Soon the U.S. Supreme Court will decide whether making health care coverage mandatory for all Americans is constitutional or not. The principal question is whether the government should have the power to make people buy a particular product – in this case health insurance – regardless whether they want it or not.

Opponents of the new law argue that once Congress can force people to get insurance, it can make all sorts of other requirements as well, if it deems them necessary. Eventually, so the argument goes, this could lead to a future scenario where everyone will be required to eat healthy (e.g. lots of broccoli) and forego simple pleasures like smoking and drinking. So, beware of the “nanny state” before it’s too late.

The fact is that most Americans have been subject to a mandate to buy health insurance for a long time. It’s called Medicare. Contributions to the program are automatically deducted from people’s paycheck, whether they eventually will reap the benefits or not. That’s as mandatory as it gets.

In truth, it is quite clear that there are limits to what the government can do, says Einer Elhauge, professor of law at Harvard University and director of the Petrie-Flom Center in Health Law Policy. “If [Congress] tried to enact a law requiring Americans to eat broccoli, that would likely violate bodily integrity and the right to liberty. But the health insurance mandate does not require Americans to subject themselves to health care. It requires them only to buy insurance to cover the costs of any health care they get.”

But what about the private sector? Is it acceptable, for example, that employers coerce their workers into adopting healthier lifestyle habits, like asking them to quit smoking, exercise regularly and manage their weight?

More and more companies now require employees who smoke, are overweight or have high cholesterol to pay a greater share of their health care costs. According to Mercer, a consulting firm specializing in corporate health policies, about a third of companie with over 500 workers offer wellness programs and give other incentives like insurance discounts. But others, including industry giants like Wal-Mart, Home Depot, PepsiCo, Safeway, Lowe’s and General Mills have chosen a more punitive approach, they describe as “more stick, less carrot.” Wal-Mart, for example, demands “surcharges” of up to $2,000 per year for smokers among its workforce. Others set “health targets” that employees must meet to qualify for lower premiums. Those who fail to meet specific standards may be charged 20 to 50 percent of their policy costs.

Critics say that practices like these are thinly disguised ways to discriminate against less than perfectly healthy workers. Some people suffer from health problems that are not necessarily lifestyle-related and may not always be under their control, they say.

That may very well be. But tobacco users alone consume about 25 percent more health care services than non-tobacco users, according to Greg Rossiter, a spokesperson for Wal-Mart. “The increase in premiums […] is directly related to that fact,” he added.

The message is clear: If we are to succeed in making health care more accessible and affordable, we all must do our part. The employer-based insurance system we have now is not sustainable in the face of ever-rising costs. Nor is a private insurance industry that remains out of reach for tens of millions of Americans.

The Obama administration has emphasized from the start that affordability is an essential component of any health care mandate. But affordability depends in large parts on responsible use. We have a national health crisis on our hands with two thirds of Americans being overweight and one third being obese. We have a childhood obesity epidemic never known before in history. We have an array of lifestyle-related illnesses like diabetes, heart disease and cancer that could mostly be avoided with healthier diets and exercise.

“No longer can the public afford a system that shifts the burden of care for the uninsured onto those who have health insurance or onto the fragile health care infrastructure we have,” said Dr. Charles P. Mouton, professor at Howard University College of Medicine and chairman of the Department of Community and Family Medicine. Instead of accepting the fact that millions of our citizens seek routine medical care through hospital emergency rooms, we need to build a system that promotes health and wellness for all. At the same time, nobody should consider good health as a purely personal matter that is nobody’s business but his or hers. We all have a civic duty to maintain our health as best as we can and not unnecessarily burden society with the consequences of poor lifestyle choices. Only then we can hope to finally achieve a health care system that is just, viable and can be embraced by all.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun.”