Valter Longo

Longo, director of the Longevity Institute at the University of Southern California, believes that the secret to staving off the ills of old age is a diet designed to trick your body into thinking it’s fasting. He translated his years in the lab, researching the effects of fasting and calorie restriction, into a 2018 book called The Longevity Diet, which preaches a low-protein, plant-based eating style with regular periods of fasting. This diet, he claims, shifts the body’s metabolism and enhances the power of cells to help protect against chronic diseases like Type 2 diabetes and cardiovascular disease. Some small studies have found that a fasting-mimicking diet—the kind Longo ­advocates—helps people lose weight and body fat, lowers blood pressure and decreases levels of a hormone linked to aging and disease. Ideas like his are catching on: according to a 2018 survey from the International Food Information Council Foundation, intermittent fasting is this year’s most popular diet. Now, Longo is studying whether a fast-mimicking diet improves cancer ­outcomes—and can help prevent the disease in the first place. —Mandy Oaklander