A mother who left her daughter to die from starvation has had her life sentence quashed, with the appeal court finding the case was not in the worst category of offences.

In the Court of Criminal Appeal on Friday, her sentence was reduced to at least 30 years, with a maximum term of 40 years.

"In our opinion it cannot be said that the present case is within the worst case category, nor that the level of culpability was so extreme that the community interest can only be met by the imposition of a life sentence," Justices Peter Hall and David Davies said in their judgment.

Justice Peter McClellan did not agree with their view, saying he was not persuaded the sentencing judge's decision was "wrong or that the sentence is manifestly excessive".

The seven-year-old, who became known by her middle name, Ebony, deteriorated from a chubby, healthy child to die in the bedroom of her Hawks Nest home in November 2007, weighing just nine kilograms.