Exercise is not a great means to lose weight.

To lose weight, you can do this two ways: eat fewer calories than you burn or burn more calories than you eat.  You must have a negative calorie balance to induce weight loss.  There is not a magical pill that will transform or suspend the laws of physics and allow you to lose weight without change.  Even the “miracle” of bariatric surgery requires change, and the difference with surgery is it forces change.  

It is true that the more you exercise, the more calories you burn.  I do not deny this fact, but let’s face reality, most of us do not burn a lot of calories exercising. The average male weight in the United States is about 195 pounds.  Walking at a good pace of 3.5-4.0 miles per hour will burn about seven calories a minute for the 195-pound person.  So 30 minutes of exercise will burn about 210 calories or a little less than a candy bar’s worth of calories.  So, to truly make a dent, you need to exercise harder or longer.  

The bottom lines:  All physical activity burns calories.  Even sitting or sleeping expends calories and requires energy, but exercise alone is too slow to allow meaningful weight loss and maintenance.  You must both limit intake and burn more calories to have a lasting effect.