SlimFast ready to use milkshakes can be used on the go as a meal replacement drink for weight control. Packed with everything you need to help meet your nutritional needs, the milkshake contains 204 calories per serving and is high in protein and fibre. Slim Fast milkshake bottles are ready to drink and are designed as a meal replacement for weight control helping to meet your nutritional needs and are part of the Slim Fast 3. 2.1 Plan. Each portion contains 23 essential vitamins and minerals with 204 calories, 15g of protein per serving and 4. 9g of fibre. Key Features of Slim Fast Strawberry Flavoured Milkshake Designed for use on the go High in protein High in fibre23 essential vitamins and minerals per portion Tasty Strawberry flavour