Now, oversimplification runs both ways.
Not all fat is “good”: the fat from feedlot beef and factory-farm pork and chicken, which are fed loads of carbohydrates, has a different nutritional profile, higher in heart-disease-linked Omega-6 fatty acids, than those that eat their natural diets and forage on pasture, which
are rich in Omega-3s.
(The Eat Wild website collects the scientific literature on the differences.) And not all carbs are “bad”: complex carbohydrates from whole-plant-based foods cause less of a spike in blood sugar than do refined carbohydrates, i.e. processed foods.