It is well known that calorie restriction — a dietary regimen based on low calorie intake in absence of malnutrition — increases longevity and delays the onset of age-associated disorders in short-lived species, from yeasts to laboratory mice and rats, and not only — the same effects also occur in rhesus monkeys.
Fasting — the abstinence from all food, but not water — is the most extreme form of calorie restriction for humans. It is psychologically difficult to follow, and its advantages are controversial. However, cycles of prolonged fasting that last two or more days, and are separated by at least a week of a normal diet, not only protect normal cells and organs from a variety of toxins and toxic conditions, but also increase the death of many types of cancer cells. Furthermore, cycles of prolonged fasting protect against damage to the immune system and induce its regeneration, shifting hematopoietic stem cells from an inactive state to a state of self-renewal.
Now, results from a study (A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan) published in Cell Metabolism June 18, 2015, show the effects of a calorie-restricted diet that mimics fasting: it promotes regeneration of multiple systems, and extends longevity.
The study included, in addition to experiments carried out in mice, testing in unicellular organisms (yeasts), and a pilot clinical trial in humans. By using yeasts, the researchers uncovered — at a cellular level — the mechanisms triggered by fasting. Mice, which have relatively short life spans, provided details about the lifelong effects of fasting. Finally, the pilot study in humans indicated that the results from the yeast and mouse studies are applicable to humans.
In mice, the regimen consisted of a very low calorie/low protein fasting-mimicking diet, which was administered for cycles of 4 days twice a month. In the periods between the fasting-mimicking diet, mice could eat any desired amount of food at all times. The regimen started at 16 months of age and lasted for the entire lifespan of the animals. In humans, the fasting-mimicking diet was administered 5 days every month for 3 months (therefore, for a total of 3 cycles). It provided between 34% and 54% of the normal caloric intake, with a composition of at least 9%–10% proteins, 34%–47% carbohydrates, and 44%–56% fat. Study participants were asked to resume their normal diet after the fasting-mimicking diet period. In addition, they were asked to not implement any changes in exercise habits.
In mice, stem cell numbers increased considerably. Various cell types — such as bone, muscle, liver, brain, and immune cells — were regenerated. The animals also experienced better health and a prolonged lifespan, with benefits including reduced inflammatory diseases and cancer, improved learning and memory, and retarded bone loss, without a decrease in muscle mass. In humans, dietary intervention resulted in a decrease of biomarkers predictive of risks for aging, diabetes, heart disease, and cancer.
Valter Longo, lead author of the study, said in a press release: “Strict fasting is hard for people to stick to, and it can also be dangerous, so we developed a complex diet that triggers the same effects in the body. I’ve personally tried both, and the fasting mimicking diet is a lot easier and also a lot safer.” In addition, he told The Telegraph: “I think based on the markers for aging and disease in humans the diet has the potential to add a number of years of life but more importantly to have a major impact on diabetes, cancer, heart disease and other age-related disease.”
In the press release, Longo cautioned against water-only fasting and warned even about attempting the fasting-mimicking diet without first consulting a doctor. “Not everyone is healthy enough to fast for five days, and the health consequences can be severe for a few who do it improperly,” he said.