Study: Daily 15-minute walk may not be enough to prevent obesity

Small increases in daily exercise, like a 15-minute walk, are not enough to stave off a population-wide obesity epidemic, according to a new study by Swiss researchers.

Short walks do not burn off enough daily calories to compensate for the yearly weight gain seen in increasingly overweight populations, said Alfredo Morabia, MD, PhD, and Michael Costanza, PhD, of Geneva University Hospitals.

The study appears in the March 2004 issue of the American Journal of Public Health.

Some researchers suggest that people could halt their march toward obesity by cutting 100 calories out of their diets or by exercising to burn this amount each day. But people will have to walk a lot farther than they might think to knock off those 100 calories, Morabia and Costanza said.

"If the specific goal is to approach expending 100 calories a day through walking, the duration should be closer to 60 minutes for slow walking and 30 minutes for moderate or brisk walking," Morabia said.

Using data on the normal physical activity of adults in Geneva between ages 35 and 74, the researchers calculated how many additional calories the city of Geneva as a whole could burn if its citizens added 15- and 30-minute walks to their daily lives.

Even if every adult successfully adopted a 15-minute slow daily walk, the population would burn an average of only nine extra calories a day, Morabia and Costanza found. If all adult citizens participated in a 30-minute slow walk, the average rose to 25 calories per day.

Only brisk 30-minute daily walks taken by all the adults would bring the population's average calorie expenditure to the level of 100 per day, the researchers concluded.

Despite the numbers, Morabia said he still thinks more daily walks could change a population's health for the better.

"The walking habit may grow more rapidly once it has been adopted by a minority -- a snowball effect -- and it may stimulate weight-reducing dietary changes," he said.

This article was prepared by Biotech Week editors from staff and other reports.

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