Mark Mattson, the National Institute on Aging’s chief of neurosciences, has dedicated much of his 20-year career to examining how diet affects brain cells. And based on what he’s seen, he’s jumped on the fasting bandwagon himself. Most recently, Mattson and his colleagues studied the salubrious effects of intermittent fasting, practiced either every other day or 21 hours each day.
Mattson started with three groups of identical mice. Animals in one group ate as much as they wanted. The second group ate a calorie-restriction diet, held to just 60 percent of their normal calorie intake. And the third group ate their fill one day and fasted the next—rinse and repeat. At the end of the experiment, Mattson compared the brains of all the mice. The animals who fared best were those who followed the intermittent regimen.
Mattson believes the mild stress fasting puts on cells increases production of proteins in the brain. These additional proteins foster the growth of new nerve cells as well as shield cells from oxidative damage, both factors that contribute to dysfunction and disease. Early research suggests that intermittent fasting may help brain cells stave off disorders such as Alzheimer’s, Huntington’s, and Parkinson’s diseases; it may also ward off diabetes and heart disease.
Fasting 21 hours a day is often easier for people than fasting every other day, says Mattson, and the physical benefits are similar. So when it comes to his own diet, he skips breakfast and sometimes lunch too. While he takes in as many calories as he ever did, he does most of his eating between 6 and 8 p.m. each day.
It took him about a month, he says, to adjust to the change. Now, he says, he doesn’t find the regimen difficult.
But unlike many members of the Calorie Restriction Society, Mattson isn’t betting on living an abnormally long time; his hope is simply to have a healthy old age. The best-case scenario as he sees it? “That we could all live to be a healthy 90, then die in our sleep.”
How to do it: Begin by skipping breakfast for a couple of weeks, then slowly begin to skip lunch as well. You can eat as much as you want, but only during a two- to three-hour window in the early evening.
You’ll still need to eat healthy foods—fruits, veggies, and lean meats or other proteins—and be sure to eat until you’re full. Leave a few hours between your meal and bedtime to avoid lying down with a full stomach, which can cause acid reflux and keep you awake.
What to expect: The side effects of intermittent fasting can include low blood sugar, low energy, and irritability; neither should be a major problem if you’re healthy. Stay hydrated by drinking plenty of water throughout the day.
What to watch out for: Children, teens, and pregnant women should not fast intermittently. Also, if you are on prescription drugs that must be taken with food or if you have a chronic illness, such as diabetes, be sure to talk with your doctor first.