Obese women should slow down to lose weight: study

By Charnicia E. Huggins

NEW YORK (Reuters Health) – Obese women might better manage
their weight by slowing their walking speeds, according to two
Colorado researchers.

“Walking slower for a given distance can burn more calories
that walking at a normal pace,” study co-author Raymond C.
Browning, of the University of Colorado in Boulder, told
Reuters Health. “This may also reduce the risk of
musculoskeletal injury,” he added.

Although the amount of energy used while walking depends on
the speed of the walker, researchers had not previously
determined the amount of energy obese adults used as they
walked at different speeds.

Walking speeds are greatly influenced by the amount of
energy required. Normal-weight individuals typically walk about
1.4 meters per second, or 3 miles per hour, the speed that
requires the least amount of energy. Studies of obese adults,
however, suggest they prefer to walk more slowly than
normal-weight adults. Yet they have also been shown to burn up
to 33 percent more calories while walking.

Thus, it was not known whether the preferred walking speeds
of obese adults also corresponded to the speed that required
the least amount of energy.

To investigate, Browning, a doctoral student in integrative
physiology, and Dr. Rodger Kram, an associate professor in the
department, studied 20 women, half of whom were moderately
obese. They measured the women’s preferred walking speeds as
well as the amount of energy they used to walk a set distance.

The researchers had thought that the obese women would
prefer to walk at slower speeds than their normal-weight peers,
but they did not find this to be true. The obese women walked
slightly less fast, but the difference was not statistically
significant, the team reports in the journal Obesity Research.

Preferred walking speed for women in both groups was about
1.4 meters per second, as indicated in previous research. Also,
the obese women did burn much more calories while walking than
did the normal-weight women

Browning and Kram had expected the obese women to use more
energy due to their heavier mass. Their wider stance and wider
leg swings to the side as they walked would suggest the obese
women burn more calories per minute than their peers.

Still, the difference in calorie consumption between the
two groups was only 11 percent, much lower than expected, the
researchers note.

“Our findings suggest that the walking movement is not as
expensive for obese women as we thought it would be and that
obese individuals are probably adjusting their gait to conserve
energy,” Browning noted.

“We thought that the obese women would walk more slowly
than the normal weight to reduce the effort, but instead they
appear to choose a walking speed that minimizes how much energy
they need to expend to walk a given distance,” Browning noted.

Thus, while both groups burned a similar amount of calories
while walking at their preferred speeds, the obese women used
more effort — i.e., they consumed more oxygen.

In order to burn calories while using the same amount of
aerobic effort used by normal-weight women at their preferred
walking speeds, obese women should reduce their speed to 1.0
meter per second, according to Browning and Kram.

“Our results suggest that walking slower for a set distance
may be an appropriate exercise recommendation for a weight
management prescription in obese adults,” they write.

Due to the reduced health benefits of slower, less aerobic
walking speeds, however, Browning suggests that “non-weight
bearing activities be prescribed to reduce the risk of
cardiovascular diseases.”

SOURCE: Obesity Research, May 5, 2005.