Millions of Americans with obesity would be eligible to have popular weight-loss drugs like Wegovy or Ozempic covered by Medicare or Medicaid under a new rule the Biden administration proposed on Tuesday morning.

The costly proposal from the US Department of Health and Human Services immediately sets the stage for a showdown between the powerful pharmaceutical industry and Robert F. Kennedy Jr., an outspoken opponent of the weight-loss drugs who, as President-elect Donald Trump’s nominee to lead the agency, could block the measure.

While the rule would give millions of people access to weekly injectables that have helped people shed pounds so quickly that some have labelled them miracle drugs, it would cost taxpayers as much as US$35 billion over the next decade.

“It's a good day for anyone who suffers from obesity,” US Health and Human Services Secretary Xavier Becerra told The Associated Press in an interview. “It's a game changer for Americans who can't afford these drugs otherwise.”

The rule would not be finalised until January, days after Trump takes office. A bipartisan coalition of congressional members has lobbied for the drugs to be covered by Medicare, saying it could save the government from spending billions of dollars on treating chronic ailments that stem from obesity. While it's unclear where Trump himself stands on coverage of the weight-loss drugs, his allies and Cabinet picks who have vowed to cut government spending could balk at the upfront price tag.

Under the proposal, only those who are considered obese — someone who has a body mass index of 30 or higher — would qualify for coverage. Some people may already get coverage of the drugs through Medicare or Medicaid, if they have diabetes or are at risk for stroke or heart disease.

Becerra estimated that an additional 3.5 million people on Medicare and 4 million on Medicaid could qualify for coverage of the drugs. But research suggests far more people might qualify, with the Centers for Medicare and Medicaid Services estimating roughly 28 million people on Medicaid are considered obese. (AP)