Almost $6000 has been donated to support Dr Fettke and the business Nutrition for Life, owned by he and his wife Belinda, after news of the “caution” was shared on social media on Sunday.

Mrs Fettke said the AHPRA investigation was carried out over 832 days after an anonymous notifier reported Dr Fettke for recommending patients reduce their sugar intake to those of the recommendations of the World Health Organisation.

“The ruling from AHPRA is that he has been cautioned against giving any specific nutrition advice to patients or to speak on nutrition to the public, especially in relation to diabetes management and cancer,” she said.

An AHPRA spokesperson said the agency did not comment on individual cases, and that information on individual cautions were not always made publically available. AHPRA define a caution as a written warning, intended to act as a deterrent so that the practitioner does not repeat the conduct or behaviour.

While there are no official conditions that restrict Dr Fettke’s practice, his wife said their understanding of the “caution” was that he could no longer provide nutritional advice to patients or to the public.

“There is nothing associated with your medical training or education that makes you an expert or authority in the field of nutrition, diabetes or cancer,” the letter to Dr Fettke said. “Even if, in the future, your views on the benefits of the LCHF lifestyle become the accepted best medical practice, this does not change the fundamental fact that you are not suitably trained or educated as a medical practitioner to be providing advice or recommendations on this topic as a medical practitioner.”

Mrs Fettke said not being able to give nutrition advice as an orthopaedic surgeon could compromise Dr Fettke’s patient care.