For breakfast, the prisoners would be given an immitation of coffee or herbal tea.
For lunch, watery soup, and if they were lucky,they might had found a piece of turnip or potato peel.
For dinner, a piece of bread and a small piece of sausage.

This is why hunger was one of the biggest issues in concentration camps. Many died of starvation or illnesses caused by lack of nutrition.

The ones who survived with that little food didnt last long either. If they would get to weak, they would be automatically sent to the gas chambers.