You’ve probably heard by now that not stuffing your face full of calories every day, besides keeping you at a reasonable weight, may also help you live longer. Calorie restriction, as it's called, may extend lifespan by as much as 15%, according to a bunch of recent studies.

The big question: Why the life extension? Thanks to a new study out of Brigham Young University, we have a better understanding of why eating less seems to transform everything from mice to monkeys into Methuselahs.

In the BYU study, researchers tried two diets on two groups of mice. One group got one unlimited food; the other got 35% less calories, though with all of the nutrition needed to sustain a healthy life. The scientists found that the rodents that didn’t get to eat as much sustenance had a almost linear increase in lifespan, and that their ribosomes—molecular machines in cells that manufacture protein—showed slowed-down production.

Now for a little high school biology: Ribosomes use up to 20% of the cell’s energy reserves to build the proteins that allow the cell to operate, and they are complex biological factories that are not efficient to destroy when they eventually break down. It’s much more practical for them to be repaired on the fly, but to do this properly, they need to slow down. The researchers found that this work stoppage can, in turn, slow down the aging process because the extra time not spent cranking out proteins is used to self-repair, allowing for a more efficient molecular machine that will pump out a higher-quality protein product.

As for those longer-lived mice? They seemed to feel better in the long run, too. “The calorie-restricted mice are more energetic and suffered fewer diseases,” said senior author John Price, Ph.D. “And it’s not just that they’re living longer, but because they’re better at maintaining their bodies, they’re younger for longer as well.”

The technique hasn’t been confirmed to work yet in humans, but there’s obviously no harm in cutting back your calorie intake as long as you are getting the proper nutrients. For help on doing that, check out our list of 11 food swaps to cut 500 calories a day from your diet.