Lose weight and Keep it offPacked with everything you need for a tasty, balanced meal, our shakes can help you lose weight and keep it off as part of the SlimFast 3.2.1. Plan. High in protein and a source of fibre, with 23 vitamins and minerals and no added sugar, they make the perfect calorie-controlled meal that you can shake-up in seconds. And whats more, theres no artificial colours, flavours or preservatives. Substituting two main daily meals of an energy-restricted diet with meal replacements contributes to weight loss. Substituting one of the main daily meals of an energy-restricted diet with a meal replacement contributes to the maintenance of weight after weight loss.