Your mother may have been wrong: skipping meals may be good for
you. It has been known for years that sharply restricting the calorie
intake of laboratory animals increases their life span. But a new study
by researchers from the National Institute on Aging found that mice that
fasted every other day, then were allowed to eat what they wanted on the
intervening days, seemed more resistant to diabetes than did control mice
or animals on calorie-restricted diets. They were also resistant to a
condition similar to Alzheimer's disease.
Intermittent fasting is a much more palatable lifestyle than the
continual self-denial of a highly calorie-restricted diet, says Judith S.
Stern, Sc.D., vice president of the American Obesity Association. "You
can almost have your cake and eat it too."
Study author Mark Mattson, Ph.D., hypothesizes that intermittent
fasting works because each fast is a mild stress. The animals respond by
increasing production of substances known as stress-resistance proteins,
which may make them more resistant to disease. In addition, the
intermittently fasting mice produce more of a chemical called
brain-derived neurotrophic factor (BDNF), which promotes learning, memory
and the growth and survival of nerve cells. This BDNF appears to make the
animals more resistant to a neurotoxin that produces brain damage similar
to Alzheimer's disease, Mattson says.
The intermittently fasting animals' cells also become more adept at
scavenging glucose from blood. That, says Mattson, is an antidiabetic
effect, detectable on glucose tolerance tests.
Stern cautions that it will be years before researchers puzzle out
what this means for humans. In the interim, healthy adults who decide to
fast might not be at great risk, she says, but it may be difficult to
achieve balanced nutrition or to avoid pigging out excessively on the
feast days. Children should not be put on such a diet, she says. And she
notes that some medications probably would not work properly under such a
regimen. "If you have any chronic illness and decide to do this, you
really ought to be in communication with your doctor."