London: Cheryl Cole has been told to change her diet, which reportedly includes cola and sweets, and reduce her hectic work schedule as she recovers from malaria.
Doctors believe the 27-year-old star has found it harder to get better because her immune system is extremely weak, Daily Mail online reported.
She appeared to have lost weight during a music tour and X Factor auditions before collapsing at a photo shoot last week with the tropical disease.
An X Factor source said, "Sometimes Cheryl would find it hard to find time to have a snack during the day."
"At times, Cheryl has been so busy that the best she could manage to have is sweets and Coke to give her an energy boost," the source added.
Even her close friend, designer Julien MacDonald, added, "Every time I`m with her she`s always got a Mars bar, or she`s drinking a full-fat Coke. And I say `How do you keep so thin, Cheryl?` and she goes `I`m naturally thin`."
The singer has now been forced to pull out of the X Factor boot camp round of auditions later this month, as well as an appearance at V Festival next month.
X-Factor boss Simon Cowell last night said he would ensure that Cheryl did not rush back to work.
"She`s doing OK. I got a text today - she`s doing much better. I think she is keen to get back to work. I just want to make sure she doesn`t rush back too early. We`re going to have a conversation about that," Cowell said.
Cheryl collapsed at a photo shoot last week, before being admitted to hospital where she was diagnosed with malaria, which followed a recent holiday to Tanzania with her friend, dancer Derek Hough.