What makes a diet "calorie-restricted"??

They used to feed us 3K-calorie breakfasts during Army basic training.
Them MREs are supposed to be like 5K calories! I was in the best shape
of my life, despite having accrued problems like a bad back, etc.

How many calories does the body need if you're staying home all day
reading a book or watching one of them holiday season re-run marathons
(Honeymooners, Star Trek, Three's Company, Godzilla)?

How many calories if you go to the gym three times a week
weight-lifting for about an hour each session?

I must say, I'm impressed to learn that the Dalai Lama is, what, close
to seventy? He really looks forty-something!

Also, I wonder what effect sex and the sex drive have on all this...I
feel most alive when having sex, but in between girls I also feel
great, just in a different way...kinda like the strength you feel
before a workout, and the sense of strength you have after it....



http://www.nytimes.com/2006/10/31/he...&ex=1162530000


EXCERPTS

"In mice, calorie restriction doesn't just extend life span,"
said Leonard P. Guarente, professor of biology at the Massachusetts
Institute of Technology. "It mitigates many diseases of aging:
cancer, cardiovascular disease, neurodegenerative disease. The gain is
just enormous."

....

Despite widespread scientific enthusiasm, the evidence that calorie
restriction works in humans is indirect at best. The practice was
popularized in diet books by Dr. Roy Walford, a legendary pathologist
at the University of California, Los Angeles, who spent much of the
last 30 years of his life following a calorie-restricted regimen. He
died of Lou Gehrig's disease in 2004 at 79.

....

Animals on restricted diets seem particularly resistant to
environmental stresses like oxidation and heat, perhaps even radiation.
"It is a very deep, very important function," Dr. Miller said.
Experts theorize that limited access to energy alarms the body, so to
speak, activating a cascade of biochemical signals that tell each cell
to direct energy away from reproductive functions, toward repair and
maintenance. The calorie-restricted organism is stronger, according to
this hypothesis, because individual cells are more efficiently
repairing mutations, using energy, defending themselves and mopping up
harmful byproducts like free radicals.

....

"The stressed cell is really pulling out all the stops" to preserve
itself, said Dr. Cynthia Kenyon, a molecular biologist at the
University of California, San Francisco. "This system could have
evolved as a way of letting animals take a timeout from reproduction
when times are harsh."

....

Despite the initially promising results from studies of primates, some
scientists doubt that calorie restriction can ever work effectively in
humans. A mathematical model published last year by researchers at
University of California, Los Angeles, and University of California,
Irvine, predicted that the maximum life span gain from calorie
restriction for humans would be just 7 percent. A more likely figure,
the authors said, was 2 percent.

....

While an anti-aging pill may be the next big blockbuster, some
ethicists believe that the all-out determination to extend life span is
veined with arrogance. As appointments with death are postponed, says
Dr. Leon R. Kass, former chairman of the President's Council on
Bioethics, human lives may become less engaging, less meaningful, even
less beautiful.

"Mortality makes life matter," Dr. Kass recently wrote.
"Immortality is a kind of oblivion - like death itself."

That man's time on this planet is limited, and rightfully so, is a
cultural belief deeply held by many. But whether an increasing life
span affords greater opportunity to find meaning or distracts from the
pursuit, the prospect has become too great a temptation to ignore -
least of all, for scientists.

"It's a just big waste of talent and wisdom to have people die in
their 60s and 70s," said Dr. Sinclair of Harvard.