When it comes to health, stress gets a bad rap, but experts are increasingly finding that in small amounts, stress is actually good for us. One beneficial type of stress, according to research from Johns Hopkins University: short-term fasting. Intermittent food deprivation—ideally, eating fewer than 500 calories two days per week—mimics the hunger that likely shaped the brains of our prehistoric ancestors, says Mark Mattson, Ph.D., of the National Institute on Aging Intramural Research Program and Johns Hopkins University School of Medicine.
The Paradoxical Stress That Actually Boosts Your Brain
Intermittent fasting has been shown to help reduce obesity, hypertension, asthma and rheumatoid arthritis
His research focuses on hormesis, the good effect that can come from low doses of something that would otherwise be harmful. Going too long without food causes starvation and death. But Mattson’s research has shown that periodic fasting in rodents protects against diabetes, cancers, heart disease and neurodegeneration. In humans, intermittent fasting has been shown to help reduce obesity, hypertension, asthma and rheumatoid arthritis. “Fasting has the potential to delay aging and help prevent and treat diseases while minimizing the side effects caused by chronic dietary interventions,” he wrote in a recent research paper.
The discovery started with the realization that people who eat very few calories, exercise regularly and stay challenged intellectually seem to have sturdier nervous systems, with lower rates of Alzheimer’s, Parkinson’s or stroke. Looking at why fasting might be so beneficial, Mattson’s research concluded that it creates mild stress, which was useful back when we were hunting and gathering. “If you’re hungry, your brain better be working well,” he says. That mental sharpness “triggers changes within neurons, creating resilience,“ he says. “The neurons are more resistant to degenerating.”
The reverse is also true. When people don’t exercise or they overeat, these cells become complacent and less resilient.
Mattson advocates intermittent fasting to build that kind of resilience, restricting calorie intake to 500 calories or less two days a week to lower risks of Alzheimer’s and Parkinson’s. (His own approach is more stringent; three or four days a week, he eats just one lower-calorie meal a day, consisting of vegetables and lean protein.)
These types of fasts have been used for centuries. Even after the feast-or-famine nature of our caveman days, some religions use fasting as part of a regular practice. Many Muslims, for example, fast from dawn until dusk during Ramadan. (Kids, pregnant, breastfeeding and menstruating women, and people who are sick are an exception. Likewise, if you’re considering trying Mattson’s low-calorie days, check with your doctor first.)
But fasting and exercise aren't the only ways to use stress to build resilience: Eating fruits and vegetables help, and not for the reasons you think. While much research has focused on antioxidants and phytonutrients contained in produce, these nutrients haven’t been shown to reduce Alzheimer’s. Mattson says plants’ protective value comes from the low levels of toxins in plants, which protect them from predators.