Only way for someone to loose fat is by burning it(exercise)? a gymnast told me fat can leave the body though sweat and urine. i gave him a odd look

Well....: Turns out that exercise does indeed burn calories - about 600 calories per hour for vigorous exercise. ( 3600 cal is a lb of fat ) That in turn leads to sweating, so some of what he says is true. However, calorie loss through urine is negligible unless of course you are taking one of the newer anti diabetic medications which poison the kidneys ability to reabsorb sugar.