If you cook with vegetable oil, such as soybean oil and vegetable oil, it doesn't matter much if you put more vegetable oil because it is easy to digest. But the animal oil you want to put, whether lard or butter, is indigestible, or it is easy to precipitate after a long period of digestion, which is why eating animal oil will make you eat less, eat more, gain weight more easily, and make you feel worse.