Protein or carbs? It may not matter!

The Wall Street Journal reported on a study published in the Journal of the American Medical Association suggesting that a person’s total calorie intake, regardless of the nutritional source of the calories, determines how much fat accumulates in the body.

Bloomberg News reports that in the study, 25 healthy participants were “divided into three groups getting a low-protein, high- protein or normal protein diet, with the same calories,” and all were given “an extra 1,000 calories a day.”

Researchers found that participants “getting just five percent of their calories from protein gained significantly less weight than those given more protein, adding 3 kilograms (6.6 pounds), compared with 6 kilograms (13 pounds),” but “low-protein eaters gained just as much fat, and lost lean body mass,” compared to high-protein eaters.

Researchers concluded that “the results suggest the obesity epidemic may be worse than is currently known because those with lower body weight may have undetected layers of fat that can harm their health.”

The Los Angeles Times “Booster Shots” blog explains, “The normal and high protein groups also saw a substantial increase in their resting energy expenditure – how many calories the body burns while at rest.”

This increase in “resting energy expenditure” was not seen for the low protein group.

The Boston Globe “Daily Dose” blog details, “In the low-protein group, the body siphoned off 95 percent of the excess calories to pad the body with more fat, burning off five percent as heat while shedding muscle due to a lack of protein.

In the higher protein groups, the body used 50 percent of the extra calories for fat while burning off 40 percent as heat and depositing 10 percent into new muscle.”

In addition, an accompanying editorial notes, “The study underscores the limitations of relying solely on a bathroom scale to monitor weight over time, especially as the body ages and begins to shed muscle and accumulate fat. … People can be at a healthy weight on the outside with a high percentage of body fat on the inside and that can lead to many health problems.”

Noting an alternative explanation for the weight gain, the ABC News “Medical Unit” blog reports, “Dr. Eric Westman, associate professor of medicine at Duke University School of Medicine in Durham, NC, and co-author of ‘The New Atkins for a New You,’ said the carbohydrate content of the participants’ diets could have caused the gains in fat, not the protein. ‘Carbohydrates were not manipulated in this study, so you can’t say they didn’t contribute to the gains,’ he said.”

According to MedPage Today, a researcher not affiliated with the study explained, “We also know from other research that protein has a higher thermic effect on food. … Higher protein intake requires more calories to digest, absorb, and metabolize compared to carbohydrate or fat. This may partly explain the increased calorie expenditure in the normal-to-high-protein groups.”

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