If I do spinning for about 6 hours a week for three weeks, How much body fat will I be able to lose?

the diet that you follow ultimately determines your body composition not the exercise that you participate in. the healthier your diet the greater the physical changes you will see in your body. exercise only provides the stimulus, your diet provides the nutrients that your body needs to run at optimum levels of efficiency. the more whole foods and the less chemicals that you ingest on a daily basis the healthier you will be