Professor Tim Noakes has been found not guilty of misconduct, a professional conduct committee found on Friday.
The majority of the conduct committee found him not guilty.
Four or five committee members found that it was not proven that Noakes had acted in capacity as a doctor.
And it was not a reasonable inference that he was undermining breast milk.
Noakes - whose book The Real Meal Revolution promotes a low-carbohydrate, high-fat (LCHF) diet - was charged with giving unconventional medical advice via Twitter two years ago after he advised a breastfeeding mother to wean her baby onto LCHF.
The independent committee made its finding following a protracted hearing into a complaint by the former president of the Association for Dietetics in South Africa, Claire Julsing-Strydom.
She had complained about Noakes giving advice relating to his LCHF diet on Twitter to a mother.
The mother's tweet read: "@ProfTimNoakes @SalCreed is LCHF eating ok for breastfeeding mums? Worried about all the dairy + cauliflower = wind for babies?? [sic]"
Noakes advised her to wean her child onto LCHF foods, which he described as "real" foods.
His tweet read: "Baby doesn't eat the dairy and cauliflower. Just very healthy high-fat breast milk. Key is to ween [sic] baby onto LCHF."
He has over 85 000 followers on the social network, on which he regularly shares articles and research supporting the LCHF, or banting, diet.
Earlier in the hearing, which started in 2015, witnesses for the HPCSA said a consultation was required before any advice could be given or diagnosis made.
Julsing-Strydom brought the complaint.
Noakes questioned why Leenstra, who ostensibly could have suffered harm, did not lay the charge. He argued he did not give advice on breastfeeding, but on weaning.
Noakes alleged that Julsing-Strydom's complaint was not centred on breastfeeding, but on the diet he advocates in his book, of which she did not approve.
The HPCSA argues that Noakes gave unconventional and unscientific advice, and was unprofessional in his conduct for dispensing the advice via social media.
Two international witnesses testified in his defence - diet and health researcher Dr Zoe Harcombe from London, and investigative journalist Nina Teicholz from New York, who is the author of The Big Fat Surprise, which "explains the politics, personalities, and history of how we came to believe that dietary fat is bad for health".
Noakes during the hearing argued that his advice was anything but unconventional, quoting research from as far back as the 1800s before the boom in obesity rates.
Noakes said he had personally not made a cent from his banting books and that his sole intention was to educate people to be more healthy.
He and his legal team pointed out there were no studies proving that LCHF diets were harmful, and he had also never told the mother not to breastfeed.
Noakes, listed as the 38th most followed scientist on Twitter at the time, and the 30th most important tweeter on obesity, during the hearing said the future of medicine lies on the Internet and social media, and this is where people will get their information - "in the wisdom of the crowds".
Professor Willie Pienaar, a psychiatrist and part-time bioethicist, during the hearing said that doctors cannot give expert advice without consultation.
He argued that Noakes had the opportunity to refer the mother to a general practitioner, and pointed out that he didn't ask the age or health status of the baby.
He said his main concern was that Noakes had given specialist advice via social media and that consultation was key to giving the correct diagnosis.
Expert witness Professor Este Vorster, a former president of the Nutrition Society of SA, said Noakes could not give convincing evidence that his was the optimal diet for lactating mothers.
Twitter should not be used for medical advice and an assessment should have been conducted, she testified.