It can be seriously frustrating to hit the gym over and over again, only to see zero weight-loss results.

Heaps of research hint that eating habits are the most critical factor in losing weight (and keeping it off), but a new study from Saint Louis University says not to count out the right kind of exercise. People who slimmed down through cardio alone or a combo of cardio and cal cutting lost the same amount (about 7 percent of their body weight over four months) as those who shed weight solely through dietary restrictions.

The big "but" here? The first two groups lost more fat weight and kept more lean mass—the stuff that helps you burn more calories at rest, gives you more energy, and can prevent injury. Try adding a moderate amount of walking, running, or cycling to your plan (the combo group in the study we mentioned did about four hours a week).