So You Want to Overturn Obamacare. Here Are Some Things That Would Be Headaches.

Under Obamacare, a new office can test strategies for how to pay for health services, a provision meant to improve health care quality and efficiency. Many such experiments have been started by the Center for Medicare and Medicaid Innovation, including programs that pay hospitals a lump sum for joint replacement care and one that pays the Y.M.C.A. for a course that appears to lower diabetes risk.

Some of these programs are small, voluntary pilots. Others have been made permanent and expanded nationwide. The office, its employees and all of these programs would lose their authorization.

Some represent Obama administration priorities, but the Trump administration has begun several of its own innovation center projects, including one that may link Medicare’s payment for certain drugs to prices from an international index, an administration priority.

The law also changed several Medicare payment formulas, in many cases reducing the amounts paid to hospitals. Those changes have been wound into regulations and are built into the business models of many health care providers, so rolling them back would not be simple. These changes also helped extend the life of the Medicare Hospital Insurance Trust Fund. Without them, Medicare would be likely to lose several years of fiscal solvency.

The law required chain restaurants to publish calorie counts on their menus. The restaurant industry disliked the rule, and the labels would most likely disappear from many restaurants if the requirement were erased. But the industry has already put considerable resources into adding the calorie information to the menus.

This provision, a longtime priority of Senator Chuck Grassley of Iowa, requires pharmaceutical companies to disclose gifts and payments to physicians.

The health law reduced the so-called doughnut hole in Medicare drug plans, a gap in which drug plans don’t pay for patients’ medications once they reach a certain total cost. This would mean increased drug costs for many people using Medicare.

Obamacare included benefits for breastfeeding mothers, including insurance coverage for breast pumps and a requirement that many employers provide a room for mothers to express milk. If Obamacare were invalidated, the thousands of employers who have changed offices and policies could drop those benefits, but would presumably risk complaints from workers.