A “self-help” guru convicted of running a cult-like organisation of sex slaves who were branded with his initials was sentenced to 120 years in prison by a New York judge on Tuesday.

The effective life sentence for Keith Raniere, 60, comes after he was found guilty of coercing women into having sex with him as the charismatic leader of Nxivm, a life-coaching group that attracted a coterie of rich and famous devotees.

Followers signed up for $5,000, five-day self-help courses, but some were then financially and sexually exploited and forced to follow a restrictive diet, as Raniere – known as “Vanguard” – exerted control, his six-week trial heard.

He established a faction within the group called DOS, a pyramid structure in which the women were “slaves” and “Grand Master” Raniere sat at the top.

The “slaves” were made to have sex with Raniere, hand over personal information and compromising photos – and some of the women were branded like cattle as other members held them down.

Raniere was convicted in June last year on all seven charges brought against him, including racketeering, sex trafficking, extortion, criminal conspiracy and the sexual exploitation of a 15-year-old girl.

“I was a child. [He] robbed me of my youth,” said the woman during an impact statement at his sentencing hearing.

A total of 15 people – 13 of them women – addressed the Brooklyn court on Tuesday while more than 90 victims wrote letters to Judge Nicholas Garaufis.

Nxivm – pronounced Nexium – proved a huge draw with its promise of self-improvement courses after Raniere founded the organisation in New York state in 1998.

But Raniere, who was arrested in Mexico in 2018, swapped the personal development training courses for sex sessions as the head of a subgroup of up to 20 women – the youngest of whom was the 15-year-old.

The dramatic story has been the subject of two screen adaptations – HBO’s recently released The Vow docu-series and Escaping the Nxivm Cult, a 2019 Lisa Robinson film focused on the testimony of a mother working to save her daughter from the organisation.

Addressing the court on Tuesday, Raniere said he was “deeply sorry” for the “pain and anger” that his victims had expressed but maintained his innocence.

“I’m not remorseful over the charges. Those are not right,” he added.

Five other people were charged in the case, and all of them pleaded guilty.