Transparency is extremely important to us, so we are letting you know that we may receive a commission on some of links you click on from this page. See our disclaimer.

The benefits of exercise are well known — for body and the mind. Usually, we feel better. We even think and learn better.

But what if we exercise and also gain weight?

A new study published in The Journal of Strength and Conditioning Research found that the phenomenon is not only possible, but it can occur fairly easily. The study, “Predictors of fat mass changes in response to aerobic exercise training in women,” found 81 women who were told “that they would be joining a fitness study and would exercise in order to improve their aerobic endurance. The scientists asked the women not to change their eating habits in any way,” according to the New York Times.

After 12 weeks of exercise, some women had lost weight, but others had gained weight.

The study could not determine why this occurred, but the New York Times reports they did discover something else important: “But looking deeper into their data, they discovered one interesting indicator: Those women who were losing weight after four weeks of exercise tended to continue to lose weight, while the others did not.”

Or, as the study states: “Change in body weight and fat mass at 4 weeks were moderate predictors of fat loss, and may potentially be useful for identification of individuals who achieve less than expected weight loss or experience unintended fat gain in response to exercise training.”

The bottom line according to Glenn Gaesser, “a professor of nutrition and health promotion at Arizona State and senior author of the study: ‘What that means in practical terms is that someone who wants to lose weight with exercise' should step on the bathroom scale after a month. If at that point your weight remains stubbornly unchanged or has increased, ‘look closely at your diet and other activities.'”