Why are cooking methods important when it comes to lowering fats, salt and sugar? Different cooking methods have different effects and need different things. Methods such as frying usually require some fat in the pan, or roasting needing fat to help crisp up the food you are cooking. This makes a difference when it comes to trying to lower the fat/sugar/salt within the dish, and it is recommended that you choose a cooking method which doesn't need any fat. Cooking methods such as slow cooking help keep in flavour, which lowers the need for additional salt and sugar.