Macronutrients are the parts of the foods we eat that provide the energy for our bodies. However, each of the three main macronutrients (protein, carbs and fats) has a different role in the body, so it is important that we not only pay attention to how much we eat, but also what the foods we eat contain.
Of the three macronutrients, protein is arguable the most essential for both muscle gain and fat loss. After we eat protein, it is broken down by our digestive system into amino acids and it is these amino acids that play a role in the body. Many people are aware that amino acids are the building blocks of muscle, so their role in muscle growth is fairly obvious, and we can use resistance training to force the muscle to adapt and create new muscle proteins by providing enough amino acids to allow the creation of new muscle tissue.
Outside of muscle growth, amino acids are also essential in all other body tissues. Amino acids are major parts of a tissue’s structure and function, and are used to create enzymes that support day-to-day functioning of our bodies, and constitute several ‘peptide’ hormones that are essential for our health. For weight loss, protein also has some other very important benefits that we need to consider.
A higher protein diet allows us to protect muscle; in an energy deficit, we can breakdown muscle tissue to provide amino acids if we do not provide enough in the diet, and as muscle is a key determinant of our metabolism, the body can try to reduce our energy output by reducing muscle mass which, unfortunately for us, is a throwback to our evolutionary survival mechanisms. A high protein diet is muscle-sparing, which is important not just for metabolism, but also general health.
Protein is also the most satiating (filling) macronutrient per gram. This is important as it can help control hunger, which is an obvious bonus during dieting. The final benefit of protein from a weight loss perspective is that it has the highest thermic effect of food (TEF). This means that although the calories from protein still matter, it takes more energy to digest carbohydrates and fats, so in effect, our net energy into the body is lower per gram.
Despite the popularity and relative short-term success of very low carb diets, research has shown that as long as you match protein intake and overall calories, that there is no difference between getting the rest of your daily energy from carbs or fats, and that the real advantage of low carb diets isn’t from the lack of carbs, as some would have you wrongly believe, but an increase in protein intake which demonstrates the amazing properties we’ve just discussed.
http://jn.nutrition.org/content/143/5/591.short
http://annualreviews.org/doi/abs/10.1146/annurev-nutr-080508-141056
http://onlinelibrary.wiley.com/doi/10.1002/oby.20078/full
