Some food also reduce thirst like fruits but very little.Drinks reduce thirst, any kind of driink.During combat you'll get thirsty a little faster.Toxicity level also slows down thirst rising by a lot.if not thirsty you will get additional stamina regen.Being completely thirsty fully negates stamina regeneration!.The less stamina you have, the faster it's gonna rise.Thirst rises the fastest, but is also reduced by drinks the fastest.Some drinks also reduce hunger ( like milk ) but very little.Amount of reducing is shown in the tool tip of every food and depends on food quality.the more toxicity and adrenaline you have, hunger will rise slower there fore drinking potion and being agressive in combat is more rewarding.If fully sated adrenaline will deplete slower, and if hungry faster.if you reach critical levels of hunger vitality will slowly drain.the less vitality you have the faster hunger's gonna grow.Vitality has the biggest effect on the hunger and vica versa.