Why You Shouldn’t Exercise to Lose Weight

Many of us are lacing up our sneakers and starting (or restarting) exercise regimens in hopes of shedding unwanted pounds. Unquestionably, aiming to be more active is a good thing. But if the main reason is to lose weight, your New Year’s resolution could very well backfire.

For starters, exercise—at least the kind most of us do—is typically ineffective for weight loss. Take walking, for example. A 150-pound person who walks briskly for 30 minutes will burn, on average, around 140 calories. That’s equal to one can of soda—not exactly a great return on your investment of time and effort. It’s much easier just to skip the soda.

Studies overall show that doing moderate-intensity aerobic exercise such as walking for 30 minutes a day, five days a week—the amount recommended for good health—typically produces little or no weight loss by itself.

When moderate exercise is added to diet, the results are equally unimpressive. Pooling data from six trials, researchers found that a combination of diet and exercise generated no greater weight loss than diet alone after six months. At 12 months, the diet-and-exercise combo showed an advantage, but it was slight—about 4 pounds on average. In another review of studies, the difference was less than 3 pounds.

In studies where exercise has produced meaningful weight loss, participants burned at least 400 to 500 calories per session on five or more days a week. To achieve that, a 150-pound person would need to log a minimum of 90 minutes per day of brisk walking or 30 minutes of running 8-minute miles. In short, sessions need to go well beyond what most of us are willing or able to do. And even if we manage to exert that much effort, our bodies often compensate by boosting appetite and dialing down metabolism, effects that over time limit how many pounds we shed.

When exercise fails to meet our weight-loss expectations, we often sour on it and stop working out. In a study of 30 overweight people who participated in a 12-week exercise program and were interviewed afterward, this response was typical: “It was quite disappointing that I didn’t lose a single pound and . . . it kind of made me give up.” Another respondent who failed to lose weight described her exercise experience as “like banging my head against a brick wall.” It’s pretty safe to assume she didn’t go back for more.

Perhaps the biggest problem with exercising to drop pounds is that it turns physical activity into punishment—a price we have to pay for a slimmer body. How many times have you heard someone say (or said yourself) “I’ll need to do extra exercise” after eating too much during the holidays or at a celebratory dinner? We treat exercise as a form of self-punishment for being “bad.”

By framing exercise as penance, we’re unlikely to enjoy it or to keep doing it for very long. That’s the message from a study in which researchers asked middle-aged women to write down their thoughts about physical activity. Those who used terms like “calories” or “weight” were labeled “body-shapers,” while those who didn’t were called “non-body-shapers.” Both groups weighed about the same on average. The body-shapers were more likely to view exercise as a struggle, while the non-body-shapers tended to say that it made them feel good. Given such attitudes, it’s not surprising that the body-shapers exercised considerably less than the non-body-shapers.

The takeaway is that we’re more likely to perceive exercise positively and actually do it when we focus on our well-being rather than our weight. For some, the incentive may be an improved mood or less stress. Others may find that exercise makes them feel physically and mentally stronger or more in control of their lives.

Of course, the benefits of physical activity extend well beyond these. It’s been shown to reduce the risk of heart disease, stroke, cancer, diabetes, dementia, depression, colds, back pain, osteoporosis and premature death. It can also improve sleep, boost energy, fend off old-age feebleness and even enhance our sex lives.

What’s more, while it’s not very helpful for melting away pounds, exercise can prevent weight gain and improve your appearance by increasing muscle mass and reducing visceral fat, the type indicated by a large waist that’s linked to heart disease and diabetes.

Imagine a pill with this long list of benefits. We’d all be clamoring for it.

So by all means, strive to exercise regularly in the new year. It’s perhaps the most important thing you can do for your health. But to improve the odds of success, focus on how movement helps you feel better physically and emotionally—and forget about how it moves the needle on the scale.