If you've been trying to drop a few pounds recently, you’ve probably heard of intermittent fasting. This Hollywood-endorsed regimen goes by quite a few names – there’s the 5:2 diet, the 16/8 method, the warrior diet, eat stop eat … the list goes on – but the underlying idea is the same: to lose weight, we shouldn’t try to restrict what we eat, but when we eat.
It might sound like just another celebrity fad diet, but there’s actually quite a lot of science supporting intermittent fasting – if not for its (probably not, in fact, remarkable) weight-loss potential, then for its surprising health benefits in other areas. It’s been shown to potentially reduce symptoms of psoriasis, help to ward off infections, and lower the risk of various cancers and metabolic diseases. According to a new study published this week in Nature, there might be yet another benefit to intermittent fasting: it might be able to extend your lifespan.
“Time-restricted feeding (TRF) has recently gained interest as a potential anti-ageing treatment for organisms from Drosophila [fruit flies] to humans,” the study explains. “We developed an intermittent TRF (iTRF) dietary regimen that robustly extended fly lifespan and delayed the onset of ageing markers in the muscles and gut.”
As you’re probably aware, humans and fruit flies are quite different in many ways, but there’s a good reason the research team chose these teeny test subjects. Research increasingly supports the idea that the success of any intermittent fasting regime depends on how well it follows our bodies’ natural circadian rhythm, and fruit flies have a pretty similar day/night cycle to us. They also share about 70 percent of humans’ disease-related genes. Best of all, they age in similar ways to humans but only live for about two months, meaning scientists can study the entire lifespan of a test subject without having to lose decades of their own.
To measure intermittent fasting's effect on aging, the team put their fruit flies on one of four different diets. One lucky group had unrestricted access to food at all times; another group was given access to food for 12 daytime hours only; the third group was made to fast for 24 hours following by 24 hours of unrestricted feeding; and the final group was put on the team’s iTRF regime – 20 hours of fasting, followed by a recovery day of unlimited food.
Of the four diets, only one extended the flies’ lifespan: the iTRF method. Specifically, the team realized, it was the flies who exploited the day/night cycle, by fasting all night and eating only around lunchtime, who lived longer – and that was a crucial clue as to the mechanism behind the effect. They learned that autophagy – the process by which cells in the body break down unnecessary or harmful components and use them to regenerate new cells – kicks in after fasting, but only when the fasting happens at night.
“We found that the life-extending benefits of iTRF require a functional circadian rhythm and autophagy components,” study lead Mimi Shirasu-Hiza explained in a statement. “When either of those processes were disrupted, the diet had no effect on the animals’ longevity.”
By following this regimen, male flies were granted an extra eight days or so – an increase in life expectancy of 13 percent – and females fared even better, extending their lifespan by more than a week and a half, or 18 percent. Even better, the flies’ “healthspan” was also increased: muscle and neuron function was improved, age-related protein aggregation was reduced, and the onset of aging markers in muscles and intestinal tissues was delayed.
Especially intriguing is what the team plans to do with this discovery. Human cells use the same autophagy process to clean and regenerate themselves, and the researchers suggest that the discovery of behavioral changes – or even new drug developments – could stimulate the process, providing the benefits of intermittent fasting without the hunger pangs.
“Any type of restricted eating is difficult,” co-author Matt Ulgherait concluded. “It requires a lot of discipline, and most studies of time-restricted fasting in humans have built in a cheat day to make it more tolerable. It would be much easier to get the same health benefits if we could enhance autophagy pharmacologically, specifically at night.”