my fault -

"feed" has two layers of meaning here

1) calorie feed: sugar, whole wheat bread, tofu, butter or even patient's own muscle, can all be converted to calorie, if needed

2) signal feed: it is long known that most cancers are addicted to glucose because of their preference for anaerobic metabolism, which is the basis for FDG-PET scan. This part of the cancer feed by sugar surge is dangerous, because it selects for hypoxic and invasive phenotype of cancer. So, in practical term, sure way for cancer patients to expire quickly is to feed them dunken doughnuts every day.