Some starship designs.
There's little information on how much food and water supplies crew get through whilst aboard a ship.
Each stateroom includes four weeks of food and water for one person. Water is mostly recycled, food is assumed to be mostly a proto-paste that can be converted to something edible and nutritious (if not entirely tasty) by the onboard food processors.
Luxury (larger) staterooms tend to have the same quantity of food, it just happens to be higher quality.
Extra supplies can be carried in cargo. Each tonne of cargo can contain 100 weeks of supplies for a single person. This includes suitable packaging to keep it fresh over that period.
Note that this is considerably less than what NASA can squeeze in, but there's less need for efficiency so no attempt has been made to improve it to the same extent.
A ship requires 1 point of power for every 10 tonnes of the ship (i.e., 10% of the ship tonnage). This power covers generic ship systems.
If Power is reduced, then the crew need to select what to switch off.