I saved a portion of the survey I wrote about previously because it touches on a subject I've been slow in approaching: Is government intervention the best way to reduce the alarming level of obesity in America?

In the survey, about a third of respondents say that government has some responsibility for our nutrition. I'm not sure if that percentage sounds high or low; I do know that in the circles I frequent, government's role comes up quite often. At the first Museum of Science "Let's Talk About Food" forum I attended, I was particularly struck by how many discussion groups offered government-based solutions when they were asked how to combat obesity: soda taxes, tax rebates for joining the gym, required classes in nutrition for parents, even banning vending machines.

Even adjusting for our location that evening in the People's Republic of Cambridge, I found that to be a lot, and I'm someone who's leaned to the left since junior high. At 53, I've finally concluded that this truism will not hold for me: "If you're not a liberal at 20, you have no heart, but if you're not a conservative by 40, you have no brain." (Or, it does hold, and I just have no brain. Opine as you wish.)

On this question, however, I've come down far more toward the middle than I usually do. I loathe the corporate interests that bang the drum for personal responsibility while denying that they also have responsibility for the nation's expanding waistline. I am convinced that part of the reason we're getting fatter, collectively, is that food-products manufacturers and marketers are laboring — and spending — intensively to make us that way. They may spout moderation, but the more they sell, the more they make, period.

But even if craven forces are working against me, I am still responsible for my health. Even if those corporations were to reform, en masse, overnight, I would still have to abide by a wholesome personal discipline for my own good.

The problem is that personal responsibility alone, as a public-health strategy, is not working, and we pay quite heavily, collectively, when people overeat. Increases of type 2 diabetes, heart disease, cancer and other ailments are directly traceable to obesity, and since we pay our medical insurance in large pools, the increased costs are shared. This is the collateral damage of overeating, the equivalent to second-hand smoke — or one of them; have you seen this?

So even if conservatives don't like it, we share the perils of someone's overeating, and that gives us a shared imperative to do something about it. Those who are concerned can organize in small groups, but to have broad effect, we need something broader, and that's what the government is.

The most obvious example of collective governmental action is the military — I may want to defend my home against marauding hordes, but I can't buy, say, my own B2 Stealth bomber or my own aircraft carrier. For many other reasons beyond that, we've decided it makes sense to attack the problem together.

It makes sense in this case too. Because personal responsibility is where this solution has to start, I'm down with those who want the least amount of government intervention, but "least" does not mean "none." We'll know when we're doing enough — the American waistline will start reducing, rather than ever-expanding.