The singer has been seeking advice from Cardiff sushi chef Jacky Tiong, who has been telling her how to prepare her low-fat meals at home.
Toing told Now: "Charlotte first came in a couple of months ago. She said she'd spent too much time and money eating junk food.
"She said to me, 'I guess you can't get healthier than raw fish, rice and seaweed'. She loves pickled salmon, so I told her how to make it herself."
Church is now thought to be getting her life back on track.
A friend added: "Everything is falling into place at the moment. She loves how much weight she's lost and she's hoping the publicity she'll get for her waistline will translate into album sales."
