A recent headline proclaimed “Americans blame obesity on willpower, despite evidence it's genetic.” I think the headline writer meant “Americans blame obesity on lack of willpower,” but never mind that for now. Let's talk about the implications of the statement: “it's genetic.” Are obese people really helpless victims of their genes?

There is a grain of truth to that notion. There are heritable conditions that make it literally impossible for individuals to control their eating. But even those unfortunates can have a normal weight if someone else controls their food intake; the fat does not miraculously appear on their bodies. And while these are serious conditions that require lifelong management, they are — fortunately — extremely rare. For all intents and purposes, these conditions have no relevance to this discussion.

The overwhelming majority of obese subjects have what is called “common obesity.” Researchers have looked for genes associated with this condition, too. An impressive array of brainpower, not to mention money, has been thrown at this problem. And what have these researchers found? They have discovered genes correlated with tiny variations in body mass — in some instances as little as 2 ounces. Even these tiny correlations diminish or disappear if you exercise. A 2013 paper in PLoS Genetics compared individuals with high and low genetic risk scores for obesity. When the researchers dropped from their analysis the bottom 25 percent in terms of exercise, they found the difference between the high and low risk score groups was about three pounds.

Stephen O'Rahilly, professor of medicine and clinical biochemistry at Cambridge University and an internationally recognized expert on the pathogenesis of obesity, told me “There is no such thing as genetic obesity. There is a genetic predisposition to obesity, which can be nullified through exercise.”

What about those folks who have been on 20 different diets and still are obese? Do they have some miraculous ability to store energy as fat without overeating? Actually, no. Researchers at Columbia University studied a self-selected sample of 10 such “diet-resistant” patients. They taught these patients to estimate portion sizes and keep detailed diaries of their food intake and exercise. But they also measured actual food intake and caloric expenditure, and they found that these patients were eating twice as much they said they were — and overestimating their daily physical activity by one-third.

Is anyone surprised? Life is a long process of learning to be honest with oneself. I don't know anyone who has that down perfectly. But that's no excuse for giving up the struggle.

And this is where that much-maligned quality — willpower — comes in. Willpower means self-control plus self discipline. That is precisely what is called for. Willpower will get the job done, and nothing else will.

The essence of humanity is that we are moral beings with free will. Choices have consequences, which is why we need to strive to make the right choices, and to teach our children to make the right choices. We need to start exercising more skepticism toward those who tell us otherwise, and who follow that message with a pitch for their pet program, which for some reason always seems to involve making the rest of us throw even more money at the pharmaceutical industry and the manufacturers of medical devices.

We live in a society in which installing a porthole in someone's stomach to drain half-digested food after eating too much is an FDA-approved therapy, while expecting people to take responsibility for the most basic tasks occasioned by their biological makeup is frowned upon.

There is no such thing as a gene that makes it impossible not to be obese. We are not powerless slaves to our genes. Indeed, we have a great gene pool, honed by five hundred million years of evolution. Our Paleolithic ancestors trekked for miles in search of the right kind of wood for making spears, they used those spears to take down wild horses and woolly rhinoceroses, they banged out stone tools and used them to cut up their kills, and then they shouldered the meat and carried it home. All this took tremendous amounts of energy. The lesson is clear: Our bodies evolved to be used. If you can't fit into your jeans, don't blame your genes.

Patrick D. Hahn lives in Roland Park, where he spends at least 90 minutes a day walking. He can be reached at patrickhahn@hotmail.com.