A move to cover expensive weight-loss drugs for Americans on Medicare and Medicaid may be in the works, but any such program could run into problems with voluntary participation and concerns about expense.

According to the Washington Post, 13 states currently cover the drugs for Medicaid patients, while Medicare prohibits coverage of the drugs used solely for weight loss, but allows for treating indications they are approved for like sleep apnea and heart disease.

The Trump administration is planning an experiment to cover weight loss drugs under Medicare and Medicaid, potentially benefiting millions of Americans struggling with obesity.