New evidence from a study may displease those who have opted for the low-fat versus low-carb diet. Neither option is superior:Cutting back on carbohydrates or fats reduces excess weight in about the same proportion, the study said. In addition, the study asked whether insulin levels or a specific genotype pattern could predict an individual's success on both types of diet. The answer was no in both cases.
"We've all heard stories about 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 the study's lead author. “It's because we're all very different, and we're just beginning to understand the reasons for this diversity. Maybe we shouldn't ask what the best diet is, but what is the best diet for whom?”
The study involved 609 participants between the ages of 18 and 50. About half were men and the other half were women. All were divided into one of two food groups:low-carb or low-fat. Each group was instructed to maintain their diet for a year. Individuals participated in two pre-study activities, the results of which were later tested as predictors of weight loss. In the first eight weeks of the study, participants were told to limit their daily carbohydrate or fat intake to just 20 grams, which is roughly equivalent to a 1.5 slice of whole wheat bread or a generous handful of nuts. After the second month, the groups were instructed to make small adjustments incrementally, gradually adding 5-15 grams of fat or carbohydrates, with the goal of achieving a balance they could maintain for the rest of their lives. At the end of the 12 months, people on a low-fat diet reported a daily average fat intake of 57 grams; those of low-carb have about 132 grams of carbohydrates per day.
What's important is that these were healthy low-fat and low-carb diets:a soda may be low-fat, but it's definitely not healthy. Lard may be low carb, but an avocado would be healthier. “We made sure to tell everyone, regardless of the diet they were on, to go to the farmers market and not buy processed foods. We also advised them to diet in a way that didn't make them feel hungry or that we'd deprived them of something — otherwise it's difficult to maintain the diet in the long run," the researcher said. “We wanted them to choose a low-fat or low-carb diet plan that they could potentially follow forever, rather than one that they would drop when the study ended.”
By the end of the study, individuals in the two groups had lost an average of 13 pounds. However, there was still tremendous weight loss variability among them; some lost 60 pounds, while others lost nearly 15 or 20 pounds. But, contrary to the study hypotheses, there were no associations between the genotype pattern or baseline insulin levels and a propensity to succeed in either diet.
Perhaps the most important thing we can learn from this study is that the basic weight loss strategy is similar to a low-fat or low-carb approach. Eat less sugar, less refined flour and as many vegetables as possible. Go for fresh food, whether that's a salad or grass-fed beef.
