The study, published on Wednesday in the BMJ journal, concerned 164 people with overweight or obesity. Their weight decreased by 12%, and then they were stabilized on this weight and a high, medium or low carbohydrate diet was introduced for 20 weeks.
Diets consisted of 20% carbohydrate and protein and 60% fat, 40% carbohydrate and fat, 20% protein or 60% carbohydrates and 20% protein and fat.
While participants were on these diets, their caloric intake was controlled to maintain their initial weight. If the participant began to lose or gain weight, their caloric intake was increased or decreased.
"If someone accelerated metabolism, he would lose weight, and that would increase the calories just to restore weight to this basic goal," said Ludwig, who is also a professor of pediatrics and nutrition at Harvard University.
Researchers assessed the impact of diet on metabolism, which is one of the things that works against you when you try to keep your weight.
"These findings show that all calories are not metabolism-like and that carbohydrate restriction may be a better strategy than calorie restriction for long-term success," said Ludwig.
He also believes that without the intervention of calorie control, about a low carbohydrate diet it can cause spontaneous weight loss by about 20 pounds in a few years.
Sattar, who was not involved in the study, said the low carb group apparently consumed more calories than other groups to maintain similar weights.
"This shows the second point that what really matters is weight change and we know from longer and larger studies that weight loss is basically similar regardless of the diet used (low carbohydrates or low fat or other) as long as the diet is respected, "he said.
In short, I do not believe that this work changes anything and does not convince me that low-carbohydrate diets are much better for adequate health outcomes. Overwhelming evidence does not support this.
Experts also pointed out that all participants had the same basic metabolic rate, so other non-specific activities could explain differences as well as high levels of saturated fat in a low carbohydrate diet, which can lead to an increased risk of cholesterol and heart disease.