Is it permissible for a worker at a shelter for the homeless and needy to eat from their food, given that his financial situation is unstable and he works 8 hours a day?

If the owner of the food grants permission to eat from it, there is no problem. However, if they do not grant permission, it is not permissible to eat. Eating is restricted to those registered with them and residing in the shelter, not generally. If, however, the food is going to be thrown away, there is no harm in eating from it, as benefiting from it is better than discarding it. Leaving it in this case is a waste of money, and Islamic law prohibits squandering wealth. The permissibility for a needy passerby to eat from an orchard without the owner's permission has been indicated, and a needy person eating food that would otherwise be discarded is even more permissible.