People staying in regions with hot and humid climate are more prone to obesity, a study by the University of Texas at Austin suggests. They reason physical inactivity due to hot weather increases the risk.

Researchers said that certain American counties have extreme summers coupled with humidity and rains. People living in these counties have high risk of obesity. Similar logic can be applied for the places with extreme winter. The team said counties with cold, cloudy and dark climate are less likely to go out and exercise. This results in weight gain.

According to the study map, people in the Southeast counties are highly inactive. And these areas have high rates of obesity. Counties in the mountainous West have cool and dry summers making people more active, thus, leading to less obese people in these regions.

"Living in Texas as I do, the results really resonated for me," Paul von Hippel, an assistant professor at the LBJ School of Public Affairs, said in a press release. He co-wrote the study with doctoral student Rebecca Benson.

Researchers advise people to chalk out plans for exercise. They suggest early morning jogs or swim or some indoor game of basketball or skating.

Developers and planners should consider physical fitness when planning environments in such places. "Some planners are more thoughtful about that than others," he said. "A great example of thoughtful planning is the hike-and-bike trail along Lady Bird Lake in Austin, Texas. It's shady, it's next to water and it attracts thousands of walkers, runners and bikers on the hottest summer days."

Researchers said apart from the extreme climate, other factors that influence obesity are demographics, parks, stores and restaurants. However, summers with rain or humidity have a significant impact on obesity rates.

"In a sense, the importance of weather is obvious, but we looked at some other 'obvious' things, and they didn't pan out," von Hippel said. "For example, going in we knew that Coloradans were exceptionally thin and active, so we expected to find that hills and mountains encourage physical activity. But it turns out that terrain matters very little for activity or obesity. In some mountainous areas, like Colorado, people are very active, but in others, such as West Virginia, they aren't."

The study was published in the American Journal of Public Health.