"The heaviest athletes are more than twice as likely to die before their 50th birthday than their teammates, according to a Scripps Howard News Service study of 3,850 professional-football players who have died in the last century."
Many of these athletes likely had untreated or inadequately treated obstructive sleep apnea (OSA). The heavier NFL players tend to have large necks. Increased neck size (greater than 16 inches in men) is a risk factor for OSA, whether the increased neck size is due to fat or muscle. Obstructive sleep apnea increases the risk of various types of heart disease, including coronary artery disease, heart attack, and congestive heart failure.
An earlier 1994 study found that "offensive and defensive linemen had a 52 percent greater risk of dying from heart disease than the general population."