Dieting is a very personal challenge. A specific eating regime your friend swears by just might not work for you, and research has shown that there is probably no one-size-fits-all when it comes to weight loss.
New research from Stanford University School of Medicine has found that when it comes to cutting out carbs or fat, neither option is better than the other.
The study, published in the Journal of the American Medical Association, followed 609 overweight adults between the ages of 18 and 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 due to circumstances.
Results showed that people who cut out carbs or fat 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 had their insulin levels tested — a hormone produced the pancreas.
Overall, genome and insulin levels didn't have an impact on an individual'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," said Christopher Gardner, a professor of medicine and the lead author of the study, 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?"
Over the course of the study, participants were encouraged to go for healthy low-fat and low-carb diets, rather than going for diet sodas and 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," said Gardner. "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, individuals had lost an average of 13 pounds. Some people lost a lot more than others, dropping over 60 pounds, while a few gained about 15 or 20. But 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," said Gardner.