George Mason University
George Mason University Mason
George Mason University

When Overeating, Protein Intake is Biggest Factor

July 23, 2018

By Jiaxi Zhang

Obesity is a prevalent public health issue that affects more than one-third of the American population. It has a major impact on health, but it is a challenge to understand how obesity develops and which methods to take in order to reduce it.

A study by Dr. Lilian de Jonge, assistant professor of nutrition and food studies in Mason’s College of Health and Human Services, and her colleagues from the Pennington Biomedical Research Center in Baton Rouge LA, found that overfeeding causes fatty acids to change in the circulation of one’s body, with protein intake being the most important factor affecting changes in metabolism. The study, Plasma fatty acyl-carnitines during 8 weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study, was published in Metabolism earlier this year. In addition, this study also pointed out that, when overfeeding, neither energy intake nor fat intake has much influence on changes in metabolism. Overfeeding is also associated with changes in fatty acids.

“When examining the effects of overeating, overfeeding is one strategy to evaluate the effects of excess of energy intake.  as well as how the different macronutrients can influence the body’s response,” de Jonge stated. “We found that protein intake was the major factor influencing changes in metabolism among those who were overfed. What this means is that, while overeating is unhealthy and leads to a host of health problems, having a high protein diet when overeating may keep metabolism higher and therefore, in the long term, overall weight lower than overeating with different kinds of diets.”

The participants for this secondary analysis were twenty-three healthy men and women between the age of 18 and 35 years with a BMI of 19.7 to 29.6 kg/m2, who did less than 2 hours of moderate to vigorous exercise per week and completed the 8-week overfeeding protocol maintaining both blood sugar levels at baseline. Fatty acyl-carnitines—a marker to determine the likelihood of storing fat in the body – were examined. Individuals were overfed by 40 percent of energy above weight maintenance diets composed of low (5 percent), normal (15 percent), and high (25 percent) of energy by protein. Individuals with high protein diets had lower fatty acyl-carnitines compared to a lower protein diet. The percentage of fat in the diet or energy expenditure did not correlate to fatty acyl-carnitines.

De Jonge noted, “This study had a small sample size, but it clearly showed the importance of how a higher protein diet can influence the storage of fat in the body.” She cautioned, “This research will likely help in a greater understanding of obesity and the factors that contribute to it, but more research to confirm our findings is required.”

Related people: Lilian de Jonge, PhD
Topics: Research
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