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
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
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
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.
Reference Source 89