In one study, participants who followed a diet akin to fasting for five days a month showed an average reduction in biological age of 2.5 years.

According to a news release, the fasting-mimicking diet was created by senior study author Valter Longo’s lab at the USC Leonard Davis School of Gerontology to replicate the effects of a water-only fast while still supplying essential nutrients. When you water fast, you merely consume water for a full day or two.

While there are risks associated with fasting, there are also potential health benefits. Research on cells and animals has shown that fasting can reduce the incidence of some malignancies, type 2 diabetes, and cardiovascular disease.

It is believed that calorie restriction or fasting triggers autophagy, the body’s process of removing damaged and aging cells to create room for new ones. According to The Cleveland Clinic, it starts when cells are under stress or are starved of nutrients, and it normally declines with age. This means that it is crucial in delaying the aging process.

About half of the 100 participants in the study were instructed to follow the FMD for five days a month for three months, with the remaining 25 days being spent eating their typical diet. The other group consumed their usual food. Males and females between the ages of 18 and 70 participated.

According to the study, participants in the FMD group had lower levels of liver and abdominal fat and were less likely to develop diabetes based on blood tests and MRI scans. These findings are linked to a lower risk of metabolic syndromes, which include diabetes, liver disease, and cardiovascular disease. Additionally, it raised their lymphoid-to-myeloid ratio, which suggests a younger immune system. The study’s authors, who published their findings in Nature Communications on January 20, said that these variables may be used to calculate biological age.

A person’s biological age is determined by the state of their cells and tissues, whereas their chronological age is the number of years they have lived. Since there is no “normal” way for human cells to look at any particular age and younger cells may not always imply better health, the word is still up for debate among experts.

While “fasting,” participants could consume items like soup and energy bars

The FMD is a low-calorie diet that is low in carbohydrates and protein and high in unsaturated fats. Participants in the five-day fast were given vegetable-based soups, energy bars, energy drinks, chip snacks, tea, and a supplement from Longo’s nutrition tech business, L-Nutra, that had high concentrations of vitamins, minerals, and vital fatty acids. Participants consumed approximately 1,100 calories on day one of the FMD and 720 calories on days two through five. They had unlimited access to food throughout the day.

Longo said in a press release: “This is the first study to show that a food-based intervention that does not require chronic dietary or other lifestyle changes can make people biologically younger, based on both changes in risk factors for aging and disease and on a validated method developed by the Levine group to assess biological age.”

The study only included 100 people, most of whom were healthier than the average US citizen, according to the authors, so the findings might not apply to a larger group.

“More research in a variety of demographic and health groups would be necessary to truly understand the benefits of fasting for all people,” said professor Clare Bryant, who does innate immunity research at Cambridge University in the UK and was not involved in the study.

Prior research on mice has connected FMD to both stem cell regeneration and a reduction in the adverse effects of chemotherapy.

“It’s not unreasonable to think that, during ages 40 to 60 at least, this regime twice per year may add three to four years of healthy life, maybe more, in those with higher BMI, blood pressure, blood sugar, etc.” said David Clancy, a lecturer at Lancaster University in the UK who specializes in the biology of aging and was not involved in the study, to BI.

However, he pointed out that the diet is “pretty harsh,” and at the end, some people might find it difficult to go through their workday. “Scheduling days four and five for weekend days would be sensible,” he stated.

According to Clancy, developing a healthy fitness routine can produce comparable or even superior outcomes and be sustained into old life.