Deborah Harrison, 37, and the girl's step-mother, Jennifer Harrison, 40, are accused of banning the girl, 16, from eating.
It is alleged when her step-mother found 34 sweet wrappers stashed in her bedroom, she then hit the girl with a hammer 34 times.
Hull Crown Court heard how the teenager was force-fed seven bowls of porridge when she asked if she could have more sandwiches.
The Harrisons are on trial accused of assault occasioning actual bodily harm.
The pair from Bempton, East Yorkshire deny the charges.
Now 20, the victim told jurors that food such as milk, bread, and potatoes were gradually withdrawn from her until there was nothing she was allowed to eat.
She said: ”Because of that I started to starve.”
She began to hit me as she was getting more and more angry
"All of a sudden you realise there's a whole kitchen full of food and you can't eat it."
The woman said she was forced to keep herself alive on small sweets, pieces of fruit and bread.
In July 2013 she was reportedly caught and her parents decided to "punish her".
She told the court how Jennifer Harrison told her she was "disgusting".
The girl said: "As she was talking she was prodding me to prove a point.
"She began to hit me as she was getting more and more angry."
David Gordon, prosecutor, asked the girl what her mother was doing and she said: "Occasionally she would say things to back it up, like 'disgusting'."
She said: "I did fall down at one point but she (Jennifer) made me get back up again.
"Then she paused and said 'Right, 34 wrappers, 34 hits, and she proceeded to hit me 34 times, counting each one'."
The alleged victim told the court at the age of 14, Jennifer Harrison made her eat seven bowls of porridge, after a request for more sandwiches in her lunchbox.
The woman said: "She made some porridge and I had like seven bowls of porridge. This continued on other days and it got concerning. I couldn't keep it up but they wouldn't let me stop eating."
According to her testimony, the couple made the girl sleep on the floor with dogs, complete "tasks" and perform household tasks.
The girl once took tablets from a medicine cabinet, she said, in a bid to kill herself.
Deborah Harrison and Jennifer Harrison both deny assault occasioning actual bodily harm.
The trial continues.