Is an “Exercise Pill” Coming Your Way?

Researchers are developing pills that provide many of the effects of exercise. But none provides all the benefits of physical activity- a reduced risk of many cancers, cardiovascular disease dementia, diabetes, obesity and osteoporosis.

Health experts are fond of saying, “If exercise were a pill, everyone would want to take it.” And scientists seem to agree. Over the past several years there has been an accelerated push to develop drugs that mimic the effects of exercise. The promise is enormous—such medications could be a boon to people whose physical activity is limited by medical conditions or injuries. They could provide a head start for people who are beginning an exercise program. They could also confer the health benefits of exercise on healthy people who can’t fit physical activity into their schedules or just don’t want to get off the couch.

“While the idea of an exercise pill is a good one, it has many, many limitations,” says Dr. Laurie Goodyear, head of the Section on Integrative Physiology and Metabolism at Harvard-affiliated Joslin Diabetes Center. Just as a vitamin capsule won’t provide all the benefits of a healthy diet, a single pill is unlikely to provide all the benefits of exercise.

How these pills might work

Since regular physical activity has emerged as an important—perhaps the most important—lifestyle approach to staying healthy, scientists have directed increasing attention on the effects of physical activity on the body’s systems, tissues, and cells. Their research has identified many of the molecules that are activated when we exercise and has given scientists ideas about ways to stimulate them even when we are at rest. A review in the December 2015 issue of Trends in Pharmacological Sciences describes several “exercise pills” under development. Although they are far from being tested in humans, they have been shown to do the following in mice:

Alter the composition of muscle. Over time, regular sustained exercise results in an increased proportion of slow-twitch muscle fibers (which convert fat to energy) compared with fast-twitch fibers (which extract energy from sugars). A compound called AICAR has produced this effect in mice, enabling them to exercise longer.

Transform fat tissue. Exercise increases the ratio of energy-burning “brown fat” to energy-storing “white fat.” Injections of an enzyme called irisin have changed white fat to brown, triggering weight loss in obese mice.

Increase the number of mitochondria. Stimulating the production and function of mitochondria—the cells’ power plants—increases the rate at which the body consumes calories and burns oxygen. AICAR, as well as two plant chemicals, epicatechin and resveratrol, increased mitochondrial function in skeletal muscles and heart cells.

Stimulate capillary formation. Epicatechin stimulated the growth of capillaries, the tiny vessels that connect the arteries and veins, increasing oxygen delivery to skeletal muscles.

What’s missing?

The exercise pills under development may mimic some effects of physical activity by remodeling skeletal muscle, increasing oxygen consumption, and boosting metabolism. But the drugs can’t be expected to build bone or slow the rate of bone loss. They probably won’t help your balance or coordination, either. Nor is there any reason to expect the other benefits that come from getting a good workout—better sleep, a sharper mind, and a brighter mood—from a pill. “It will be a long time before we have a pill that duplicates all the benefits of exercise,” Dr. Goodyear says.

The bottom line

There’s a reason your doctor is likely to advise lifestyle approaches to risk reduction before turning to medication. Once you start taking a drug, you increase the chance of experiencing side effects. And when you take several medications, there’s a greater likelihood of drug interactions. Even if an exercise pill were available, it probably wouldn’t provide a free ride to better health.

Physical activity is still the least expensive and most accessible way to stave off many cancers, cardiovascular disease, dementia, diabetes, obesity, and osteoporosis. Try to get at least 150 minutes of moderate activity each week—more is even better.

Harvard Women’s Health Watch

Is an “Exercise Pill” Coming Your Way?