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Boston Children’s Hospital study may add to case supporting low carb diet

Is bread your friend? New research adds to the case for cutting carbs.
Is bread your friend? New research adds to the case for cutting carbs. (Rimglow - Stock/Adobe)

Is it time to cut the carbs?

New research from Boston Children’s Hospital, in partnership with Framingham State University, may add new weight to arguments for reducing carbohydrates in your diet.

The study of a group of overweight adults who had recently lost weight found that eating fewer carbs increased the number of calories they burned.

The findings, published Wednesday in the British Medical Journal, suggest that low-carb diets can help people keep off the pounds they lose, researchers said.

“Our observations challenge the belief that all calories are the same to the body,” researcher Cara Ebbeling, codirector of the New Balance Foundation Obesity Prevention Center in Boston Children’s Division of Endocrinology, said in a statement.

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She noted that other studies “suggest that low-carb diets also decrease hunger, which could help with weight loss in the long term.”

The study looked at 234 overweight adults who were fed an initial weight-loss diet for about 10 weeks. Of that group, 164 achieved their goal of losing 10 to 14 percent of their body weight and went on to the next phase of the study, which lasted 20 weeks. In that phase, they were separated into high-, moderate-, and low-carb groups.

The researchers found that the number of calories people burned was significantly greater when they were on the low-carb diet rather than the high-carb diet.

The study suggested that a low-carb, high-fat diet “might facilitate weight loss maintenance beyond the conventional focus” on controlling calories and encouraging physical activity.

Dr. David Ludwig, who codirects the obesity prevention center with Ebbeling and worked on the study with her, said it tested the “carbohydrate-insulin model,” a theory that suggests processed carbs, through their effect on insulin, play a key role in causing people to gain weight.

Ludwig, who has been developing the theory with Ebbeling for about 20 years, said in a telephone interview that reducing processed carbs in your diet “will not only help you lose weight, but it will help you keep it off over the longer term.”

The theory — and the value of low-carb diets — have been a subject of some debate. But the researchers said the study’s findings were in line with several key predictions of the theory.

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Ludwig said, “We do feel this is the longest, most rigorous study to date of the question, ‘Are all calories alike to the body?’ And the answer is, ‘No.’”

“This challenges the conventional approach that tells people to just eat less and move more,” he said.

The study was funded by a $12 million grant and, under it, more than 150,000 meals were prepared for participants, who were members of the Framingham State community, aged 18 to 65.

Deirdre Tobias, an associate epidemiologist and assistant professor at Harvard Medical School and Brigham and Women’s Hospital, said the current thinking is that low-carb diets are “moderately more successful” than low-fat diets for weight loss.

The problem, Tobias said, is that people, whatever diet they’ve had success with, have a problem keeping the weight off.

“We know a lot of different diets will get you that weight loss at six months, but when you look 12 months out or further, the weight in many cases has been regained or even surpassed,” she said.

“From a public health point of view, that’s one of the biggest pieces in the weight loss story,” she said.

The Boston Children’s study points to a way for people to maintain their reduced weight, she said. “The evidence from this study indicates that low-carb diet leads to higher energy expenditure, which, in the long run, would help you maintain that weight loss,” she said.

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Ludwig’s bottom line advice? Cut back on processed foods, refined grains, potato products, and sugar. That “will get most people most of the way,” he said.