You are here and read this post which probably means that you are working hard to build muscle but you gained just a little muscle mass and it suddenly stopped and you are now wondering why. There are some possible reasons that might explain to you why are you not gaining muscle mass even if you train hard and eat a lot.  1. You are not consuming enough calories Probably the biggest reason why your muscles don't grow. If you don't consume enough calories you can't build any muscle. You need to feed your muscles with macronutrients to make your muscles to grow.  One of the reasons why are you not consuming enough calories can be that you are afraid of gaining body fat and you want have shredded body, but you should know that by eating clean and training hard in the gym it is very hard that you will gain body fat. To support muscle growth your calories intake should be between 18 to 20 calories per pound of bodyweight. If you eat only cle...