Food composition in the form of a flour comprising at least 50% of protein, less than 15% of carbohydrates and 35 to 50% of plant fibres; preferably the carbohydrate content is less than 10%, advantageously less than 5%; this composition may be used as a substitute for wheat flour in the preparation of foods such as pasta, bread, bread sticks, bakery products and pastries and constitutes the basis of a method for improving the appearance of a person by achieving a loss of weight which is beneficial from the aesthetic point of view.