lol watso can add or remove more water to the backpack..
anyway if a person loses weight, then they also lose some muscle … if a person is 20kg overweight, then he (or she) has leg muscles to support that weight … carrying all that extra weight, is just constant muscle building exercise for the legs ..
these women put watso to shame … carrying all that water on the head would create strong neck and leg muscles - and also good for the posture