"Sad... As if we didn't have enough people glamorizing eating disorders already. Bottom line, it's not 'cool' or 'artsy' at all," Lovato tweeted in response to the performance.
Lady Gaga, meanwhile, has consistently defended what went down on stage as art—and nothing but art.
"I have struggled with an eating disorder for over 10 years and I take that very seriously, I take the struggle of others very seriously," Gaga told E! News Friday.
"I am very supportive of Demi's struggle and her recovery as well as the recovery of anyone who is suffering from that," she continued. "But this performance had absolutely nothing to do with any eating disorder, and we never intended for it to be taken that way.
"I'm really proud of the performance and really stand by the message of rage and pain that we were trying to express in that moment."
And yet the 27-year-old pop superstar certainly doesn't seem to be feeling much rage or pain these days.
"I am in a really good place and I'm really, really happy," Gaga said, professing herself to be a lover of meditation, yoga and good old fashioned "rock 'n' roll and whiskey."
"I'd probably say my truest vice is my friends. I love painting, so we hang around, we paint," she said. "And I think your friends are important. Constantly staying positive and enjoying life with other people, it's wonderful."
Some people more than others, of course.
Watch the clip to hear Gaga's key to happiness with longtime boyfriend Taylor Kinneyand don't miss her on E! News at 7 p.m. & 11:30 p.m.