My Dear Friend,
The best way to have a healthy physicque is to eat a balanced diet and do regular physical exercise.
I suggest you increse intake of proteins in your diet , along with that do physical exercise for at least four times a week.
Please do not take the diet supplements advertised on TV or on other media as one can never be sure of the contents of such products.
If you wish to take diet supplement take the one suggeted by a doctor.
Gaining height after age of 20 is usually not possible, but in my experience I have seen some people gaining 2-3 inches of height after doing proper Yogasanas. I suggest you try it.
Dr. Anamay Kamalakar Bidwai