 [ Symptoms ] my sister is sick and in bed 95 of the time how many calories does her body need to maintain  my sister has illnesses that keep her in bed almost all the time how many calories should she take in for her organs to function she does not eat very often [ Disease ] it is difficult to say how many calories she needs because i do not know her height weight or which illnesses she has some illnesses increase metabolic rate even when a person is not active this webmd calculator can give you an idea of her general caloric needs <link> but i recommend seeing a registered dietitian to better assess her calorienutrient needs and provide nutrition recommendations some dietitians can visit people at their home so ask her doctor for a referral otherwise go to eatright org to find a dietitian near you