Shopping for protein supplements can be confusing. For instance, some are labeled as meal replacement powders (MRPs), while others carry a stern warning like, “Use as a food supplement only. Do not use for weight reduction.” What does it mean? What are the different types of protein supplements for?

All of us want to increase muscle strength, keep fat cells down to an acceptable minimum, and feel energetic and healthy. That means making the most-appropriate nutritional choices, so when you’re trying to decide on a protein product, you need to understand the differences between MRPs and other protein supplements.

The Lowdown

While high-quality MRP products such as Sports Nutrition Technology’s Mrp Plus or American Bodybuilding’s MRP Force Meal Replacement Shake contain fats and carbohydrates, supplemental protein products such as Iron-Tek’s Essential Protein Powder or Pacific Health Laboratories’ Accelerade Protein Drink contain protein but no carbs or fats. For instance, in addition to protein, MRP Force contains 20 grams of carbohydrates, 6 grams of dietary fiber, and 26 vitamins and essential minerals, while Mrp Plus provides a 55/30/10 ratio of protein, carbohydrates, and fat.

And while protein drinks may contain additional nutrients, many do not. Most protein drinks are made almost solely of whey protein isolates because your body doesn’t have to spend a lot of time digesting these before they become useful. And while some protein drinks contain casein, soy, or another protein in addition to whey to deflect some of the insulin response that whey triggers, they never contain the fats and carbs essential in a well-balanced meal.

Strive for Balance

We humans are designed to run on balanced diets that include healthful fats and carbohydrates. Sometimes we tend to forget that the key here is to strike the correct balance and ratio of these dietary components, as evidenced by the increasing number of grossly overweight bodies in our society. But the people who own those bodies didn’t become obese because they ate fats and carbohydrates, but because they ate too many of the wrong fats and carbohydrates.

So, nutritionally speaking, MRPs have a distinct edge over a protein-only product when your aim is replacing a meal. Whether or not you should take them depends on your goals. If you’re trying to lose weight but don’t want to eat meat, for example, you may want to consider replacing one meal per day with an MRP. However, you do need to be careful about the quality of the MRP you choose. Some manufacturers will use a protein blend as a base and merely add sugar and hydrogenated oil so they can call the product a MRP.

People who want to lose body fat while retaining muscle need high protein with low calories, as do those who don’t typically eat nutritious whole foods. MRPs can help both groups consume enough protein without getting too many calories. However, MRPs aren’t appropriate for everyone all the time. People who eat well and have no difficulty meeting their requirements for protein, vitamins, and minerals probably don’t need them. On the other hand, those who need to add more protein to their diets without adding carbohydrates or fats should choose protein powders over MRPs.

—Julie Crawshaw