These days, I only use olive and avocado oils (monounsaturated) and beef dripping or butter. I used to deep fry everything in a deep fryer in which the vegetable oil sat for weeks before it was changed. I would also drink two litres of full-sugar coke*. I was very cavalier about my diet. One heart attack and a double bypass later I've totally changed my attitude towards diet. These days I try to eat somewhere in the low-carb/keto/carnivore spectrum. I believe that my health is improving, but just as it took decades of bad eating to get to the point of heart disease, it may take decades to undo. And as a sexagenarian**, I don't have a lot of decades left, while the old age clock is ticking.
*I suppose it's a small blessing that Coke is made from actual sugar (sucrose) here, and not high-fructose corn syrup, but the result was the same.
** For a laugh, watch the Beverly Hillbillies episode "The Clampetts in London". I call it "Granny versus the Sexagenarians".