New York, November 24, 2008 - Higher-protein meals may help overweight and obese people burn more fat, the results of a small study suggest.
Research has shown that overweight people are less efficient at burning fat after a meal than thinner people are. In the new study, Australian researchers looked at whether the protein composition of a meal affects that weight-related gap.
They found that overweight men and women burned more post-meal fat when they ate a high-protein breakfast and lunch than when they had lower-protein meals. That is, the added protein seemed to modify the fat-burning deficit seen in heavy individuals.
"Our research suggests that people with higher body fat burn fat better after a high-protein meal than people with lower levels of body fat," lead researcher Dr. Marijka Batterham, of the University of Wollongong in New South Wales told Reuters Health.
A number of studies have suggested that high-protein diets may help people shed weight more easily -- possibly, in part, because protein suppresses appetite better than fat or carbohydrates do.
The current study did not look at weight loss, so it's not possible to tell whether the increased fat-burning seen in overweight participants would translate into fewer pounds over time, Batterham said.
But answering that question, she said, will be the next step.
The findings, published in the journal Nutrition & Dietetics, are based on 18 adults whose post-meal metabolism was tested on 3 separate days. The average age was 40 years, eight subjects were overweight, six subjects had a normal weight, and four were obese.
On day one, they were given a "control" breakfast and lunch composed of 58 percent carbohydrates and 14 percent protein. On the other 2 days, their meals were more balanced, with about one third of calories coming from protein and another third from carbohydrates.
In the 8 hours after the control meal, the investigators found that overweight and obese participants burned less fat than their thinner counterparts did. But that gap was closed when participants ate the higher-protein meals.
The protein-rich meals contained low-fat dairy, lean meat and eggs, along with bread and vegetables as carbohydrate sources. Batterham said she and her colleagues are now testing whether vegetarian sources of protein have similar effects on overweight adults' fat metabolism.
In general, experts recommend that people looking to bulk up the protein in their diets choose their sources carefully -- eschewing bacon and butter in favor of foods like fish, poultry, low-fat dairy, beans and nuts.