As my colleague Olga Khazan has written, a subsequent analysis by the Commonwealth Fund found that things like heart disease, diabetes, and respiratory disease were contributing to some of the increased mortality among middle-aged Americans. There are now 30 million Americans living with diabetes, more than three times the number living with the disease in the early 1990s. And a recent study has suggested that diabetes might be more of a factor in American mortality than was previously thought—perhaps the third leading cause of death in America, after cancer and heart disease. (Diabetes is prone to under-counting because the official cause of death is often something else.) Obesity and diabetes have been shown to disproportionately affect people with a high-school education or less—the same group who are disappearing from the labor force.

“Obesity and diabetes are disabling, and they are one explanation for reduced labor-force participation,” Andrew Stokes, a Boston University professor and one of the authors of the diabetes study, told me.

Indeed, of the half a dozen men (and one woman) in North Carolina I talked to who had dropped out of the labor force, many told me of physical challenges that have made it difficult to work a regular job. Charles Lucas, 52, said that he had worked in fast food for a decade until his body got to a place where he could no longer stand. He’s had a few heart attacks, he told me, wheezing as he stood in line to apply for disability benefits. He’s been rejected for disability before. “I don’t know what I could do anymore” for work, he told me. He lives with his father, who gets Social Security.

John Crain, 43, used to work in construction, until alcoholism, divorce, and a death in his family led him to drop out of the workforce. Crain, who is currently homeless, is trying to get his life back together, but spends most of his days holding a sign by the side of the road asking for money. (He makes about $50 a day, he said.)

What is making men sicker than they used to be? I had thought it might be that the difficult jobs worked by Americans over their lifetimes might have worn them down physically, especially after I talked to Sandra White, 49. She could barely walk, and has had multiple surgeries on her back. She spent most of her life waiting tables and doing cleaning jobs on construction sites. The work has impacted her body, she told me. “It’s strenuous work, and it took a toll on my back,” she said.

But Krueger says that jobs are less physically demanding than they used to be, and so it doesn’t make sense that jobs would now be exacting a worse toll. What’s more, he said, workplaces have gotten safer over time, so Americans should be experiencing fewer work-related ailments.

What’s changed may be how people have reacted to pain, he said. Before, they worked through it. Now, they go to their doctors and get on pain medications. Doctors may be prescribing these pain medications too frequently: Recent studies have shown that doctors who prescribe opioids are more likely to have patients that use the drugs chronically.