people who had lost the most weight that we had helped them change their relationship to food, and that now they were more thoughtful about how they ate," Gardner said.
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