Give up dinner? Landmark study shows daytime eating could be the new fountain of youth.

A new study out of UT Southwestern on mice has found that caloric restriction increases longevity, which isn’t exactly front-page news. However, the intriguing part is that this study found that the time of day the mice were fed had a big effect on their life spans.

Researchers found that restricting the calories mice ate by 30 to 40% increased their longevity by 10%. But mice that were fed the restrictive diet only while active at night lived 35% longer than those that ate whatever they wanted whenever they chose.

If this type of diet were adapted for a human’s biological rhythms, we’d eat low-calorie diets during the daytime. So if you’re the type that prefers breakfast over dinner, a long life could be in the cards. But if you love a four-course dinner, it may be hard to make the adjustment.

Bottom line: If the diet is found to work the same way in humans as it does for mice, when we eat will become almost as important as what we eat. It could also lead to changing the times we wake up and go to sleep. Who wants to stop eating at 3 p.m. and then go to bed hungry at 11 p.m.?

“It’s pretty clear that the timing of eating is important to get the most bang for your buck with calorie restriction,” Dr. Joseph Takahashi, Ph.D, one of the lead researchers on the study, said in a news release.

“We have discovered a new facet to caloric restriction that dramatically extends life span in our lab animals,” said Dr. Takahashi, the Loyd B. Sands Distinguished Chair in Neuroscience. “If these findings hold true in people, we might want to rethink whether we really want that midnight snack.”

The study also makes the interesting case that low body weight isn’t necessarily tied to longevity.

“This shows that at low body weight, this popular yardstick of health (body weight) is not a predictor of life span,” said Dr. Carla Green, Distinguished Scholar in Neuroscience at UT Southwestern.

Obviously, this study was performed on mice and there’s a long way to go before we can be sure that this type of drastic dieting will expand human life or doesn’t come with any dangerous side effects. But it is compelling to imagine that by simply adjusting what and when we eat we could live up to 35% longer.

That would push the life span of the average American male from 75 to 103 and female from 81 to 109.