An Italian father who forced his teenage daughters to ski competitively and eat a macrobiotic diet because he was concerned they were too fat has been found guilty of abuse and sentenced to nine months in prison.

The unusual case in Turin may set a precedent in how Italian courts define psychological abuse of children. There are no similar cases of abuse on record.

The case started in 2011 when the two teenage girls – one is now an adult – complained to their mother that “Daddy treats us badly” and said they no longer wanted to visit their father. The parents are separated.

The 53-year-old father, who has not been named in press reports but has been described as a wealthy individual, has said he became worried about his daughters’ health when he saw pictures of them on Facebook. He said he encouraged them to ski and to eat a macrobiotic diet, avoiding processed and otherwise refined foods, out of a normal level of parental concern.

But the mother of the teenagers and the prosecutor in the case painted a different picture, of constant pressure and taunting by the father of his daughters.

The sentence for mistreating the girls and causing psychological trauma was a month short of the punishment sought by the prosecutor. The father has said he will appeal against the verdict.

Experts say children subjected to psychological abuse sometimes face the same mental health challenges as children who are sexually or physically abused and can suffer from anxiety, depression, low self-esteem and substance abuse.