Diet similar to fasting may have numerous health benefits: USC Biogerontologist cautioned against water-only fasting and advises not to attempt FMD-based fasting regime without consulting doctor and seeking proper supervision.

A team of researchers at USC, led by Valter Longo, demonstrates that following a periodic diet that exhibits effects similar to fasting might confer numerous advantages on health, including lowering of abdominal fat, getting smarter and even living longer.

The study was a three-tiered investigation, looking into the effects of periodic fasting on mice, yeast and humans. It was collaboration among researchers and clinicians from USC, Texas, Italy and England. The study was funded by the National Institute on Aging.

Mice, which have comparatively short life spans, provided the opportunity to record lifelong effects of fasting. Using a simple organism such as yeast allowed researchers to understand the biological mechanisms that are triggered by fasting at a cellular level. A pilot study conducted on humans helped provide evidence that the previous study models were applicable to humans as well. The study was published in cell Metabolism.

The recent study showed that mice, following a four-day low-calorie cyclic diet mimicking fasting (FMD), showed a reduction in visceral belly fat and an increase in the number of progenitor and stem cells in various organs, such as the brain, boosting neural regeneration and improving learning and memory.

Bimonthly cycles (lasting for four days each) of a diet similar to fasting were administered to each subject. These cycles, started with mid-aged mice, were seen to henceforth increase life expectancy, reduce the occurrence of cancer, enhance immune functioning, reduce inflammatory diseases, decrease bone mineral density losses and improve learning and memory. The total calorie intake per month was the same for the control and FMD-fed groups, confirming that the results obtained were not confounded by overall dietary restriction.

In a pilot trial conducted on humans, three cycles of a similar diet was administered to 19 participants once a month, over a period of five days. Results showed marked decrease in risk factors and biomarkers for aging, cardiovascular disease, diabetes and cancer. No major adverse effects were recorded.

“It’s about reprogramming the body so it enters a slower aging mode, but also rejuvenating it through stem cell-based regeneration,” Longo said. “It’s not a typical diet because it isn’t something you need to stay on.”

“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,” explained Longo, Edna M. Jones Professor of Biogerontology at the USC Davis School of Gerontology and Director of the USC Longevity Institute. Longo also has a joint appointment at the USC Dornsife College of Letters, Arts and Sciences. “I’ve personally tried both, and the fasting mimicking diet is a lot easier and also a lot safer.”

Furthermore, the diet brought down an individual’s calorie intake almost 34-54% that of the normal. Prepared using a specific composition of macronutrients and micronutrients, it was seen to reduce levels of the hormone IGF-1, which is a promoter of aging and is associated with cancer risk as well.

The diet also increased the levels of IGF BP-3 and reduced glucose intolerance and C-reactive protein without adversely affecting muscles and bone density. Longo has previously demonstrated how fasting starves cancer cells and protects the immune system from chemotherapy toxicity.

For 25 days per month, participants were allowed to go back to their regular diets, after they had finished the treatment – positive results were still reported despite being off the FMD diet.

Longo believes that beneficial effects of the FMD diet can be gained if an individual follows the diet every three to six months – depending on their abdominal circumference and overall health. For obese people, or those predisposed to certain diseases, FMD could be recommended by physicians once every two weeks. A randomized clinical trial including 70 subjects is currently ongoing.

“If the results remain as positive as the current ones, I believe this FMD will represent the first safe and effective intervention to promote positive changes associated with longevity and health span, which can be recommended by a physician,” Longo stated confidently. “We will soon meet with FDA officers to pursue several FDA claims for disease prevention and treatment.”

However, regarding health benefits of fasting, Longo strictly cautioned against water-only fasting and advised not to attempt an FMD-based fasting regime without consulting a doctor and seeking proper supervision throughout the process.

“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 explained. “Water-only fasting should only be done in a specialized clinic. Also, certain types of very low calorie diets, and particularly those with high protein content, can increase the incidence of gallstones in women at risk. In contrast, the fasting mimicking diet tested in the trial can be done anywhere under the supervision of a physician and carefully following the guidelines established in the clinical trials.”

Longo also warned diabetic participants about adopting a fasting or FMD diet while receiving metformin, insulin, or any similar drugs. He added that participants with a BMI of less than 18 should not follow this diet.