I am a somewhat skinny 16 year old. I am 48KG and 167cm tall. I try and eat as much as I can to gain body mass and not have stick man arms etc. I still am not getting much body mass. If I go to the gym for a certain amount of time every week will I gain body mass? If not what are the best ways to gain body mass?
Yes, although your success will depend on many factors. The best way to gain muscle mass is by lifting heavy weights. You will also need to make sure you eat enough, especially enough of protein. How much mass you gain and how quickly depends on how you work out, and also on your genetic make up. Some people gain muscle easier than others. There is a lot of very good information online. Simply google it and follow some of the excellent guides that are out there. Look up what exercises are the best for what you want, how many repetition you should aim for etc. You can also ask for a personal trainer at the gym to create a plan for you. My general advice to you is; whatever you choose, stick to it. Gaining muscle - just like losing weight - is a long process and you will not see results overnight. Think of a tangible goal (gain 5 kgs, squat 50 kgs etc) and work toward getting there, step at a time. Good luck!