McDonald's shares slip after downgrade spurred by weight-loss drug popularity

McDonald's shares dropped Tuesday as weight-loss drugs threaten to take a big bite out of the fast food chain's earnings. 

Shares were down by as much as 1.7% Tuesday, after equity analysis firm Redburn Atlantic downgraded the burger giant's stock rating two notches, from buy to sell. 

Changes in Americans' eating habits spurred by the use of the class of drugs known as GLP-1s, which are designed to help regulate users' blood sugar and appetite, pose an underappreciated threat to some food businesses, according to Redburn Atlantic analysts Chris Luyckx and Edward Lewis.