Joey Chestnut ate 71 hot dogs in 10 minutes on July 4.
He narrowly missing his previous record of 74.
Scientists have studied the bodies of competitive eaters like Chestnut.
They found that their stomachs don't contract normally.
Business Insider says competitive eaters can relax their stomachs to hold more food.
The sport can take a toll on normal kidney, liver, and heart functioning.
