Otherwise your body will turn them into fat as you sleep. When you read labels, value low carbs above low fat. Also try to eat small meals all day long rather than a few big meals. This keeps your metabolism churning and avoids insulin spikes which lead to fat loss problems. You want to get most of your calories from protein.
Protein is especially important for muscle gains.
1 to 1.5 grams of protein per pound of lean muscle in your body is good. If you are trying to cut, and eating low carbs, you might want to eat extra protein to make up for protein being burned for fuel instead of carbs. A protein shake after the workout is good to speed the healing to the muscles. That is, I go for fat calories over carb calories. One thing I must emphasize is eating the right amount.