You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Weighing machine measures weight.
Weight is the a force by which a body is attracted towards center of earth.
It is in the downward direction.
The air also applies a force in the upward direction due to buoyancy (gases also exert buoyant force)
Hence, the air exerts an upward buoyant force (upthrust) 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 mass will be slightly more.