Between all our talk of the obesity epidemic as a public-health problem and our actual, often moralistic attitudes toward the overweight lies a distance much greater than any extra-large waistline. For evidence, look no further than this week's revelation that Gov. Christie, a man not known for his diffidence, underwent weight-loss surgery in secret.

Christie managed to keep his secret for some three months before the New York Post got him to admit to the procedure, which equipped him with a stomach-constricting silicone band. The New Jersey governor's cloak-and-dagger approach, along with the widespread assumption that the surgery is meant to make him more presentable as a presidential candidate, speaks to the shame and stigma that still attach to matters of weight.

That an ambitious, affluent star of the self-styled party of personal responsibility felt he had to resort to a surgical reduction of his digestive capacity demonstrates the true difficulty of weight loss for many. Indeed, about 200,000 Americans get weight-loss surgery every year. Still, the notion that fat people just have to put down the fork remains prevalent, and it may explain the governor's unfortunate but understandable decision to conceal his surgery.

Christie has taken more than his share of unhelpful scolding for his weight problem. In 2011, a Washington Post columnist advised him to "eat a salad and take a walk." In February, after he good-naturedly made fun of his weight in an appearance on the Late Show With David Letterman, a White House physician grimly speculated about his prospects for a heart attack on CNN, inviting a classic Christie outburst to the effect that she was an attention-seeking "hack."

As with smokers and drug addicts, derision and ostracism of the obese is too often paraded as heartfelt concern. Free will is of course an element of these public-health problems, but so are factors largely beyond individuals' control. If we're really concerned about healing the victims of a bona fide epidemic, we should focus on what they can do to get thinner, not dwell on what they did to get fat.

Christie says he has struggled with his weight for 20 years, and his surgery is unlikely to be the end of that struggle. If he continues to be more forthright about his challenges, it will only help other overweight people deal with theirs - even as it helps the rest of the country come to a more compassionate understanding of a serious national health problem.