For every 3,500 calories you burn, you’ll lose a pound. However, it turns out that slimming down is more complex than the golden rule preached by fitness pros. Shedding pounds isn’t so precise, according to Ralph La Forge, a physiologist and managing director of the Duke Lipid and Metabolic Disorder Training Program at Duke University Medical Center in Durham, N.C.

Although weight loss does, indeed, depend upon the “calories-in, calories-out” equation, you may at times exercise without losing weight. For example, a brisk 30-minute walk burns 200 calories – only about half the amount in that bagel you ate this morning (minus the cream cheese).

In addition, gender and genes matter. Women, who store fat differently than men and have a harder time losing fat around the abdomen, tend to lose weight more slowly. And some people are just born with a faster resting metabolism, so they burn calories more quickly.

So what can you do to nudge the scale down? Keep these tips in mind.

Do exercise a little more. Gradually increase the time and intensity of your workouts to burn more calories. Just walking 15 minutes more, for example, will help you shed an additional 100 calories. 

Do work more muscles. The more muscle groups you work, the more energy your body uses. Thirty minutes of weight-bearing exercise, such as walking, hiking, dancing, tai chi and some forms of yoga, burns more calories than 30 minutes of stationary cycling or some types of resistance training. It also builds strong bones.