An insidious scourge that has nothing to do with head trauma is ravaging retired N.F.L. players.

In the past few decades, the N.F.L.’s emphasis on the passing game and quarterback protection has led teams to stock their offensive and defensive lines with ever-larger men, many of them weighing well over 300 pounds. But their great girth, which coaches encouraged and which helped turn some players into multimillion-dollar commodities, leaves many of them prone to obesity problems.

In retirement, these huge men are often unable to lose the weight they needed to do their jobs. Without the structure of a team and the guidance of coaches for the first time in decades, many of them lose the motivation to stay in shape, or cannot even try, as damage to their feet, knees, backs and shoulders limits their ability to exercise.

This is a big reason that former linemen, compared with other football players and the general population, have higher rates of hypertension, obesity and sleep apnea, which can lead to chronic fatigue, poor diet and even death. Blocking for a $25-million-a-year quarterback, it turns out, can put linemen in the high-risk category for many of the ailments health experts readily encourage people to avoid.

“Linemen are bigger, and in today’s world, rightly or wrongly, they are told to bulk up,” said Henry Buchwald, a specialist in bariatric surgery at the University of Minnesota who works with the Living Heart Foundation, a nonprofit organization that provides free medical tests to former N.F.L. players. “Their eating habits are hard to shed when they stop playing, and when they get obese, they get exposed to diabetes, hypertension and cardiac problems.”