Kelly, 54, has been chewed out by obesity-bias fighters, subscribers of Outpatient Surgery Magazine where the article appeared, and his bosses at Penn, who issued a statement saying his "comments do not in any way reflect" the health system's views.
In response, Kelly has expressed what even critics call "heartfelt" remorse.
Rob Portinga, a gastric-bypass patient who now blogs as FormerFatDudes.com, posted Kelly's mea culpa: "I have issued an apology [in the magazine] and have answered every e-mail I received from this mistake. . . . I blew it. I was not respecting the dignity of my patients. I didn't recognize that this is a different audience than the comedy clubs. Of course, I will revamp my comedy routines now that I know the potential hurt some jokes can inflict."
Kelly moonlights as a stand-up comic at such venues as the Casba Comedy Club in Wildwood and St. Anastasia's parish hall in Newtown Square, according to his "healing through laughter" webpage, which declares: "Tired of subjecting his staff and patients to his jokes, he now brings his brand of clean humor to the stage."
Kelly did not respond to requests for comment from The Inquirer, but his twin brother, Michael, a lawyer in their hometown of Wilmington, sent an unbidden e-mail: "I know of no doctor who is more passionate and concerned about his patients, all of them."
Indeed, Kelly has received high patient-satisfaction ratings at Penn, health system spokeswoman Susan Phillips said. Kelly was also popular at Temple University School of Medicine, where he had been director of sports medicine and received several "teacher of the year" awards.
So how could he make such a mistake - and why has his lapse hit such a nerve?
One answer, activists say, is that obesity bias is at last becoming socially unacceptable, and those who cling to it are increasingly viewed as ignorant.
That may be why Outpatient Surgery Magazine editor Dan O'Connor became a secondary target of ire.
O'Connor - who declined to comment for this article - refused to take the August column off the magazine's website until four days ago, despite pressure from activists and Penn. O'Connor also sent letters warning activists not to reproduce or link to the copyrighted material lest they face a lawsuit.
In an editorial last month, O'Connor lamented "the perils of political correctness" and said "maybe" Kelly's column crossed the line.
"But we will not muzzle him," O'Connor wrote. "We apologize to those we offended, and we march on."
On her website, blogger "Diva Taunia," a Nashua, N.H., entertainer who underwent gastric-bypass surgery, denounced O'Connor's "nonapology."
Another reason for the fury over worn-out fat jokes published in an obscure trade magazine: Healers are supposed to know better.
"The last place an obese person should feel scared to go is a doctor's office, yet that's one of the top places where obesity bias is prevalent," said James Zervios, communications director for Obesity Action Coalition, the Florida-based advocacy group that marshaled protest last week after learning of Kelly's column.
Physician David L. Katz, a nutrition expert who founded Turn the Tide Foundation in 2007 to fight the obesity epidemic, has taken his colleagues to task for blaming weight struggles on the strugglers.
"Have you noticed that two-thirds of American adults and a rapidly rising proportion of the global population are overweight or obese?" Katz wrote in a recent Huffington Post column. "Has it not occurred to you that something larger than the will power or motivation of an individual might be in play?"
Jefferson Medical College cardiologist Joseph Majdan - who experienced derision from coworkers until he lost weight - believes doctors must not treat compassion like a white coat, which can be shed at the end of a shift.
"Being a physician is a profession and a vocation," he said. "You have to be an exemplar of compassion and empathy 24/7."
Kelly would likely agree. In blog posts on OrthoSupersite.com, in a video for doctors on stress reduction, and in an interview on Oprah radio, Kelly preached faith, family, humor, and "blessing not stressing." He sounded more like Patch Adams, the doctor/activist/clown, than Rodney Dangerfield.
"The irony," Kelly wrote to Portinga, "is that I really do try to keep my comedy positive. A priest once told me that 'Humor is a gift of the Holy Spirit.' Clearly, the Holy Spirit was not behind most of these jokes."
Contact staff writer Marie McCullough at 215-854-2720 or firstname.lastname@example.org.