Weight is the gravitational force acting on the object in the downward direction. According to the rule of buoyancy, all fluids apply an up thrust force in the upward direction. Hence, the air exerts an upward force (buoyant force or up thrust) on our body and makes us slightly lighter than we actually are. So the weight shown on the weighing scale would be less than 42 kg .Thus we can say that our actual weight / mass will be slightly more.