Often, people equate protein supplements – whether they are whey or casein protein – with gaining weight. The truth, however, is that when they're used correctly, these products can also help you to lose body fat while preserving muscle mass. Whether you’re a bodybuilder on a cut or just looking to get ripped for the summer, protein powders can help. Specifically, though, casein appears to have some unique benefits. But how exactly does casein protein improve body composition? The Science Fairly convincing evidence – and some explanations – can be found in a 2009 study published in the American Journal of Clinical Nutrition. The study gave 24 healthy subjects two diets, consisting of either 25 percent or 10 percent protein. Both diets used casein as the sole protein source. For 36 hours, while following these diets, the subjects stayed in respiration chambers so that the team could measure their energy expenditure, hunger levels and macronutrient use. Increasing the casein to 25 percent served to accomplish several useful things: First, the subjects burned more calories – even while sleeping. Plus, those calories were primarily taken from fat. But the participants in this study also saw a massive – 33 percent – increase in satiety, meaning that they felt fuller than they would have otherwise. Combined with these findings there are numerous studies, including one conducted in 2013, that have found that casein can contribute to the growth of bigger muscle fibers. This growth can help to improve athletic performance while also improving your overall body composition. The Application Okay, so how can we practically apply this research? In order for you to successfully cut, it's important that you operate at a caloric deficit – burning more calories than you take in. At the same time, you also need to be able to maintain muscle mass so that, once all the fat is gone, you have something to show for all your efforts in the gym. As we've seen from the research, casein can help in all of these aspects. By increasing your metabolism while also decreasing your hunger, casein protein will help you lose weight. Because it provides your muscles with everything that they need to rebuild themselves and grow, casein will also help to preserve your lean mass so that it isn't lost during your cut. And what about the performance enhancing benefits? A common problem experienced by people lifting while on a caloric deficit is that they feel weak and lack energy. Casein, because it is highly nutritious, can help to lessen these feelings. This will allow you to get a better workout, and therefore achieve more noticeable results. Read More: What is Casein Protein and Should I Use It? Casein Protein Smoothie and Baking Recipes Better Gains:  Why You Should Be Using Casein Protein to Increase Lean Mass