The 'Heart Attack' hitmaker, who has battled bulimia in the past, took to Twitter last night (14.03.14) to vent her frustration after the 27-year-old singer performed 'Swine' at the South by Southwest festival in Texas, which involved vomiting artist Millie Brown.
Demi tweeted: ''Sad... As if we didn't have enough people glamorizing eat disorders already. Bottom line, it's not ''cool'' or ''artsy'' at all.
''Would you let someone bring a needle and shoot up on you? Addiction is addiction. (sic)''.
However, the 21-year-old singer was forced to defend herself after her honest comments didn't go down well with her fans.
She retaliated: ''It's not ''shade'' and it's not ''hate''. But someone has to come forward and say it and I'll take the heat for it. (sic)''.
Demi then reached out to Lady Gaga directly, writing: ''@ladygaga you're SO talented, if not one of the most talented in our industry PERIOD. Dope is INCREDIBLE.. but you don't have to do that (sic)''.
Meanwhile, Lady Gaga - who has also struggled with body image in the past - said yesterday she fears she had got ''really fat'' during her stay in Austin, Texas.
Millie, who has worked with Lady Gaga before, performs her stunt by drinking coloured milk before sticking her fingers down her throat and vomiting the liquid back up.
The 1969 session, including the only known recording of 'Sunshine Woman' by the band, will be included on a re-issue of 'The Complete BBC Sessions'...
The 55 year old actor joined Chris Martin and co. on stage in New Jersey to perform 'Earth Angel' and 'Johnny B. Goode'.
Bjork Digital comes to London's Somerset House in September, along with a single live show at the Royal Albert Hall.
Kim Kardashian released an audio excerpt from a phone call between Kanye and Taylor Swift over the lyrics of 'Famous' - but if it was recorded...
There's very much a strength of conviction in remaining what you were, but arguably more so in becoming what you want to be.
The BBC drama starring Aidan Turner returns to BBC One on September 4th.
Guns N' Roses were detained at the Canadian border last week for gun possession but they're adamant the weapon didn't belong to them.