When attempting to build muscle mass, it is important to ingest the right foods. If your efforts to add bulk are stagnating, it could be because you have an insufficient nutritional intake. To add bulk, you need to consume at least 4000-6000 calories each day from foods, which are calorie dense. Some examples of calorie-dense foods are pasta, nuts, eggs, bagels, trail mix and steaks. Since vegetables have low calorie-density, keep their intake to a minimum.
Genetics are one of the most important factors in building muscle mass. There is not much you can change about your interior genetics that shape your body, but you can improve the way you look by becoming more tone. Some of us just do not have the bodies that will have large muscles, so accept that and strive for better tone.