hear olive oil is fat-free
Good oxymoron there! Oil=fat. However, olive oil is healthy because it is mostly monounsaturated oil; same with peanut and canola oil. But peanut can supposedly cause allergic reactions.
Next in line are polyunsaturated oils; they aren't as healthy, but they're still ok: corn, cotton, and most other vegetable oils.
Then come the saturated oils, which aren't healthy at all: lard, palm, coconut, hydrogenated stuff/partially hydrogenated stuff, etc.