Show producers had asked the other contestants if they would object to Diamond participating in the weigh-in after it was revealed that the star had had a gastric band fitted to help her shed the pounds.
However, when one of the teams objected, Diamond decided to leave the show.
Sharon Marshall told The Sun: "Anne annoyed us when she said she'd not been able to get to the gym because of the press outside her house."
Anne was upset by the harsh treatment by the rest of the group for what she felt was a minor infraction. Her spokesperson told The Sun: "Anne joined 'Fit Club' to take part in a programme where everyone receives the support of celebrities and producers alike. Unfortunately the actions by certain contestants have turned this into 'Celebrity Spite Club'.
"In light of the actions of certain contestants she is reviewing whether she can return."