This is supported by a decent amount of medical literature.

In mice (and I believe dog) studies, they found that reducing the daily caloric intake for the animals just below "maintenance calories" resulted in like a 20-30% longer lifespan.

Crazy.

I've been experimenting with this myself lately.

I do IF for 20-24 hrs M-F, and I am generally fit and exercise. When I began simply reducing my caloric intake during the week (when I'm also fasting), I lost 15 lbs that I didn't even realize I needed to lose!