Reason for Rebound Weight
Gain Found
Insulin resistance one of the culprits for
weight gain after loosing weight.
Plasma levels of norepinephrine, insulin,
and leptin can help to predict which patients
will rebound after a successful weight loss
program, a new study suggests.
Patients with hypertension also appear to be
at risk of rebound weight gain, said Kazuko
Masuo, MD, PhD, from the Department of
Geriatrics at Osaka University Graduate School
of Medicine in Suita City, Japan. She reported
the results last month at the American Heart
Association (AHA) Scientific Sessions.
"The idea that a simple blood test can
identify those that will yo-yo — before they
even start their diet — is a new
concept," said Robert H. Eckel, MD, chair
of the AHA's Nutrition, Physical Activity and
Metabolism Council and professor of medicine at
the University of Colorado Health Sciences
Center in Denver. "Identification of these
people will help us to help them
long-term."
About two thirds of American adults are
overweight or obese, according to the most
recent government statistics. But it's not for
lack of trying: Experts estimate that up to two
thirds of women and half of men are on a diet at
any given time.
"Part of the problem is that so many of
these people are repeat dieters," said Dr.
Eckel, who moderated a discussion of the new
findings. Studies suggest that as many as two in
three dieters are back on the merry-go-round
within a year, he said.
It is important to note, Dr. Masuo said, that
the rebound rate is high even if dieters adhere
to their weight loss regimens.
In the study, the researchers followed 52
obese young men with normal blood pressure and
61 obese men with hypertension who were on a
low-calorie diet. As part of their weight loss
regimen, all the participants exercised for an
hour each day.
At baseline, mean body mass index (BMI) of
patients was 27.9 kg/m2 in the obese
normotensive group and 28.1 kg/m2 in
the obese hypertensive group. Blood pressure was
an average of 131/83 mm Hg in the obese
normotensive group and 171/106 mm Hg in the
obese hypertensive group.
At six months, about two thirds of the men in
both groups had successfully lost at least 10%
of their body weight.
But by two years later, only 51% of the
successful dieters with high blood pressure had
kept the weight off compared with 70% of those
with normal blood pressure, Dr. Masuo reported.
When both groups of patients were analyzed
together, those who rebounded tended to have
higher blood pressure at baseline: 146/99 mm Hg
compared with 136/89 mm Hg for those who did not
rebound (P < .05), the study showed.
Rebound was defined as more than a 10% increase
in BMI at 24 months compared with BMI at six
months.
Baseline plasma norepinephrine levels were
302 pg/mL in the patients who rebounded compared
with 240 pg/mL in those who did not (P
< .05), the study showed.
Those who rebounded — regardless of blood
pressure — also tended to have higher levels
of plasma insulin at the beginning of the study:
10.8 µU/mL vs. 7.1 µU/mL for the successful
long-term dieters (P < .05).
Also, baseline plasma leptin levels were 19.5
ng/mL in the group that rebounded compared with
28.2 ng/mL in those who did not (P <
.01), Dr. Masuo said.
The results suggest that sympathetic
overactivity and insulin resistance contribute
to rebound after weight loss, she said.
"If we could find how to improve the
sympathetic nervous sensitivity of [receptors
that mediate thermogenesis and weight loss
during sympathetic activity], this would be
beneficial in obesity and obesity-related
hypertension," Dr. Masuo said. AHA 2003
Scientific Sessions: Abstract 3049.
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