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(Reuters Health) – For years, dieters have been told that a calorie was a calorie, but a new study suggests that people can burn more calories with a low carb diet than they do. with a diet rich in carbohydrates.
"These results showed that not all calories are the same for the body," said co-author of the study, Dr. David Ludwig, co-director of the New Brunswick Obesity Prevention Center. Balance Foundation at Boston Children's Hospital. "Limiting carbohydrates could be a better strategy than limiting calories in the long run."
The new study was not about losing excess pounds, but rather about a factor that makes it difficult to maintain weight loss: the fact that the body adapts to pounds lost due to a lack of weight. slowing metabolism, resulting in a reduction in the number of calories burned. And for most, it means that the weight is taken up.
Ludwig subscribes to a theory, known as the carbohydrate-insulin model, which suggests that increasing the consumption of so-called high-glycemic foods – which greatly increase blood sugar levels right after their consumption – trigger hormonal changes that increase hunger and lead to weight gain.
To see if the type of food people eat changes metabolism and hunger, Ludwig and his colleagues recruited 164 overweight adults aged 18 to 65 who had already lost 10% of their body weight and randomly assigned them at one of three variable carbohydrates. diets for 20 weeks.
The volunteers' meals, provided by the researchers, had the same number of calories per day and all contained 20% protein. However, one group's diet included 20% fat and 60% carbohydrate, another group had a 40% fat and 40% carbohydrate diet, and the third group consumed 60% fat and 20% fat. carbohydrates.
After tracking the volunteers' weight and measuring energy expenditure throughout the study period, it was clear that those who had consumed the least carbohydrate burned the most calories. Perhaps equally important, their hormone levels regulating hunger, ghrelin and leptin, were also lower.
Volunteers in the low-carb group burned 209 to 278 calories more per day than those on a high-carbohydrate diet, which meant that they burned 50 to 70 more calories per day for every 10 percent reduction. % of carbohydrates their total energy intake, according to the report. report in the BMJ.
The volunteers with the highest insulin secretion at the start of the study had an even more dramatic difference in energy expenditure: those on a low carbohydrate diet burned 478 more calories per day than those who consumed the most. carbohydrates.
This type of extra calorie burn would result in "about 20 pounds of weight loss in a year in those who follow a low carbohydrate diet compared to those in the high carbohydrate group," Ludwig said.
The new study is "exciting and unique," said Dr. Rekha Kumar, a specialist in endocrinology and obesity medicine at NewYork-Presbyterian and Weill Cornell Medicine in New York. "Most studies seek to induce weight loss," Kumar said. "This one is about weight maintenance. And the question is: is there a particular composition of macro-nutrients that can cause a higher calorie burn? "
The fact that people with higher insulin levels "had the greatest impact allows us to say that this is quite valid," said Kumar, who did not participate in the event. 39; study. "It's because these are the people – the ones who have blood sugar and insulin problems – that you can expect."
The results provide hope that changing nutrients in the diet can affect energy expenditure, said Lisa Martich, specialist dietician at the Magee-Womens Hospital of the Medical Center. University of Pittsburgh.
And this could end up being used as "another tool" in weight loss programs, said Martich, who did not participate in the study.
"I think there's a tendency to go all or nothing, just saying eat a low carb diet and that it's going to keep the weight off," Kumar explained. "Maybe a low-carb diet can help, but so does the increase in exercise."
SOURCE: bit.ly/2PFm3i0 The BMJ, online November 14, 2018.
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