like exercises the yoga does not work on the muscles and heart .
it works on the nervous system and vital organs.
so surprisingly it weight does not matter with yoga . whatever your weight type and size is yoga does balance you to the optimum best for you. if you are overweight the yoga will make you thin, if you are underweight the same yoga asana will put weight on you.
if you are aiming at building muscles like a super human than yoga is not the fit for you. as the yoga thinks that such body is not healthy.
the power really does not exist in the muscles. the yoga will build your stamina and believe me you will have enough stamina to strain yourself easily compared to such muscle men.
the body is governed by the nervous system and the vital organs. if these are strong then there will be quite a few effects of the age.