Walking 15 Minutes a
Day Won't Prevent Obesity

Walking briskly for 15 minutes each day is not sufficient to burn off the extra calories in the diet, new research reports.

Rather, to prevent the added pounds from piling up, people need walk briskly for an average of 30 minutes, or 60 minutes if they prefer a slower pace, the authors note.

According to Drs. Alfredo Morabia and Michael C. Costanza of Geneva University Hospital in Switzerland, in most countries, the amount of weight people are gaining is equivalent to taking in an average of 100 extra calories each day.

To determine what level of exercise is needed to burn off those added calories, the authors reviewed information about physical activity collected from 3,014 male and 2,996 female residents of Geneva between 1997 and 2001. The researchers noted how much people exercised, and estimated how many extra calories they would lose if they all walked briskly for 15 minutes each day.

As part of the experiment, Morabia and Costanza assumed that people who already walked 15 minutes each day would continue to do so, and people who typically walked less would increase their activity to no more than 15 minutes of walking per day.

Reporting in the American Journal of Public Health, the researchers found that if every single adult walked briskly for 15 minutes each day, the total amount of extra energy expended each day would average out to significantly less than the extra amount each average person eats.

However, if every adult extended their physical activity to 30 minutes of brisk walking, each person would burn off more than enough to compensate for the extra 100 calories they are eating.

If people prefer a slower pace when exercising, they would need to walk for 60 minutes each day in order to burn off more than 100 calories, the authors note.

"Fifteen minutes per day of moderate or brisk walking, or 30 minutes per day of slow walking, could increase physical activity at the population level," Morabia and Costanza write.

The authors note that they are currently using these results to encourage long, brisk walks in their community, and plan to follow the results to test their predictions about the exercise needed to prevent obesity.

SOURCE: American Journal of Public Health, March 2004.