Marilyn Pauline Bodnar last August pleaded guilty to aiding and abetting the mum, who cannot be named for legal reasons, in failing to provide for the boy in 2015.
The 62-year-old was sentenced in the NSW District Court on Thursday to a maximum 14-month prison term, but she’ll be eligible for parole in November.
Judge Peter Berman handed down a seven-month non-parole period for the “well-intentioned but seriously misguided advice” that “almost led to that child’s death”.
In May 2015, the infant was admitted to Westmead Hospital in a critical condition with severe malnourishment and developmental issues.
"Had he not presented to hospital he could have died within a number of days," Judge Berman said.
The baby weighed just 6.4 kilograms, was emaciated and severely dehydrated, had sunken eyes, dangerously low sodium levels and flexed hands and feet.
In six weeks the mum had lost 11 kilograms and her baby lost 1.6kg.
"Ms Bodnar was aware of this weight loss but assured the mother that this was normal and that (her son) was fat and needed to lose weight," Judge Berman said.
Bodnar must have seemed like a "godsend" to the mother for claiming she could cure her child's eczema by shunning conventional medical treatments, he said.
The former nurse recommended a raw food diet and eventually water only for the woman, who was exclusively breastfeeding the infant.
Doctors assessed the then eight-month-old's development as being equivalent to that of a three-month old.
Judge Berman slammed Bodnar's "gross recklessness" towards the defenceless and vulnerable child, adding it's still unknown whether the now three-year-old will suffer long-term developmental delay.
Crown prosecutor Tony McCarthy said Bodnar ignored the boy's weight-loss warning signs due to a "blind allegiance" to her alternative medicine ideology.
Bodnar deeply regretted her actions and vowed to never work with children again, her defence team said.
Lawyer Rick Mitry said the Leppington naturopath was paraded in front of media cameras by police during her July 2015 arrest and had since been "trolled and bullied on social media".
"She feels crushed. She has been punished," he said.
The mother, a university-trained midwife at a Sydney hospital, pleaded guilty in 2016 to failing to provide for her baby and was given a 14-month good behaviour bond after agreeing to give evidence against Bodnar at her then-expected trial.
Bodnar had a grievous bodily harm charge dropped last August following her own guilty plea, for which she received a discount.
The maximum penalty for Bodnar's crime is a five-year jail term, but Judge Berman noted she had no relevant prior convictions and was unlikely to commit a similar offence again.