The final option is to collectively restore our diets to a more natural state through regulations. Until recently, all humans had no choice but to eat a healthy diet with modest portions of food that were low in sugar, saturated fat and salt, but high in fiber. They also had no choice but to walk and sometimes run an average of 5 to 10 miles a day. Mr. Bloomberg’s paternalistic plan is not an aberrant form of coercion but a very small step toward restoring a natural part of our environment.

Though his big-soda ban would apply to all New Yorkers, I think we should focus paternalistic laws on children. Youngsters can’t make rational, informed decisions about their bodies, and our society agrees that parents don’t have the right to make disastrous decisions on their behalf. Accordingly, we require parents to enroll their children in school, have them immunized and make them wear seat belts. We require physical education in school, and we don’t let children buy alcohol or cigarettes. If these are acceptable forms of coercion, how is restricting unhealthy doses of sugary drinks that slowly contribute to disease any different?

Along these lines, we should ban all unhealthy food in school — soda, pizza, French fries — and insist that schools provide adequate daily physical education, which many fail to do.

Adults need help, too, and we should do more to regulate companies that exploit our deeply rooted appetites for sugar and other unhealthy foods. The mayor was right to ban trans fats, but we should also make the food industry honest about portion sizes. Like cigarettes, mass-marketed junk food should come with prominent health warning labels. It should be illegal to advertise highly fattening food as “fat free.” People have the right to be unhealthy, but we should make that choice more onerous and expensive by imposing taxes on soda and junk food.

We humans did not evolve to eat healthily and go to the gym; until recently, we didn’t have to make such choices. But we did evolve to cooperate to help one another survive and thrive. Circumstances have changed, but we still need one another’s help as much as we ever did. For this reason, we need government on our side, not on the side of those who wish to make money by stoking our cravings and profiting from them. We have evolved to need coercion.