Five days of hunger a month could significantly reduce aging and age-related medical conditions. But don’t start fasting just yet.

Fasting and science

Image in Creative Commons / via Wiki Commons

It’s one of the ‘hottest’ trends in nutrition, although it’s not exactly a new idea. Laboratory research has repeatedly shown that calorie restriction (CR) has anti-aging properties, but the lab tests were conducted on animals such as nematodes (worms) and rats — so the same might not stand for humans. Furthermore, extreme fasting can have damaging effects on the body, reducing bone and muscle density. Now, for the first time, two studies show that extreme CR likely yields good outcomes for humans.

Writing in Nature Communications, researchers at the University of Wisconsin–Madison and the National Institute on Aging report that rhesus monkeys exhibited the same effects as the rats and nematodes, making it more likely for the results to translate to humans.

In the first study, researchers describe a monkey that started on a 30 percent calorie restriction diet when he was 16 years old, and is now 43, establishing a record of longevity for the species (the rough human equivalent of 130). Meanwhile, in the second study gerontologist Valter Longo at the University of Southern California (U.S.C.) reports that you don’t need to fast all the time for the CR to make its effects. “All” you need to do is repeat the hunger days a few times a month.

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Previously, Longo and colleagues found only three rounds (5 days every month for three months) of alternating between a fasting-mimicking diet and a business as usual diet improved health. Results suggested improved physical condition, less body fat and blood glucose, and lower levels of proteins associated with cardiovascular diseases.

This is an improvement from the previous idea that you need to always fast, but I know quite a few people who would argue that a life extended in such a way is not really a life worth living.

Should we fast?

Rozalyn Anderson, a researcher in the Wisconsin study, does not really disagree. She doesn’t really recommend going for such a diet:

“Life is difficult enough without engaging in some bonkers diet,” she says. “We really study this as a paradigm to understand aging. We’re not recommending people do it.”

Indeed, this approach could turn out to be a one-size-fits-all treatment when it comes to age-related conditions, as calorie restriction “delays the aging and vulnerability. Instead of going after diseases one at a time, you go after the underlying vulnerability and tackle them all at once.”

In fact, the second study, which recruited human subjects, had a 25 percent dropout rate because it was so difficult to maintain. People ate a plant-only diet which included vegetable soups, energy bars, energy drinks and a chip snack as well as mineral and vitamin supplements. It also featured nutrients designed to manipulate the expression of genes involved in aging-related processes. The health benefits included decreased body mass and better levels of glucose, triglycerides, and cholesterol, and lasted for up to three months, even after subjects returned to their regular diet. Lean muscle mass and density remained unchanged, which is also encouraging.

However, you really shouldn’t start extreme fasting. We really recommend against it. As Anderson says, this is a matter of scientific research — not some DIY diets.