Butter, margarine, applesauce, shortening or bananas can all be used as substitutes for vegetable oil when making brownies. Butter, margarine and shortening are high-fat substitutes for oil, while using applesauce or a banana can provide a low-fat alternative.
Butter is made with milk, so the brownies taste a bit creamier if butter is used as a substitute. Margarine is made primarily of vegetable fat, so it is an effective alternative to oil and provides less calories than butter. Margarine also does not affect the taste of the brownies. Both butter and margarine should be melted before using. Shortening is solid vegetable oil, so simply heat before using.
Applesauce can match vegetable oil cup for cup while providing less fat and calories. Pureed banana can also be used as a healthier alternative, but it may alter the taste a bit. Use 3/4 to 1 cup banana puree for every 1 cup of oil in the recipe.