A sparse diet helps rats maintain strong, healthy muscles well past middle age, Canadian researchers say.

Elderly rats fed a nutrient-rich but restricted diet were able to keep up with much younger rodents, physiologist Russ Hepple and his colleagues at the University of Calgary's kinesiology department found.

Russ Hepple
(CBC)

"If you can think of an 80-year-old still being able to go out and have as active a lifestyle as someone in their early 20s, when they're considered largely to be in the prime of their life, I think that's a very attractive thought," Hepple said.

One group of rats had their calories cut by 40 per cent, while a second group ate normally for the three-year study.

Mimicking benefits of low-calorie diet

Elderly rats fed fewer calories were able to keep up with the speed of younger rats.
(CBC)

The team doesn't suggest humans should severely cut back on what we eat. For the average active person, a similar diet  would be drastic and possibly destructive to muscle, especially if the calories come from protein.

"The body will borrow protein from its muscles – heart, liver, kidneys etc. – to make up the deficit," said exercise physiologist Lee Coyne.

The scientists hope the research will lead to ways to mimic the effects of limiting calories to reap health benefits without limiting what we put on our plates.

As for the immediate implications, Hepple said: "Probably get regular activity, and don't eat too much. I mean it sounds so simple and boring, but that happens to be true, and sometimes truth is like that."

The study will be published in this week's Journal of Gerontology: Biological Sciences.