This can lead to a condition called "ketosis", which can cause bad breath, nausea and a bad taste in the mouth.

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Ketosis is a state in which the body burns its own fat for fuel and can "cause health problems, such as kidney failure, " according to the medical Web site WebMD.

CNN: Mia Farrow ends fast after health concerns

"Ketosis or something like that, " Farrow said.

CNN: Mia Farrow ends fast after health concerns