Lady Gaga Credit:

Lady Gaga's Halloween costume left little to the imagination, which isn't too surprising given her flair for theatrics. What was surprising, however, is how quickly the pop star was able to slim down after gaining "25 pounds" in mid-September.

To celebrate the holiday, the 26-year-old created her own ensemble. "I was weed for Halloween," Gaga tweeted Nov. 1. "Best costume ever! It's so fun. Princess High the Cannabis Queen."

Gaga then directed her 30.8 million Twitter followers to her Little Monsters website, where she posted a picture of herself wearing a green wig and matching armbands. The topless singer covered her nipples with green pasties made to look like cannabis leaves. She completed her look with a gold crown.

"Last night was paradise!" the Grammy winner tweeted.

The risque ensemble highlighted the singer's toned abs and thinner arms -- which was Gaga's intention, according to a source.

"She feels great," the source tells Us Weekly of the slimmed-down New Yorker. "She did little things like not drinking coffee or caffeine. . . She doesn't care particularly too much what people think, but she knew she looked good the last few nights and wanted to show it off."

The "Born This Way" chart topper had a strong support system to cheer her on while she toned up. "Whatever weight she's at, she looks phenomenal!" Gaga's trainer, Harley Pasternak, told Us in early October.

In a recent Little Monsters newsletter, Gaga also raved that her boyfriend, Chicago Fire star Taylor Kinney, 31, "prefers me curvier. When I eat and am healthy and not so worried about my looks, I'm happy. Happier than I've ever been. I am not going to go on a psycho-spree because of scrutiny."