Fasting Might Regenerate Human Immune System

Prolonged fasting might do a body good. University of Southern California researchers found that occasionally skipping food for 2 to 4 days put humans and mice on the path to a healthier immune system.

Valter Longo, one of the team’s researchers, explained to The Daily Beast that a “mimicking” fast diet of 750-1050 calories per day for at least 4 or 5 days is sufficient to kick the body in a regenerative state. “Any fasting is better than nothing,” he said, “ [but] 4 to 5 days of fasting are necessary to maximize it’s effects, but they must be done under medical supervision and preferably in a clinic.”

Longo explains that humans can safely do this diet every 1 to 3 months.

The study found that “during each cycle of fasting, this depletion of white blood cells induces changes that trigger stem cell-based regeneration of new immune system cells.” In particular, “prolonged fasting reduced the enzyme PKA,” explains the USC announcement.

Longo said that this is especially valuable for those undergoing chemotherapy or aging, to wipe their overtaxed immune systems clean. This jives with his previous research that fasting can weaken cancer in mice.

It’s unclear how this prescription fits into fasting for weight loss. Recently, I tested the “4-Day Diet,” which consisted of walking all day and eating only 220 calories. I rapidly lost fat, but it was difficult. Even though I tried to keep it as healthy as possible, Longo warns about restrictions this severe.

There is some evidence that so-called intermittent fasting (all-day or partial-day fasting) can improve human longevity, and systematic fasting has been around centuries. The practice is quite common among the world’s religions. Muslims observe a month-long day fast for Ramadan and Jews go a full day for the High Holy Day, Yom Kippur.

Perhaps there is some wisdom in the old scrolls.