That's kinda the whole point of the keto diet, you trick you body to use fat as it's main fuel by eating almost no carbs and low to moderate protein, but high fat. It makes fat the only available fuel, so you body adjusts to burn it. You have to make sure you eating enough fat or your body won't get into ketosis (the state where it's using fat as it's main fuel). But yall probably know all that already.
But yeah. Doing keto turns everything on it's head. The stuff you always though was bad is suddenly good for you, and the stuff you thought was good for you is suddenly bad.
Butter, bacon, and eggs are now some of the best things you can eat.