EatingWell takes on the case of Calorie Restriction

EatingWell takes on the case of Calorie Restriction

Compelling nutrition trends make headlines daily. But how solid is the science behind them? Why might they matter to you?

The charge: Cutting calories by 25 to 30% could add years to your life.

Testimony: "Calorie restriction isn't about starvation; it's about maximizing nutrients on fewer calories," says Bob Cavanaugh, 58, a landscape contractor in Morehead, North Carolina and member of the Calorie Restriction Society, a nonprofit group that promotes the "CR" lifestyle. Cavanaugh eats 1,800 calories a day-about 75% of what's recommended for a moderately active man his age-mostly from vegetables and whole grains.

Supporting evidence: Research long has shown that CR increases lifespan in animals. Preliminary results of a human trial, published recently in the Journal of the American Medical Association, are encouraging: After six months of 25% calorie restriction (achieved through diet alone or diet plus exercise), 48 overweight adults registered lower levels of DNA damage, which experts believe to be an important factor in the aging process. What's the likely connection? Free radicals, which damage DNA, are a by-product of normal food metabolism, so eating less food results in a lower metabolic rate and, consequently, decreased production of free radicals. (While weight loss initially occurs with CR, continuing to lose weight isn't the goal.)

Expert witness #1: "Calorie restriction is very promising, though it's not easy when food is so abundant," says Eric Ravussin, Ph.D., one of the study's investigators. "But if the full study reveals significant health advantages, I think some people will say, ‘Yeah, I'd like to live 5 or 10 years longer.'"

Expert witness #2: "It's generally healthy and likely to extend lifespan-by 3 to 5% (vs. 50 to 70% in rodents)," says Jay Phelan, Ph.D., a UCLA evolutionary biologist who has studied CR. "After a decade of depriving yourself, you might get a couple of extra years."

OUR verdict: Meeting-not exceeding-your energy needs with nutrient-dense foods is an excellent idea. But even if longer-term studies pan out, restricting calories doesn't guarantee that you will live longer. And think of it this way: does making every calorie count (and removing the joy of eating!) present the possibility of a longer life-or just an extended existence?