Burn 3500 calories over for lose one pound of fat. If you want to burn 3500 calories in one day , you must go to step by step . Step 1: First of all calculate your BMR  i.e  Basal Metabolic Rate . Our body needs to maintain general functions like breathing and digestion. You should need to eat minimum number of calories per day. Step 2: By using calorie calculator calculate the how many calories burn while sitting, exercising , lifting weights, ...