Only recently. Here is lopez:
the channels of interstate commerce,
the instrumentalities of interstate commerce, or persons or things in interstate commerce, and
activities that substantially affect or substantially relate to interstate commerce
Looks like health insurance is covered...notice that he did not define commerce...
but there was more from Rehnquist
The Court reasoned that if Congress could regulate something so far removed from commerce, then it could regulate anything, and since the Constitution clearly creates Congress as a body with enumerated powers, this could not be so. Rehnquist concluded:
To uphold the Government's contentions here, we have to pile inference upon inference in a manner that would bid fair to convert congressional authority under the Commerce Clause to a general police power of the sort retained by the States. Admittedly, some of our prior cases have taken long steps down that road, giving great deference to congressional action. The broad language in these opinions has suggested the possibility of additional expansion, but we decline here to proceed any further. To do so would require us to conclude that the Constitution's enumeration of powers does not presuppose something not enumerated, and that there never will be a distinction between what is truly national and what is truly local. This we are unwilling to do."
Now understand that up until Lopez, the commerce clause did not have this type of constraint upon it and was used to regulate all sorts of activities that one would assume is commerce. Fisheries, salamanders, pollution, wages, labor laws, race relations and so on all fell under the commerce clause regulatory powers. In Raich, Scalia even said growing pot for yourself was interstate commerce in support of New Deal type regulations on farmers. Why would 17% of the economy not be subject to federal regulation if the commerce clause allowed you to forbid raw dumping of sewage into a river on the state line?