Protein is the simplest macronutrient to look at, which is why I am starting with it. As a soccer player, to maintain your muscle mass you need to be eating 1 gram of protein per pound of body weight, and if you're trying to gain lean mass, then up that to 1.5 grams of protein per pound of body weight. Simple as that. You can get a more in-depth look at protein, how it works and why it's so important here, but for this article, we'll keep it easy.

The best sources of protein are:

• Animal Meat! Always try to go organic/grass-fed/free-range whenever possible. Make sure to not eat only lean protein; fats from animals are good for you. If you still believe the phrase "The less legs the better", please stop doing so. Trying to bring fats back from the dark side is covered more here****, and briefly below.
• Fish, along with other seafood (shrimp is protein packed). Tuna is great, but make sure to keep it to 2 servings or less a week due to mercury content.
• Eggs. They are cheap, great sources of protein and healthy fats, delicious and easy to cook. What more do you want? If you still believe the stigma that eggs are bad for your cholesterol, read this and this. Expect a post dedicated to eggs in the future.