Fat substitutes are designed to mimic one or more roles of fat in foods such as providing texture and moisture. They vary in calorie density from none to 9 calories per gram. Some can achieve fat's qualities with less of the substitute. The specific substitute used depends on its properties and regulations. Carbohydrate-based substitutes have little effect on nutrient absorption while olestra may affect fat-soluble vitamin absorption. Labels must adhere to regulations for fat and calorie claims.