Food is party fuel!

It is, of course, generally advisable that you eat
healthy, and specifically recommended for a situation like this that has a tendency to be a high-energy, high-demand experience.

Here's some basic nutrition info:

Macronutrients are nutrients you need alot of. Protein, carbohydrates, fats and fibre are all macronutrients.

Complete Protein

There are 20 amino acids that the body uses to construct proteins. 8 of these are essential amino acids. Not all foods contain all the necessary amino acids. Here are some cheap and plentiful combinations of foods which deliver complete protein conveniently at parties:

Hemp seed nuts contain one of the best complete proteins of any plant source (though not the highest levels), and can be incorporated easily into a variety of types of foods, included baked goods and granolas. They have a soft texture and a nutty-almondy taste, and can be thrown on top of almost any meal.

Soy beans, chick peas and lentils are also excellent sources of large amounts of protein, but are not quite complete, and should ideally be mixed with a variety of beans in your diet (whether at the same time or not). Canned and dried beans/pulses make these particularly easy to bring and keep in quantity.

Meats and other animal products have a tendency to be complete protein, hence it being successful in becoming the flesh of the animal in the first place. There are, however, very particular, difficult and crucial steps that must be taken to properly preserve any animal products that you bring up, as conventional refrigeration is not possible, ice will melt by the end of the weekend, and it will almost definitely get hot as hell.

Proteins take a lot out of you to break down and absorb, and must be eaten as part of a complete meal if you intend to stay on-the-go and want your energy levels up.

Essential Fatty Acids

Carbohydrates (such as starches) are energy-storing molecules. There are two types, simple and complex. Simple carbohydrates - basically, sugars - store (and thus provide upon eating) quick-acting, short-lived energy bursts. Anything authentically sweet provides these, and they are important to have in some amount to keep your energy level going. Too much sugar is bad for you in more reasons than is worth listing, of course, so you should be getting your sugar from vitamin-laden fruits and snack bars/mixes rather than from candy, pop, or any other such crap. Sugar is also dehydrating, so keep that in mind 'round high noon (and perhaps around 2 am too).

Complex carbohydrates - what are normally meant by 'carbs' - store long-lasting but slow-acting amounts of energy, and provide the underlying stability to your energy level and sustain you throughout the whole of the day/night. Potatoes are a classic example, along
with breads, cereals, rice and pasta. Eating any of these, especially in quantity, will typically have the effect of knocking you on your ass for a bit while your body consumes energy to digest and absorb the food, but will then start to work later on and last for hours.

It is vital that you get both types of carbohydrates. Consuming only sweet foods when hungry may give you the impression that it's sustaining you, but will inevitably lead to a pattern of peaks and crashes in your energy level. Consuming no sweet foods will likely end up with you taking a few too many naps.

Fibre

When it comes time to poop, you'll probably want to be able to do so quickly and properly, especially in the middle of the woods...

Fibre is similar to complex carbohydrates in that it is a complex form of plant energy storage. However, due to the nature of the molecule, human beings are unable to break down most types of fibre (known as insoluble fibre), and will not get any increase in energy from consuming it. In fact, it will take some energy to get it through your digestive system, so you need to eat it as part of a complete meal if you don't want that
drain.

The key thing with fibre is that it passes through the gut helping other food and waste products move through the gut more easily, preventing constipation and other excrement-related unpleasantness. There are some types of fibre which provide direct nutritional value, as they can be digested, and these are known as soluble fibre.

Particularly good sources of soluble fibre include oats and pulses such as beans and lentils, and these will regulate blood sugar levels and keep them from skyrocketing or plummeting too much. They also seem to clear up cholesterol levels a bit, so if you dig on animal-based foods, you'd be well advised to make them a general staple of your diet. You also need complex carbs, the right balance of oils, vitamins and minerals and plenty of fibre plenty of veggies.

Good Foods to Bring:

Quinoa - complete protein all on its own
Sprouts - Alfalfa sprouts, quinoa sprouts, onion sprouts - bring a wide variety
Nuts and seeds - lots of protein and essential fatty acids
Granola - tasty snack and contains complex carbs, fibre (to help the shits)
Lentils - great in big pots of soup - perfect for festivals
Coconut milk - great source of fatty boombatty
Avocados - also an excellent source of great fats.
Fruit - preserved, such as dried, may be easier to deal with than fresh, but fresh are so delish and would probably be fine tied up a tree rather than sweating in a tent.
Bread - part of a complete camp meal, but should be stored properly.
Noodles/Rice - will provide an underlying "base" to your meals, both in terms of eating them and digesting them, and can be easily brought and stored

Storing Foods

It is important that any fresh food you bring be stored properly. Canned and dried goods will survive days, weeks, months, years without problems, but fresh food can go from good to bad in a matter of hours under unfavourable conditions.

Any high-water food, such as fruits and mushrooms, should be stored in paper bags and not kept anywhere that humidity will be trapped. If fruits and mushrooms are kept in closed plastic bags in closed plastic tents or sitting in a sealed car, they will "sweat out" and progressively turn themselves to a nasty gooey mush.
Heat and humidity will accelerate the breakdown of fresh foods, and should be avoided to as much of an extent as is possible.

For some reason, not many animals tend to come 'round the stages, but insects will still do a great job of getting all up in your food, provided the opportunity.

Community Kitchen
Set up a communal eating/cooking area with your friends & neighbours. Sharing meals is a great way to celebrate mealtime, and a good way to get all the proper nutrition. The more you cook at once, the more easy it is to make the meal healthy, and everyone would probably rather have those amongst them with cooking expertise prepare a big hearty meal than each individually eat soggy cereal out of their shoe.