Shedding excess pounds is associated
with substantial health benefits, and experts agree
that the fear of regaining lost pounds is no reason
not to lose them in the first place. (See Daily Health
News, July 19, 2004.)
However, while losing weight is a
good idea, repeatedly losing and regaining it places
strain on the body -- including on a woman’s immune
system, as was found in a recent study at Fred Hutchinson
Cancer Research Center in Seattle, Washington.
About the Study
According to Cornelia M. Ulrich,
PhD, senior author and assistant member of the Hutchinson
Center’s Public Health Sciences Division, weight cycling
(the medical term for yo-yo dieting) leads to reduced
activity of natural killer cells, which normally destroy
viruses and also may have a role in fighting cancer.
The more often a woman loses and regains weight, the
lower her natural killer cell function becomes and the
higher the risk of disease.
In the study, researchers interviewed
114 overweight but otherwise healthy women over age 50
and recorded their weight histories for the past 20 years.
Nearly three-quarters of the women had lost more than 10
pounds at least once during that period through dieting.
Next, Dr. Ulrich and her colleagues measured the number
of the women’s natural killer cells via blood tests.
They discovered that..
Women who lost and regained weight most
often -- five or more times during the 20-year period --
had the lowest level of natural killer cells.
Women who maintained the same weight
for five or more years had 40% greater natural killer
cell activity than those whose weight remained stable
for fewer than two years.
Although the study included only
women and further research is needed, Dr. Ulrich
believes that the immune systems of men would most
likely respond to weight cycling in the same way.
Choose a Balanced Approach
Is this a free pass to stay
overweight? Not at all, says Dr. Ulrich. She says
that among those who are obese or overweight,
reduced weight has indisputable health benefits.
Dr. Ulrich recommends a balanced
approach to losing weight. Don’t try fad diet after
fad diet -- that behavior is doomed to failure.
Lifestyle change is the cornerstone of weight control.
The secret to taking pounds off and keeping them off
is to make gradual changes in diet and exercise that
you can live with for the long term. For more on
healthy dieting strategies, see Daily Health News,
January 22, 2004.
Sources...
Cornelia M. Ulrich, PhD, assistant
member of the Public Health Sciences Division, Fred
Hutchinson Cancer Research Center, Seattle,
Washington.
