If you really want to see that number on the scale drop, then you have to think twice about what you put in your mouth. People who simply cut calories to slim down lose about 2 pounds a week. At the same time, people who exercise but don’t restrict calories drop less than half a pound in the same period.

Why doesn’t physical activity produce the same pound-dropping results as calorie restriction? One thought is that though exercise burns calories, it doesn’t rev your metabolism. It also doesn’t prevent your metabolism from slowing as you lose pounds. As you slim down, via any method, your metabolism slows incrementally with your weight loss, and despite what many believe exercising doesn’t keep that from happening. As you lose weight, you burn fewer calories through exercise alone. For example, a 150-pound person who works the elliptical for 30 minutes burns about 306 calories. After losing 10 pounds, that person will burn about 286 calories doing the same workout. So to burn 306 calories, you’d need to extend your workout.

Think diet and exercise combined equals more weight lost? Not so, research shows people who diet and exercise for weight loss drop the same amount of weight as people who only diet. Yet, research reveals that people who are larger or have more muscle burn more calories, even at rest. Likewise, those who diet and exercise are more likely to keep the weight off than their counterparts who simply eat less.

Bottom line: slimming down for the long term, you need to create an energy deficit by eating fewer calories, and by increasing the number of calories you burn through physical activity.