Your body weight is the biggest factor in the number of calories that you burn while exercising. The heavier you are, the more calories you will burn. The reason for this is that a heavier person will expend more energy in order to move around.
As an example, if a person who is 250 pounds and a second person who is 150 pounds go dancing for 30 minutes, the heavier person would burn approximately 350 calories while the lighter person would burn approximately 200 calories.
If the lighter person asks how to burn more calories in order to burn the same amount of calories as the heavier person, the solution is to exercise longer or exercise harder.