A TV chef known as Paleo Pete has angered health professionals by claiming the caveman diet can cure serious illnesses.
Peter Evans's documentary The Magic Pill touts the diet as a cure for autism, diabetes and even cancer.
But doctors are furious about the claims - which they say are dangerous and not based on evidence.
The paleo (or caveman) diet encourages followers to cut out all grains and focus on meat, fish, vegetables and fruit.
Speaking on a radio program, chef Evans said: "Can people actually heal themselves from chronic illness by taking out grains and dairy and sugar from their diet?
"Yes they can."
But Dr. Michael Gannon, President of the Australian Medical Association, said: "These are dangerous claims and they're unfair on the people facing the battle of their lives.
"The parents of a child with autism face many challenges and the last thing they need are false claims about treatments that are likely to make improvements to their child's wellbeing."
Despite the criticism, Evans is standing by the claims made in the film.