People choose the Slim.Fast plan because it works - it"s easy, it"s tasty and it doesn"t mean giving up all your favourite snacks. You simply choose a Slim.Fast meal for breakfast and lunch and prepare your own healthy evening meal, up to 600 calories. And to help maintain your energy levels you can snack up to 3 times a day The milk shake powders are a Slim.Fast favourite. A deliciously creamy milk shake in a powder format that you can mix with fresh skimmed milk.