'DWTS' Gleb Savchenko Claims Ex Made Teen Daughter Take Weight Loss Pills

"Dancing with the Stars" pro Gleb Savchenko is making some disturbing allegations about how his ex-wife treats their teenage daughter ... and he's asking a judge to step in.

According to court docs, obtained by TMZ, Gleb claims his 15-year-old daughter Olivia told him that her mother, Elena Samodanova, made nasty comments about her body, weight, and appearance ... and gave her weight-loss medication without consulting him or getting appropriate medical oversight.

And that's not all ... Gleb says Olivia also told him she was subjected to prolonged periods of silent treatment and had her bedroom door removed as punishment.

Gleb says he's worried about his daughter's physical and emotional well-being, and wants the court to prohibit both parents from subjecting the kids to conduct harmful to their emotional or physical health.

He's not asking to change where the kids primarily live, but he wants the court to ensure his parenting time with Olivia and her younger sister Zlata, who are both living with Elena in Hong Kong, is not shortened or interfered with in any way unless they agree in writing.

As TMZ previously reported ... Gleb and Elena have been locked in a nasty custody battle, with Gleb previously claiming his ex kept their daughters in Hong Kong long after what he says was supposed to be a temporary move.

Things have gotten particularly ugly ... Gleb previously claimed Elena and her fiancé sent Olivia inappropriate messages about him, including sexually explicit remarks. Elena denied those allegations, calling them completely false.