Meal replacement shakes will definitely help you lose 10 – 20lbs, but that’s it! And you can’t stay on a replacement shakes forever. When you go back to eating real food, you’ll instantly see an increase in body fat. That’s part of the gimmick. When you gain all your weight back and then some, what are you going to do? Well of course start back up on the replacement shakes, because they helped you lose 20lbs before. It’s a viscous, unhealthy cycle.