Dr Cohen: They give you the same sugary taste that we all crave naturally but they don't contain as many calories as carbohydrates. They are mainly used industrially to improve the taste of foods without making them too calorific. They can also be used at home in cooking, depending on the type of sweetener. Aspartame isn't very heat-resistant and can't be used in cooking, but can be an excellent sweetener for dishes that have already been cooked or prepared. Acesulfame is heat-resistant and can be used to make cakes and sweet foods.