Intermittent Fasting: Is It Safe for People Over 50? 

Inflammation is a potential culprit in dementia as well. And new data reported in 2024 in Cell Metabolism suggest that strategic fasting may defend the brain against cognitive decline. “This was the first study in humans to look at the effects of intermittent fasting on cognition and the brain,” says study author Mark Mattson, adjunct professor of neuroscience at the Solomon H. Snyder Department of Neuroscience at Johns Hopkins School of Medicine in Baltimore. In the study, 40 people ages 55 to 70 were assigned either to the 5:2 fasting plan or to a generally healthy diet. The fasting group lost more weight, plus they saw greater improvements on tests of executive function and memory.

Although most people who try intermittent fasting do so to shed pounds, there are clearly other perks that seem to be independent of the weight loss. “Even without weight loss, we think that this type of restricted eating can contribute to the metabolic fitness of cells,” says Miriam Merad, M.D., chair of immunology and immunotherapy at the Mount Sinai School of Medicine. That means cells appear healthier and even biologically younger in people following this type of diet, as reported in a study in Nature Communications in 2024.

Changes at the cellular level, not all of which are understood, seem to produce the positive outcomes associated with intermittent fasting. For example, fasting raises levels of a chemical in the body that activates longevity genes known as sirtuins. Sirtuins protect against disease, boost the repair of DNA, and quell the inflammation behind arthritis, atherosclerosis, asthma and other chronic conditions.

Satchin Panda, professor of the Regulatory Biology Laboratory at the Salk Institute for Biological Studies in San Diego, says intermittent fasting supports the body’s circadian clock, which regulates the body’s sleep/wake cycle. “Repair happens during sleep,” he says. It takes about five hours to digest the last meal of the day. “If dinner is at 6 p.m., the gut is still working until 11 pm. Downtime for repair happens after that. The gut needs seven hours of downtime” for repair. This schedule also supports healthy insulin levels, important for diabetes risk.

One study that got lots of attention in early 2024, but hasn’t been peer-reviewed or published yet, suggested that intermittent fasting may cause heart problems. But it’s been widely questioned as being a look-back study based on only two days of self-reported food logs.

Should you try intermittent fasting?

Intermittent fasting can be an easier way to trim back food consumption than other methods, says Vicky Pavlou, a researcher and dietitian at the University of Illinois at Chicago. “It’s a way to reduce calories without having to track calories, which a lot of people don't like,” she says.

To do it safely, see your doctor first. “If you’ve never done intermittent fasting, you might want to get a checkup,” says Mattson, who takes all his nourishment between noon and 6 p.m. “Go on intermittent fasting for a few months and then get another checkup and see if there are any measurable effects.”

Experts stress that any fasting routine should be accompanied by exercise. “People who become inactive quickly lose muscle mass,” says Panda, whose research demonstrated that intermittent fasting improves cholesterol and blood pressure in firefighters. He recommends brisk walking 30 to 45 minutes every day and simple strength training exercises to maintain your muscle — a particular concern for older individuals.

You’re more likely to be successful if you pick the right form of fasting for you. “The easiest thing for most people to do is TRE [time-restricted eating], as opposed to, say, 5:2 intermittent fasting, where two days a week you eat hardly anything,” Mattson says. TRE also simplifies gathering with others over meals, which fosters social connections. Some people may like the 5:2 plan, however, because they can eat like they normally do five days a week without worrying about straying outside an eating window.

Easing into TRE

For the first month, try to eat all your meals within 10 hours, Mattson suggest. In month two, shrink the feeding window to eight hours. Some people even reduce further, to six hours as time goes on. During the fasting hours, drinking water and zero-calorie beverages such as black coffee or tea, is allowed.

“The first week will be a little hard,” Panda warns. “You will feel a bit hungry.” But over time, the pattern should feel comfortable. If it’s too challenging, practice the method just five days a week at first and gradually work up to seven days.

To make the most of time-restricted eating, Panda says, your last meal of the day should be three hours before you go to bed to aid digestion and optimize sleep. The next morning, “wake up, wait two hours, and then have your first calorie,” he says. That helps sync with your circadian clock.