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Many overweight people who lose excess poundage regain
it. This fact has long been explained by the "setpoint theory"
-- the idea that people have a set weight determined by metabolism that is
difficult change.
"You lose weight," said Roland L. Weinsier,
M.D., director of the clinical nutrition research center at the University
of
Alabama at Birmingham. "You try against high odds to maintain that
weight loss, and it seems almost inexorable that the weight is brought
back, sometimes even higher. And then you repeat
the cycle."
But research presented by Weinsier at the Annual
Clinical
Congress of the American Society for Parenteral and Enteral
Nutrition in January challenged that idea, saying that formerly
overweight people have metabolisms similar to those who have
never been overweight.
The studies suggest that other factors -- environmental
and
physiological -- may play a much larger role.
Researchers like Weinsier hope that disproving the
setpoint
theory will give physicians better tools and greater motivation
to help their overweight patients lose pounds.
"I think it changes our mind-set to take us
physicians away
from thinking of this as out of our control or out of the
control of the patient," said Weinsier. "It is extremely
difficult to lose weight, but we have to change ourselves and
the environment to come up with a better paradigm for treating
obesity."
Weinsier's most recent study was published in the
November 2000
American Journal of Clinical Nutrition. Over a four-year period,
he followed 24 overweight women who dieted, and compared them
with 24 never-obese subjects. The study found that although
resting metabolic rate fell while the women were dieting, it
returned to normal when their food intake also returned to
normal. In the dieting group, 85 percent of the women regained
much of the weight lost. The weight of the women in the control
group remained unchanged.
"It really highlights the importance of changing
the environment,"
said Robert F. Kushner, M.D., president of the American Society
for Parenteral and Enteral Nutrition. "There are some people who
are likely to gain weight faster than others. We don't know
exactly what it is, but the environment has a lot to do with it."
"I can well envision that all of us day to day are
being influenced
by environmental factors that affect regulatory systems that affect
our weight," agreed Weinsier. "I ate breakfast, and I felt
satiated.
But there's something else that's there that just looked appetizing,
and so I took an extra helping. The internal signals are not being
listened to, and there's too much external noise."
Obesity experts said that once metabolism is either
ruled out as
a factor, or its importance minimized, researchers can more closely
scrutinize environmental factors. These factors include the easy
availability of large amounts of food combined with a lack of
opportunity for physical activity. They suspect that these variables
account for much of the skyrocketing rate of obesity in the United
States.
"You take the same person who may be struggling
with controlling
his or her weight to another country, where the environment is
different and conducive to more physical activity and lower energy-
dense food, and they may all of a sudden appear to have outstanding
willpower," said Weinsier.
Doctors who treat obese patients said the information
was valuable
but failed to address the still unexplored gap between the time
when a person is dieting, losing weight and does have a reduced
metabolism, and the time when they return to normal eating but their
metabolism has not yet returned to full steam. It is during this
time that weight regain is most likely.
"The question is really not so much if metabolisms
are the same,
but when they become the same," said Lyn J. Howard, M.D., professor
of medicine at Albany Medical College in New York.
(c) Distributed by Los Angeles Times Syndicate |
