"I settled on the 16-hour fast, where I’d limit eating to an eight-hour window every day. As Mattson explains, the liver stores glucose (the body’s main energy source when you are regularly eating carbohydrates) for about ten to 12 hours after a meal. When you fast for more than 12 hours, your body switches from glucose metabolism to fat metabolism, which leads to a bunch of positive adaptive cellular stress responses. So, if you fast for 16 hours each day, you’re receiving the benefits of those adaptive responses without limiting your total caloric intake."https://www.outsideonline.com/2181151/what-i-learned-year-intermittent-fasting
The 2014 medical journal article by Dr. Mattson referenced in Outside Online is entitled "Meal frequency and timing in health and disease." There is a long list of references for those interested in learning more.
Proc Natl Acad Sci U S A. 2014 Nov 25; 111(47): 16647–16653.
Published online 2014 Nov 17. doi: 10.1073/pnas.1413965111