Chart of pizza consumption by age and gender. Can anyone explain to me why guys stop eating so much pizza after the age of 19?

Here is a bar chart (from Reason who got it from the USDA) showing the US daily consumption of Pizza by age group and gender.

The distribution seems right to me by age and gender.  The only thing I am curious about the large percentage drop-off for males past age 19 into the next category, 20-39.

Female consumption drops off 28% (18% to 13%) but males drop 38% (26%-16%).

Any guesses as to why?

Source: Via Reason