Expert: John Shea - 9/12/2006

Question
Is it true that all humans have the same size bones?  A doctor on a reality weight loss television show stated that all humans have the same size bones and there is no such thing as big bone and small bones.  Various bone lenghths are possible but not size.

Answer
Dear Pamela
This doctor is dead wrong.  There is tremendous variation in size and shape of human bones (some more so than others).  For example, if you exercise a lot, many microscopic cracks will form in your bones and bone cells will grow into the cracks to repair them.  As a result, someone who exercises a lot will have much thicker bone than someone who does not exercise.  Diet, diseases, parasites, evolutionary responses to temperature and many other factors also influence the dimensions of human bones.
It is true that the sizes of bones in a population will cluster around certain average values.  This is because some aspects of bone growth are under fairly strong genetic control.  But any such values are statistical approximations, not fixed limits of bone dimensions.
FWIW:  What the doctor have meant to say is that one cannot blame obesity on a person being "big boned".  Bones simply do not make up that much of one's weight to tip the scale, as it were, between normal weight and obseity.
Sincerely,
John Shea