I can suggest HARP rules (core rulebook pp.86)
Starvation & Thirst In a moderate climate, a character needs the equivalent of approximately a gallon of water and a pound of food each day. For every day that a character goes without food or water, a Stamina Resistance Roll against RR (100) is required. Failure results in a -10 modifier to all actions. Two RRs are required if the character is deprived of both food and water. This means that one day without food or water gives a total modifier of -20. Once a character reaches -100, they will pass out and will be unable to wake, with death arriving 2d10 + Constitution bonus hours later. Magical healing cannot remove these penalties – only the process of eating and drinking can save the character. Once the starving character has obtained food and water, the modifiers will be reduced at a rate of -5 per hour until they are fully gone.