Hi Harakoni, I'm a modder and I was looking for an answer to this myself. I couldn't find anything, but I did see that you asked the same question on your User page. So I said to myself, that if I figured it out, I'd let you know. Lo and behold, here we are.
I'll give you a high level summary of what I've found. Hunger is calculated as: HungerRate = BaseHungerRateFactor * HungerRateFactor * BackstoryHungerRateFactor * HungerRateMultiplier With the following: BaseHungerRateFactor = RaceBaseHungerRate * LifeStageHungerRateFactor HungerRateFactor = product(Hediffs.HungerRateFactor) + sum(Hediffs.hungerRateFactorOffset)
Eg: A Gourmet (1.5) Human (base 1.6) pawn with a reprocessor stomach (0.75) and a psychic hunger (+0.5) persona weapon sleeping in a bed connected to a sleep accelerator (1.2) will have: 1.6 * (0.75+0.5) * 1.5 * 1.2
So to break down in human terms: HungerRateMultiplier is a global modifier that is taken into account after all other modifiers. These multipliers are added together (though currently the only HungerRateMultiplier in the game is the Sleep Accelerator). Backstory ignores offsets. HungerRateFactorOffset have a huge say in the hunger rate of your pawn and are capable of supercharging or crippling your pawn. HungerRateFactors are multiplicative and as such, get less efficient the more buffs of that type you get.