Evidence is accumulating that eating in a 6-hour period and fasting for 18 hours can trigger a metabolic switch from glucose-based to ketone-based energy, with increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity.
Until recently, studies of caloric restriction and intermittent fasting focused on aging and the life span. After nearly a century of research on caloric restriction, the overall conclusion was that reduced food intake robustly increases the life span.
Intermittent fasting elicits evolutionarily conserved, adaptive cellular responses that are integrated between and within organs in a manner that improves glucose regulation, increases stress resistance, and suppresses inflammation.
Cells respond to intermittent fasting by engaging in a coordinated adaptive stress response that leads to increased expression of antioxidant defenses, DNA repair, protein quality control, mitochondrial biogenesis and autophagy, and down-regulation of inflammation.
How much of the benefit of intermittent fasting is due to metabolic switching and how much is due to weight loss? Many studies have indicated that several of the benefits of intermittent fasting are dissociated from its effects on weight loss. These benefits include improvements in glucose regulation, blood pressure, and heart rate, and abdominal fat loss.
Despite the evidence for the health benefits of intermittent fasting and its applicability to many diseases, today’s diet of three meals with snacks every day is so ingrained in our culture that a change in this eating pattern can be difficult. The abundance of food and extensive marketing in our culture are also major hurdles to be overcome.
I’ve found a community focused on IF that I follow for both inspiration and guidance, Gin Stephens, author of Fast. Feast. Repeat & Delay, Don’t Deny. Her blog, books, and Facebook page are full of support!
Intermittent fasting diets fall generally into two categories: daily time-restricted feeding, which narrows eating times to 6–8 hours per day, and so-called 5:2 intermittent fasting, in which people limit themselves to one moderate-sized meal (500 calories) two days each week. With guidance and patience, most people can incorporate IF into their lives.