For weight loss, some swear by "grazing" -- eating several small meals throughout the day -- instead of eating fewer meals at more traditional mealtimes.
Women who ate five meals on one test day and two regular meals on another (consuming the same total calories each day) burned the same amount of calories both days, researchers found.
Despite folklore that grazing somehow revs up your metabolism, it doesn't appear to be the case, said study researcher Dr. Milan Kumar Piya.
"If you eat two meals or five, as long as it's the same number of calories; there is no difference in energy expenditures, so there is no effect on weight loss," said Piya, a clinical lecturer with the U.K. National Institute for Health Research, at University Hospital Coventry and University of Warwick.
He presented the findings Tuesday at a Society for Endocrinology meeting in Liverpool, England.
Those hoping to lose weight can choose the approach they prefer, Piya said. Based on the new findings, he said he would now tell patients trying to lose weight: "You have your own ways of eating and doing things. As long as you eat fewer calories [to lose weight], you will be fine."
He compared the approaches in 24 women, including some who were normal weight and some who were obese. The lean women, on average, were age 34, while the obese women, on average, were 42.
The women were given either two meals or five meals on two separate days, and the researchers measured calories burned, comparing each woman's own individual daily results. Both obese and lean women burned virtually the identical number of calories over a 24-hour period, regardless of which day was analyzed.
Piya also took blood samples twice during each 24-hour period to evaluate signs of inflammation, known as "endotoxins," among other measures. "Obese people have more inflammation to begin with," he noted.
Inflammation, in turn, has been linked in previous studies with a higher risk of developing type 2 diabetes and heart disease.
"At bedtime, when we compared the obese women with the lean women, the obese women had higher endotoxins after the five-meal day," Piya said. That would, he said, theoretically, boost their risk of diabetes and heart disease. "The lean women did not have higher endotoxins when they had five meals compared to two."
The new findings make sense to Michelle Kulovitz Alencar, an assistant professor of kinesiology at California State University, San Bernardino. "In my own research, I have found that it's all about calorie intake," she said, not how the calories are spread out during the day, for weight loss results.
In studies Alencar has done comparing different meal frequencies, she finds those who eat more meals tend to underreport what they actually eat.
Recently, she reviewed published studies on how meal frequency might affect weight loss. That report is published in the April issue of the journal Nutrition.
Researchers remain uncertain about the best meal frequency for weight loss, Alencar said. However, some research suggests fewer meals per day may help obese people control cholesterol better, she noted.
Alencar agreed with Piya, however, that for now people should stick with the approach they are used to. She suspects that those who switch their patterns -- going from three meals a day to five, or the reverse -- may ''throw off'' their hunger hormones, making them feel hungrier in some cases.
For now, Alencar said: "Stick with what you know and reduce calories."
Piya can't say if the findings apply to men. "There are no obvious reasons that we would expect men to respond differently, but obviously we are unable to draw conclusions about men until we [do] studies in men," he said.
Because the new study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
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