Meal Replacement Powders (or MRPs) offer you convenient and complete nutrition in protein shake form. Meal Replacement Powder Shakes are similar to, and often confused with Protein Shakes. Both are marketed as powders, bars and in ready-to-drink formats. And both MRPs and Protein shakes do supply lots of protein. But Protein Shakes provide mostly protein with only insignificant amounts of other nutrients like carbs, fat, fiber and vitamin content. So Protein Shakes shouldn't be considered complete meals in and of themselves. Meal Replacement Powders are basically fortified protein powders. They contain the same kinds of protein you'd find in Protein Shakes (blends of whey protein, casein and milk protein, egg protein, or even soy protein) but manufacturers have added healthy sources of fat and carbs plus modest amounts of vitamins, minerals and fiber to make them more satisfying and nutritionally complete.