Older people who eat a low-calorie diet may reap a benefit even greater than a slimmer waistline -- it may extend their lives, according to a new study.

In apparent proof that it's never too late to begin eating healthier, a strict low-calorie diet increased the life span of aged mice by more than 40 percent, the Associated Press reports of the University of California research.

While prior studies have shown that healthier eating can extend lab animals' lives, the new research was performed on 19-month-old mice -- the human equivalent of about 60 to 65 years, the AP reports. The better diet appeared to immediately slow the aging process, allowing the low-cal diet mice to live up to six months longer than litter mates fed a standard diet.

While study results on lab mice often mimic those later performed on people, it's still unproven that calorie restriction would similarly affect older humans, the researchers stress.