I have designed a character to be able to cook just about anything and make it taste great. This was done mainly for RP purposes but I was curious if there is any system that adds benefits for eating fresh good food. Maybe something like a moral bonus. I am aware of the racial trail rations and might use those without the racial limits if my DM approves.
Like the other answer says, there's no system for this in the pathfinder rules. So here are a few house rules you could use. I would start by inverting the rules for starvation and thirst.
As you get dehydrated, you make successive constitution checks and start taking non-lethal, and then lethal damage every hour. Further, characters who are starving or dehydrated become fatigued. So, being well-fed should invert these effects in some way.
Here's an example status effect I've come up with that could implement this:
A nourished character can run as if she possessed the Run feat, and is granted a +1 circumstance bonus to Strength and Dexterity based checks, as well as a +4 circumstance bonus vs effects that cause fatigue or exhaustion. Becoming fatigued or doing anything that would cause fatigue removes this condition. Otherwise, it fades after one hour.
And also a potential implementation of Profession (Cooking)
You are skilled at preparing exceptionally nourishing meals.
Check: Preparing a meal has a DC of 10 (for a decent meal), 20 (good meal), 30 (extraordinary meal), or 40 (legendary meal). You need ingredients, and a suitable kitchen or equivalent work space. Without a proper kitchen, you take -4 on your cooking check. Cooking without ingredients is impossible.
Decent Meal: Pretty standard fare. A decent meal grants the nourished condition
Good Meal: A good meal, the kind you could expect to find in a particularly expensive restaurant or luxurious inn. In addition to the effects of the nourished condition, a good meal grants a +1 circumstance bonus on fort saves for the condition's duration.
Extraordinary Meal: An incredible meal, the like of which most people will experience only rarely, unless they are quite wealthy. In addition to the effects of a good meal, an extraordinary meal grants 1d8 temporary hit points.
Legendary Meal: A meal of legendary quality. As word gets around of your skill, kings will fight to have you in their kitchens, and beings from other planes will seek you out to experience your masterful creations. A legendary meal grants the nourished condition, as well as a +2 circumstance bonus to all saves, and d8 + (Cook's HD) temporary hit points. Such a meal is so good that creatures who taste it can't bear the thought of dying without tasting it again.
Action: Preparing a meal takes one hour, although a particularly intricate or important meal may take longer, at the GM's discretion.
Try Again: Yes, but every time you prepare a meal any ingredients used are consumed.
And finally, some sample items
Basic Ingredients: The bare necessities required to create a meal. Price: 1s. Weight: 1/4 lbs.
Extravagant Ingredients: Very extravagant ingredients. Grant a +2 circumstance bonus to a Profession (Cooking) check made to create a meal. Price: 15g. Weight: 1/4 lbs.
Legendary Ingredients: Incredibly hard to find ingredients, of legendary quality. Grant a +5 circumstance bonus to a Profession (Cooking) check made to create a meal. Price: 500g. Weight: 1/4 lbs.
Cooking Kit: Basic tools required to cook a meal. Price: 5g. Weight: 5 lbs.
Kitchen: This kitchen is used for cooking, and provides a +2 circumstance bonus on Profession (Cooking) checks. It does not provide any ingredients. Without this kitchen, a character with the Profession (Cooking) skill is assumed to have enough tools to use the skill but not enough to get the +2 bonus that the kitchen provides. Price: 200g. Weight: 40 lbs.
There's nothing in Pathfinder RAW about this. However, in 3.5 there were optional rules on Upkeep (DMG p.130) that we used a variant of in Living Greyhawk:
The GP required to support PCs between adventures is called upkeep.
For 12 GP per TU* your PC gets adventurer’s standard upkeep. This pays for common room and board, replenishes rations, mends clothing and equipment, refills healing and disguise kits, restocks up to twenty normal steel arrows and bolts, and heals hit point and temporary ability damage between adventures.
You may also pay more GP to live better than the average adventurer. For 50 GP per TU, rich upkeep gives the same 5 benefits as standard upkeep and a +2 Circumstance bonus on Bluff, Diplomacy, Gather Information, Intimidate, Perform, Profession, and Sense Motive checks when your GM determines that your increased social status would grant you a benefit. For 100 GP per TU, luxury upkeep increases this bonus to +4.
You may choose not to pay for your PC’s upkeep for an adventure. If you do so, the PC retains any damage into the next adventure and does not gain any of the benefits of standard upkeep. The PC may gain other penalties or benefits at the discretion of your GM. At the beginning of the adventure, if your PC possesses at least five ranks in Survival and succeed on a DC 20 Survival check, he gains the benefits for standard upkeep. He may still gain penalties or benefits at the discretion of your GM. If you fail this check, you may not then choose to pay for upkeep for that adventure.
* Time Unit: Abstraction of time spent not adventuring, about 1 week.
What I'd do is use some variant of these rules and let your Cooking skill contribute $$ towards these - if you have a Profession: Cooking +10 then you are basically producing an excess 10 gp/week to help defray these costs - so you could put in 40-50 gp in a month to having a higher level lifestyle.
In fact, it would be pretty easy to integrate that into the Downtime rules in Pathfinder that otherwise detail life in downtime and have your cooking generate capital. They whiffed on the Upkeep section of the rules, which basically say "uh, nothing," but you could block it in there easily enough.