>>756178you have to eat approx. 2,000 calories a day, maybe a little more or less depending on your size, sex, age, but you need to eat every day. Fasting intermittently is OK, as long as it isn't longer than 12 hours. Fasting longer than 12 hours has health risks. your body needs a constant stream of fuel to stay alive and healthy. your pain probably isn't cancer, but hunger.