A documentary series about Demi Lovato shows how brutally controlled the singer’s diet once was, and, as other pop performers attest, it’s control that underpins damaging behaviour

For eight years of her life, Demi Lovato was served a watermelon cake for her birthday. This wasn’t a watermelon-flavoured version of a proper cake with all the good stuff like butter, sugar and flour, but rather an actual watermelon with some icing on top.

The reason for this was that her team at the time were “trying to keep her weight down”, according to Lovato’s best friend Matthew Scott Montgomery, who is interviewed as part of Demi Lovato: Dancing With the Devil, the YouTube documentary series premiering this week. Her team would police what she ate, he says, and those she was with were also required to eat only when Lovato ate, with no snacking outside of meals, in an attempt to “keep her well” and avoid triggering a relapse into the restrictive eating disorders she struggled with as a teenager.