According to the British Broadcasting Company reports,  a Taiwanese University professor has determined that large hamburgers are the cause of the rising number of jaw injuries. Hsu Ming-Lung of the National Yang-Ming University, has found that patients are having trouble opening their mouths after eating giant hamburgers in some Taiwan eateries. Difficulties arise when diners try to eat burgers taller than 3 inches. Hsu said a human mouth is designed to gape over objects measuring up to 1 1/2 inches and overextension, such as in an effort to bite into a giant burger, can injure the joint between the jawbone and the temporal bone in front of the ears.

He called on fast-food restaurants in Taiwan to limit the size of their hamburgers to prevent the public from literally biting off more than they can chew, according to a news release.