When starting adventurers pick out their initial gear it's always fun to see what nifty toys they picked. You can also tell what kind of players you have by hearing the questions, or reading the lists the players present to you. Veteran and neophyte alike however seem to be rather interested in carrying great quantities of rations for food.
A few years ago, for my own reasons that don't need to be discussed here, I was forced to live on the streets for awhile. I'm not talking "ooo, spiffy crazy camping trip" I mean the kind that causes people to only own what they can carry and when you don't know IF you'll ever live with a roof over your head again. Somehow I'd actually managed to get some modern hardtack, some beef jerky, and a small block of cheese.
This is pretty much what you'd expect the average adventurer's rations to look like. By day three, I was willing to kill to eat something that wasn't one of those three things and I felt weaker than I ever had been before.
After about a week of living like this, you DO lose muscle mass, you're often still hungry, but you don't want to eat that stuff b/c doing so is hurting your insides. You end up with one of any number of gastric problems(constipation, horrid gas pains, etc). Thankfully I was able to procure other food sources within the next couple of weeks(it's amazing what skills you can pick up when your life depends on it), and surviving on rations is not something I'd ever want to do again.
After I managed to get things settled and back the way they should be(ie a roof over my head, food that didn't make me sick, and internet!), I began to do some research. The reality is, food rations are never meant to be used long term. It's a means of providing an extra calorie boost to people who went a little further afield than a field kitchen can go. Additionally, I found out that rations generally don't last as long as you think they will, especially if you don't have access to ziplock bags.
What does this mean for campaigns? Well, for starters it means that anyone who isn't some sort of masochist or has a deathwish is actually going to have to plan out their expeditions. For the most part, you would carry a few rations into the wilderness, but not the 6 month supply that some adventurers seem intent on bringing.
It also means that trips into the wilderness are, by necessity, going to be shorter. Unless you're willing to spend one day in every three hunting for game; mouse sized and larger, you're probably not going to be out of the safety of a town or village for more than a 2-3 days tops. Alternately, this means the players are going to be setting up base camps so they can go even further afield, or stay away from the town/village longer.
For DMs, all of this information should be giving you at least 2 additional opportunities for adventuring and role playing incentives. With the weight and cost of food, players are likely going to have to hire porters/buy pack animals which will require them to seek out greater sources of income. It also means that a clever party will likely seek out the food stores when storming the enemy's stronghold(so now the players will actually CARE what's in those cupboards you spent an hour on). While some more experienced players are generally of the opinion that one should never eat the food left by their enemies(especially when you're dealing with such disgusting creatures as orcs and goblins who don't even have words for hygiene), this is where bringing that cleric along really pays off. Detect Poison, Neutralize Poison, and the ever popular Purify Food and Drink can easily turn even the most putrid of goblin food "preparation" into something that can be safely consumed by creatures with weaker systems(just about anything that isn't a goblin or otyugh)