Clearly, the claim that we lose 21 grams of tissue at the time of death is totally scientifically unfounded: in every few seconds the mass is the same, and then it decreases with time. However, though, there is no indication of whether it is a coincidence or a deliberate correspondence, but 21 grams is also the approximate mass of all the electrons in the average human body. 21 grams the weight of the hummingbird, the weight of the soul.