SIKEN substitute custard cheesecake from SIKEN. Siken® Lemon Cheesecake Custard Replacement is a meal replacement for weight control. Its delicious flavor of cheesecake and lemon, as well as its contribution of 13 vitamins and 15 minerals, make them a delicious way to take care of yourself. This product is indicated to replace meals. Siken® Protein Substitute, Protein and Vitamins, helps you lose weight or maintain your weight within a low calorie diet.