Answer:
Usually, here, all of us get confused. Weight is the force with which the earth attracts the body. Gram is the unit of mass in FPS system of units. Now a days in SI units we use kg as the unit of mass.
Physics relates weight W and mass M by the expression W = M g. Here g is the acceleration due to gravity. SO if one is having 50 kg ie 50000 g mass, then his weight will be got after multiplying this by 9.8 m/s^2.
But the same weight could be expressed as 50 kg wt. Here kg wt is another convenient unit which equals to g newton. Hence instead saying 50 x 9.8 newton it will be more easier to say 50 kg wt.
So the dialogue goes this way.
"Hello, what is your weight?"
"I am 63 kg."
The answerer just stops with kg but it is understood that he means 63 kg wt. Because weight is already there in the questioner's statement.