Demi Lovato has spoken out against Lady Gaga’s decision to have a vomiting performance artist accompany her at a recent performance.

During her performance of “Swine”, Gaga had Millie Brown on stage who proceeded to vomit coloured liquid over the singer.

An agry Lovato took to Twitter and said: “Sad... As if we didn't have enough people glamorizing eat disorders already. Bottom line, it's not "cool" or "artsy" at all.”

Lovato herself has suffered from bulimia and received treatment for the eating disorder back in 2010.

Lovato proceeded to post several more tweets: "Someone has to come forward and say it and I'll take the heat for it.”

She then tweeted Gaga directly: "@ladygaga you're SO talented," she continued, tweeting the star directly, "if not one of the most talented in our industry PERIOD.

"Dope is INCREDIBLE.. but you don't have to do that"

Gaga has yet to respond to Lovato’s comments.