Low-carb, low-fat, keto, Paleo, clean eating, timed eating and on and on. There are so many weight loss strategies to choose from that it can be overwhelming.
Sadly, there doesn't seem to be a taco truck diet or a plan that involves burgers and fries, but there is new research that compared two popular diets: low-carb and low-fat. Scientists at the Stanford University School of Medicine compared to the two approaches and their findings show that neither one is the magic bullet.
The facts showed that either diet would boost weight loss, but neither one is appreciably better than the other. Simply put, cutting carbs and cutting fat are both decent choices to manage weight. The study also looked at what could be called "precision dieting" where a person's genotype or insulin levels could be analyzed to predict which diet would work best. There was no evidence that genotypes or insulin has any predictive value for choosing a diet plan.
Christopher Gardner, Ph.D., professor of medicine and the lead author of the study explained, "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. 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?"
So how did the study work? Over six hundred participants between the ages of 18 and 50 were enrolled with roughly equal numbers of men and women. The volunteers were sorted randomly into two groups: low carb dieters and low-fat dieters. The study period was a full year, however, by the end of the year about 20% of participants had dropped out, due to issues unrelated to the study. Before they began dieting the participants each had genome sequencing and underwent testing for baseline glucose levels. For the first eight weeks, both groups were limited to about 20 grams of fat or carbs. That's the same amount of carbs in roughly one and a half slices of bread, and the fat was the same amount found in a snack of almonds or other nuts. Each group gradually added fat and carbohydrates back into their diets. By the end of the year, the low-fat group averaged about 57 grams of fat per day, and the low-carb dieters averaged about 132 grams of carb-loaded foods. In both groups, this was a reduction in what the participants had been eating previously
Gardner felt the key was that the diets were healthy, regardless of the focus on fat or carbohydrates. He explained, "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. 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 study, the average weight loss for both groups was about 13 pounds. There was no evidence that genotype or insulin levels played any part in predicting success with either of the diets. The team will continue to examine the data; however, for now, the best advice is to eat in a way that is sustainable for your particular lifestyle and choose healthy food, heavy on the vegetables and whole foods and leaving out sugar and processed foods.