April 4, 2006
Eating less may lead to a longer life
By Clementine Wallace
NEW YORK (Reuters Health) - A preliminary study in human
suggests that reducing calories may well extend life,
researchers report in this week's Journal of the American
restriction increases maximum life span in several animal
species. However, there hasn't been any proof of it being the
case in humans," co-author Dr. Eric Ravussin, from Louisiana
State University in Baton Rouge, told Reuters Health. "This is
the first step toward looking at the beneficial effects of
calorie restriction in humans."
Ravussin and his team enrolled 48 healthy overweight (but
not obese) men and women in a 6-month trial looking at the
effects of calorie reduction. Participants were assigned to one
of four groups: a control group, which followed a normal diet;
a calorie restriction group, which received 25 percent less
calories than the daily requirement; a third group, which
exercised and reduced calorie intakes (12.5 percent calorie
restriction and 12.5 percent increase in energy expenditure);
or a group that received a very low calorie diet, starting with
890 kcal a day and then increased to maintain a 15 percent
After 6 months, while patients in the control group lost
about 1 percent of their weight, both calorie restriction
groups (with or without exercise) lost approximately 10
percent. Individuals on the very low-calorie diet lost nearly
14 percent of their weight.
The researchers also observed lower blood levels of insulin
after fasting and a lower body temperature in all participants
who undertook a restricted calorie regimen.
"Body temperature and blood insulin levels are markers of
longevity like gray hair or wrinkles can be, " said Ravussin.
"It has been shown both in animals and humans that those with
lower body temperature tend to live longer, and so do those
with lower fasting insulin levels."
Another important finding, according to Ravussin, was that
less DNA damage seemed to occur in patients with lower calorie
"One of the many theories of aging is that there is more
DNA damage happening, which is the destruction of genetic
information -- smokers for example have more DNA damage," said
Ravussin. "So this is a very important information, totally
novel in humans, that calorie restriction can reduce DNA
SOURCE: JAMA, April 5, 2006.