I read that if the fat/sugar ratio of a food is less than 40/60, or
greater than 60/40, we will eat it until we reach a biological state
of "satisfied," and then stop eating.  But if the ratio is between
40/60 and 60/40 (e.g., near half fat and half sugar), we will keep
eating well past a biological indication of "satiation."  Is this
true?  Please cite a scientific reference(s) to support your answer. 
Thanks.