Health & Wellness

Fasting Is the Latest Diet

Scientists are getting serious about the notion of abstaining from food for better health

Photo: iStock/Dash_med. 

A Johns Hopkins Medicine neuroscientist is recommending people abstain from eating for 16 to 18 hours a day to reduce their blood pressure, lose weight and live longer.

“We are at a transition point where we could soon consider adding information about intermittent fasting to medical school curricula alongside standard advice about healthy diets and exercise,” says Mark Mattson, a neuroscientist who has studied intermittent fasting for the last 25 years.

In an article published in The New England Journal of Medicine, Mattson cites studies that show fasting tends to improve blood sugar levels while reducing inflammation and stress levels.

If 16 to 18 hours of fasting each day seems daunting, which it is, Mattson also recommends “5:2 fasting”—you choose two days of the week during which you eat no more than 500 calories.

Studies on humans and animals find the practice prompts metabolic switching, causing cells to convert fat in the body to energy. However, since many people eat three meals a day on top of snacking in between meals, that switch, and the health benefits that come with it, doesn’t happen.

While it seems impossible, Mattson says the discomfort that comes with fasting doesn’t last forever. “Feeling hungry and irritable is common initially and usually passes after two weeks to a month as the body and brain become accustomed to the new habit,” he promises.

The diet has to be introduced gradually, too, he says. If you try to go “cold turkey,” you’re likely to fail. Instead he suggests gradually increasing the length and frequency of fasting periods over several months before making the final switch.

If it sounds too good to be true, keep in mind that studies to date have looked only at overweight patients, calling into question whether the diet would provide the same benefits to fit or athletic people. A 2017 study on alternate-day fasting—eating only 25% of recommended calories every second day—saw 40% of all patients dropping out before the study’s end.

The same study, which analyzed 100 obese patients adhering to varying degrees of fasting, came to the conclusion the diet “was not superior to the daily calorie restriction diet with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease.”