Have you tried putting on some weight but your attempts have been thwarted by your ‘fast metabolism’.
It’s not your metabolism! You are likely a very active person; lots of exercise, lots of moving around or a combination of both.
If you are looking to put on some weight and build some muscle then you are
going to need to increase your intake to a point where you are consuming more than you are expending. Only then will weight gain be possible.
To ensure that the weight is going on as muscle [as much as possible] you will need to perform adequate resistance/strength training. Also you need to be consuming adequate protein.
