Namely the triceps on the back of your arm and the small coracobrachialis muscle on the front. As the triceps is the biggest muscle on your arms, targeting this muscle with the right exercises can make your arms bigger and stronger. For most beginning weight lifters, keeping your diet simple is ideal. Eat enough good food so that you adequately recover between each workout. If you’re hovering around 15-18% body fat, but dream of having just 10% body fat one day, simply focus on getting bigger and stronger.