High Protein Food
You need to understand which sources of proteins are the best and when should be eaten. Nowadays it is much easier. We have Internet and all nutrition information has to be put on a packaging. You simply read it and know what you eat and how much calories (energy) there is. Apart from basic information provided there are also other important factors like biological value or glycemic index.
Biological value shows how much proteins provided witch certain food, can be used by your body to build muscles. Obviously the higher value is the better source you have. The best sources of proteins are: meat (beef and poultry), fish, eggs and dairy (especially cheese).
Chicken - one of the best and commonly used by all body-builders. It's full of high quality proteins (about 25% with biological value of 79) and does not contain much fat. Remember not to eat it with skin as skin itself is very fatty. The best choice is to eat breasts. It should be eaten about 150-300 grams a day.
Beef - pretty much the same value as chicken (25% of proteins with biological value of 80). You should always look for lean meat cuts but it is also worth trying a minced beef as this form is simply cheaper (unfortunately contains more fat). Additionally contains vitamin B12 and iron. It should be eaten at least 2-3 times a week.
Fish - as a source of proteins it is actually even better than meat. Similar to beef or chicken it's about 25% proteins but with slightly higher biological value of 82. Apart from proteins it is also great source of fatty acids Omega-3 that has huge influence on health. It can be canned tuna, frozen or wet haddock/cod or salmon. Try eating at least twice a week.
Eggs - second best protein source. Egg proteins have phenomenal biological value of 88 up to 100 but there's only 11% of them in white and about 16% in yolk. However yolk is full of fat and that's why it is less recommended, especially when you want to reduce weight. Similar to fish eggs are good source of Omega-3. The best way to prepare them is to simply boil them for about 5-6 minutes (hard boiled eggs). You'll void additional fat (e.g. frying) and it will be easier to separate white from yolk (if you do not want to eat yolk).
Dairy - really good source of proteins. The biological value is about 80 but amount of proteins varies for different products: about 5% for milk or 22% for cheese (average). Dairy, because of casein which is assimilated longer, is especially recommended to be eaten in the evening, before you go to bed. Unfortunately cheese has loads of fat and that's why cottage cheese and skimmed milk are better choice.
Since you need all kind of proteins it is recommended to provide all of them. There's no only one, magic protein that can sort out all your needs. It is also important to keep proteins at higher level whole day, so consider eating more meals during a day. Obviously relatively smaller ones what will prevent you from gaining fat. Do not forget about providing other elements like carbohydrates and fat. These are responsible for power you need to do exercises.