Looking for the Founatain of Youth? Cut your calories, research
suggests
July 03, 2008
Want to slow the signs of aging and live longer? New Saint Louis
University research suggests cutting back on calories could be a
promising strategy.
Calorie restriction has long been shown to slow the aging process in
rats and mice. While scientists do not know how calorie restriction
affects the aging process in rodents, one popular hypothesis is that
it slows aging by decreasing a thyroid hormone, triiodothyronine (T3),
which then slows metabolism and tissue aging.
A new study in the June 2008 issue of Rejuvenation Research, found
that calorie restriction =96 cutting approximately 300 to 500 calories
per day =96 had a similar biological effect in humans and, therefore,
may slow the aging process.
"Over recent years, there has been a huge amount of debate about
whether calorie restriction slows the aging process in humans," said
Edward Weiss, Ph.D., associate professor of nutrition and dietetics at
Saint Louis University's Doisy College of Health Sciences and lead
author of the study.
"Our research provides evidence that calorie restriction does work in
humans like it has been shown to work in animals. The next step is to
determine if this in fact slows age-related tissue deterioration. The
only way to be certain, though, is to do a long-term study."
In the current study, Weiss wanted to know if calorie reduction would
lower T3 levels in humans. To determine if the lowered levels of T3
were a result of calorie restriction and not decreases in fat mass in
general, Weiss also recruited volunteers to lose weight through
exercise.
Study volunteers included sedentary, non-smoking, 50- to 60- year-old
men and post-menopausal women with average or slightly above average
body man index values. They were in otherwise good health and did not
have cardiovascular disease, diabetes, lung disease, uncontrolled
hypertension and evidence of malignancy.
Volunteers were randomly assigned to one of three groups =96 a calorie-
restriction group, an exercise group or a control group =96 and followed
for one year. Volunteers in the calorie restriction group lost weight
by reducing their daily calorie intake by 300 to 500 calories per day.
Volunteers in the exercise group maintained their regular diet and
exercised regularly.
Volunteers in both the calorie-restriction and exercise groups
experienced similar changes of body fat mass. However, only volunteers
in the calorie restriction group also experienced lower levels of the
thyroid hormone.
Although a long-term study is still needed to determine if reducing T3
levels through calorie restriction does indeed slow the aging process,
Weiss says cutting back on calories is a good idea.
"There is plenty of evidence the calorie restriction can reduce your
risks for many common diseases including cancer, diabetes and heart
disease," Weiss said. "And you may live to be substantially older."
When cutting calories, Weiss warns that it is imperative to maintain a
healthy diet by eating nutrient-rich foods. Cutting 300 to 500
calories per day is equivalent to skipping dessert or substituting a
turkey sandwich instead of a Big Mac and fries.
"Anorexia nervosa is a condition that is associated with calorie
restriction that is far too severe and is accompanied by inadequate
intakes of many nutrients. Consequently, it results in premature
disease and even death, rather than improvements in health and a
slowing of aging."
Because it also slows metabolism, Weiss warns that calorie-restricted
weight loss could make people more prone to weight gain over time. On
the other hand, people who lose weight through exercise are not as
likely to gain weight back if they quit exercising. The key to
maintaining a healthy weight, Weiss says, is keeping a consistent diet
and exercising regularly.
Source: Saint Louis University
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