Elon Musk, the world's richest man and CEO of Tesla, revealed on his social media platform X on Thursday that he is using Eli Lilly's Mounjaro to lose weight.

Musk posted a photo of him dressed as Santa Claus, standing next to a Christmas tree, with the caption "Ozempic Santa."

Ozempic is Novo Nordisk's diabetes drug, which has the same active ingredient, semaglutide, as the company's weight-loss product Wegovy.

Mounjaro, on the other hand, is a diabetes drug from Eli Lilly and has the same active ingredient as the company's weight loss drug Zepbound, which is tirzepatide.

Both semaglutide and tirzepatide are GLP-1 (glucagon-like peptide-1) drugs.

Musk later confirmed in multiple tweets that he was using a drug similar to Ozempic. "Technically, Mounjaro, but that doesn't have the same ring to it."

"High doses of Ozempic made me fart & burp like Barney from the Simpson's," he explained. "Mounjaro seems to have fewer side effects and be more effective."