Obesity study tests gender, ethnicity

Obesity expert and School of Health, Physical Education, and Recreation Associate Professor Dong-Chul Seo conducted a study that indicated engaging in the recommended amount of leisure-time physical activity decreased obesity rates in only white women, blurring the lines of the roles gender and ethnicity play in obesity prevention.

“What surprised me is the finding that the dose-response effect of leisure-time physical activity was not clear for men of all races and ethnicities and women of minority race and ethnicity,” Seo said, “especially among Mexican women, whose prevalence of obesity increased as physical activity increased among overachievers.”

Seo said he conducted this research because no prior studies have compared the dose-response relationship of leisure-time physical activity and obesity on a population level.

Seo combined National Health and Nutrition Examination Survey data from 1999 to 2006 to examine this issue by using a large sample of people. The data analyzed a sample of 12,227 adults aged 20 to 64.

“I expected that there would be a dose-response relation between the amount of leisure-time physical activity and obesity rates regardless of gender and race and ethnicity, because the more energy you expend, the less likely you will gain weight,” Seo said.

He added that although relatively little is known about the effect of lifestyle physical activity of the human metabolism on a population level, the findings of this study suggest regular physical activity helps create an energy deficit which, in turn, promotes weight loss among women aged 20 to 64 years in a dose-response manner.

He also said it deserves mention that the biggest decline in the prevalence of obesity between adjacent leisure-time physical activity groups was found between women who engaged in physical activity but fell short of the recommended minimum guideline and women who met the recommended guideline.

National guidelines call for a minimum of 450 to 750 metabolic equivalent, or MET, minutes per week. This is a way of quantifying the total amount of physical activity in a way that is comparable across various forms of physical activity.

Walking briskly for 30 minutes, for example, is about 100 MET. Running 6 mph for 30 minutes is about 300 MET.

“This finding supports the efficacy and efficiency of the current recommended minimum guideline of physical activity at least in terms of weight control, although it was only applicable to women,” Seo said.

Seo said the difference might be because leisure-time physical activity might account for a much smaller proportion of total daily energy output. Another finding of this study illustrates that those who perform heavy work or carry heavy loads might not necessarily create an energy deficit.

Though Seo said he will continue to research this topic further, this study could provide a new insight to the recommended amount of leisure-time physical activity for different ethnicities.

“White women are highly recommended to engage in the recommended level of physical activity,” Seo said. “But men and women of other races and ethnicities are recommended to watch what they eat while engaging in more physical activity.”