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:
And also a potential implementation of Profession (Cooking)
And finally, some sample items
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:
* 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.
If you are a Witch, there is a major Hex called ‘Cook People’ which is a great way of getting bonuses for cooking 'good' food. Any Paladins in the group may object, so do your cooking while they're asleep.