Adventuring is hungry work.
A normal, sedentary lifestyle runs you around 2000 calories a day. Athletes (which would probably be more akin to adventurers) do around 3800 healthily. In addition to calories, there’s also a idiosyncratic set of nutritional needs per person – vitamins, minerals, and an appropriate balance of protein, carbohydrates, and fats. All of this get usually simplified as ‘you have ten days worth of rations.’ If you want to add some survivalist flavor to your game, here’s some approaches you might decide to use.
First and foremost, starvation should be a risk of all adventurers. Food stores should be under siege, and adventurers should have to make tough decisions between bringing more food or relying on their ability to forage. Starving to death hurts, and even a few days without food greatly impair the ability to operate in a high stress or combat environment.
There’s a limit to how long food can be preserved, and (in general) the more nutritious the food, the quicker it will putrefy. Issues with preservation will also play into food and disease. Moreover, food that is foraged from the wild is difficult for the inexperienced to preserve. All of these issues are lessened somewhat in cold, arid environments and exacerbated by humid, wet environments (which are conducive to the growth of bacteria and fungus).
Attraction of Predators + Danger
In the modern world, nothing attracts bears like campers and their food (besides perhaps garbage pails). Certain food might need to cooked in order to be consumed, but the fire attracts
Food and Disease
In most games, disease is something inflicted upon a character from the outside. But really, ‘disease’ can just as easily come from deficiencies. Classically, sailors were at risk for scurvy due to not getting enough vitamin c, but any number of terrible conditions can be inflicted upon people who aren’t eating a balanced diet. Maybe the adventurers that rely too long on iron rations begin to feel their teeth loosen, experience emotional volatility, or get progressively weaker.
Food Affecting Morale
Finally, gathering around a warm fire and breaking bread; or even just eating food you enjoy can greatly improve morale and group feeling. Without these things, the mood of a group can darken and petty disagreements erupt into full blown conflict. Taking this into consideration can add a lot of verisimilitude and give party a reason to take extra time (and assume extra danger) just to secure something as ‘inconsequential’ as better food.