The 21-year-old boybander took to Twitter to write about a yummy Bootea drink he had this week (according to their website, the smoothies can help users "lose weight gradually").
"Had an amazing @BooteaUK smoothie from Bootea.com this morning #booteashake," Tomlinson tweeted the other day, angering users who thought he was promoting the weight loss product to his almost 14 million fans.
By the time Tomlinson deleted the tweet, it already had over 10,000 retweets and over 14,500 favorites.
A rep for the 1D singer explained the mistake to E! News in a statement. "Louis tweeted about the drink as he had one this morning and enjoyed it," the rep said. "However, he did not realize they are associated with weight loss, and would never endorse weight loss products."
Meanwhile, the smoothie in question (which retails for 34.99 pound) is currently listed as sold out on the Bootea website. "Currently out of stock. Please sign up to our mailing list to find out when Bootea Shake is stocked up," reads the message.
—Reporting by Marcus Mulick