Increased Longevity Through Intermittent Fasting??

Fruit flies’ aging processes mirror those of humans
Credit: Egor Kamelev via Pexels

Intermittent fasting seems to be quite the buzzword in health and wellness circles today. But does not eating really extend longevity? A recent study of fruit flies reported in Nature in September 2021, indicates that perhaps it does.

What is intermittent fasting, anyway?

Intermittent time-restricted feeding (iTRF) is different from the mainstream dogma of calories-in/calories-out. ITRF limits eating to specific hours of the day or days of the week. (Popular intermittent fasting regimes include 16:8 — in which a person fasts for 16 hours and eats for 8 — and 5:2 in which normal eating occurs on 5 days a week with restricted calories occurring on 2). 

Dr. Mimi Shirasu-Hiza, Ph.D., associate professor of genetics & development at Columbia University Vagelos College of Physicians and Surgeons, led the study with fruit flies. She noted, “Because intermittent fasting restricts the timing of eating, it’s been hypothesized that natural biological clocks play a role.”

Since fruit flies share similar biological clocks and aging processes with humans, Shirasu-Hiza and her team assigned the flies one of four different fasting schedules: 1) a 24-hour window of unrestricted access to food, 2) a 12-hour window of daytime access to food, 3) a 24-hour fasting window followed by 24-hour feeding window, or 4) iTRF, an intermittent time-restricted fasting window of 20 hours followed by a recovery period of 20 hours of unlimited feeding.

ITRF seemed to extend longevity for the flies–with an 18% longer lifespan for females and 13% longer lifespan for males. For these 20-hour subjects, the timing was important. Enduring the fast overnight and breaking it around lunchtime correlated with longer lifespans. 

Imagine if fasting was the key to living longer?
Credit: Bruce Mars via Unsplash

How does this happen?

When fasting occurs long enough and overnight, autophagy (Greek for ‘self-eating’) occurs. This natural process cleans and recycles damaged parts of the cells, thereby slowing aging. 

Other health benefits evidenced in the study included improved muscle and neuron function, delaying the onset of aging markers in intestinal tissues and muscles, and reducing age-related protein aggregation. 

According to Dr. Shirasu-Hiza’s study, “Because both circadian regulation and autophagy are highly conserved processes in human aging, this work highlights the possibility that behavioral or pharmaceutical interventions that stimulate circadian-regulated autophagy might provide people with similar health benefits, such as delayed aging and lifespan extension.”

More concrete studies involving humans, however, have yet to emerge.