Trim Calories for Healthier Aging?

May 10, 2006 -- The number of calories you consume could make a difference in your body's aging process.

The key may be trimming calories by a small amount -- perhaps even as little as 8%, according to a study in the journal Antioxidants & Redox Signaling.

If you consume 2,000 calories per day, an 8% cutback shaves 160 calories off your daily calorie budget. That's less than the calories in 2 tablespoons of cooking oil.

The new study was based on rats, not people. The researchers included doctoral student Arnold Seo and Christiaan Leeuwenburgh, PhD. Both are with the University of Florida's Institute on Aging.

Slightly Cutting Calories

Other studies of animals have shown longevity benefits with calorie restriction. Those studies commonly slashed calories by 30% to 40%, note Seo and colleagues.

Cutting calories by 8% seems "more realistic in a human situation," the researchers write. They wanted to see if mild calorie restriction affected the aging process in rats' livers.

Seo and colleagues studied four groups of male rats:

• Young rats (6 months old) with unrestricted calories.
• Old rats (24 months old) with unrestricted calories.
• Old rats raised from a young age on 8% fewer calories than their peers.
• Old rats raised from a young age on 8% fewer calories than their peers and with round-the-clock access to an exercise wheel.

The researchers checked the old rats' livers when the rats were 24 months old. The livers of rats in the calorie-restricted groups had less inflammation and oxidative stress (which can cause DNA damage) than the rats with unlimited calories.

The young rats with unrestricted calories -- who were studied when they were 6 months old -- had 52% less liver inflammation and oxidative stress than the old rats with unrestricted calories.

"This finding suggests that even slight moderation in intake of calories and a moderate exercise program is beneficial to a key organ such as the liver, which shows significant signs of dysfunction in the aging process," Leeuwenburgh says in a University of Florida news release.

No major difference was seen between the rats with restricted calories and those who also exercised.

What about longevity? The study didn't check how long the rats could possibly live.

More rats in the calorie-restricted groups lived 24 months than those whose calories weren't restricted, but it's not clear if the difference was due to chance.

SOURCES: Seo, A. Antioxidants & Redox Signaling, March-April 2006; vol 8: pp 529-538. U.S. Department of Agriculture: "Nutritive Value of Foods." News release, University of Florida Health Science Center.