Britney Spears has gained 14lbs in just one month.
The Womanizer singer has piled on weight following a break in her world tour and is now under pressure to lose it.
A source said: "She was in tears saying they're calling her fat again. She showed up to a meeting with a latte in her hand and everyone jumped on her.
"Britney's supposed to be eating a diet of fish, chicken and vegetables. When she swaps the healthy stuff for junk, her dad gets worried."
Britney's father, Jamie Spears, who became co-conservator of his daughter's personal and professional life following her breakdown last year, put the Toxic hitmaker on a strict exercise and diet regime as he knows how important it is for her to look good.
However, Britney - who has two sons, Sean, three, and two-year-old Jayden - is struggling to stick to the health plan and regularly indulges in calorific treats.
The source added to Britain's Star magazine: "She does not think about the calories in the food, just that she likes it. She loves greasy food and creamy sweets and hates fruit and vegetables. She still eats a lot of fast food mainly late at night.
"It started as a kid when she hid her habits from her parents. She loves cookies and keeps candy in her travel bags. She hides it or people will be on her case. Her trainers tell her they know she's cheating, but she tells them, 'Mind your own business'."