What food to take on a 3-4 day long hiking trip?

The dehydrated foods made for camping are generally the tastiest and most weight efficient by far, but if they are too expensive (understandable; they are generally very pricey no matter where you are), there are cheaper alternatives.

There are a wide variety of trail mixes, ranging from the classic GORP ("Good Old Raisins and Peanuts") to much fancier fare. These hold up well in all temperatures, and provide good energy without a lot of weight.

Also consider some staples from the grocery store. In addition to the hardier and more convenient fruits and vegetables (apples last a while, don't require peeling, and aren't terribly heavy; plums, cucumbers and grapes also travel well), there are a number of dehydrated foods available cheaply that make good camp foods. Many fruits are available in dried form, and while high in sugars, they keep exceptionally well, and are very light. Small boxes of dried couscous and rice & bean mixes are great, although they require additional water, and may require small amounts of vegetable oil as well.

For desserts, cookies are light, although they tend to break during hikes. If you don't mind crumbs (they taste the same, after all), they're a good choice for treats. Also the classic S'mores (graham cracker, chocolate bar, and marshmallow melted into a small sandwich over a campfire) is light and fun.

For a treat that will add a little more weight, but may still be well worth it, bring a can of pie filling of the fruit variety of your choice (cherry is my personal favorite, but there are many other options). Over your campfire, pour the fruit filling into a pot, and crumble some graham crackers into the mix. Heat, and spoon yourself some yummy, sticky dessert. IMO it's always good to have at least one can with you, as a can can be a very useful tool for collecting, heating, and drinking water in a pinch.

It is worth noting that many of these ideas rely on having some basic camping cookwear and utensils. If you don't have them, I highly suggest investing in a decent set of light-weight camping cookwear. It adds some weight to your trip, but makes your overall dining options much more flexible, and allows you to abandon some of the heavier food options.

Crispbread, summer sausage and hard cheese. Energy bars without meltable chocolate. Apples, cucumbers. Dextrose tablets.

If you can get a fire going, you might want to bring potatoes, corn, aluminum foil and cans with lentils and similar. For the first day, also ordinary sausages and ordinary bread and bananas

Obviously, water bottles to fill up. Some beverage tablets to enrich the water with minerals and salts.

Peanut butter is good to carry. They can be sold in packets so that you don't have to have a jar and it will be light in the backpack. Peanut butter is a healthy fat and will provide protein to keep you guys going. Peanut butter will go great with any type of fruits that you might bring and crackers also if you can fit them in.

We recently went to Hawaii and brought Justin's peanut butter in packets. Sometimes we ate it plain and others we put it on some honey wheat sticks. This really helped keep us going on our long hikes and gave us energy when we were low.

• Dried starch-type food. In Asian stores you can find cheap "mi tom" or "instant ramen" packs in compact packages. Also take one in the "foam bowl" package type, you will be able to reuse it. About 2-3 packs for a meal. You can eat it just like this, or put it in water you just boiled, if you have. They come with various exciting spices.
• Rusk (hard dry twice-baked bread).
• Dried fruits
• Sugar. In Japan they sell tasty brown sugar in packs of rough bite-size blocks, eat one every time you need energy.

All of this is:

• Resistant to shocks
• Very cheap
• Excellent energy/weight ratio (no water nor fat)
• Good enough to not get too bored after 4 days.

Tested by me during several 4-days hikes, where they really were no stores (and no other human beings for that matter).

This question is difficult to answer, since it depends on the area, circumstances and your general condition. If it is a first time hike, and the conditions are not harsh. I would suggest to go to a local hiking store, where you can buy "astronaut" food. These are packages that weight nothing and still can be very delicious. Furthermore bring along a large amount of energy bars, also to be found in the better hiking store.

But the most important thing to have is sufficient water. Don't underestimate the amount of water you need. If you have enough water in the hiking area, you might consider bringing a filter, or disinfecting tablets. In any case do cook the water you are consuming.

If you consider to hike more often, I can suggest taking a course in finding food in nature.

I make two to three trips to the boundary waters between Minnesota and Ontario every year. And for meats that are canoed or hiked in, I always freeze the first night, (next morning's) meat, and if it's spring or fall, can repeat again the next night, pre planned and the next morning so on and so forth, nature becomes an ice box.

The meats that are carried along for the next couple weeks are salami's, cured cased sausages, pepperoni, summer sausage, salted, cured and heavily smoked side pork and bacon, dried chipped beef. We have tried smoked hard boiled eggs and they do stay. But if the weather is temperate and cool, you can freeze as many eggs as you want, and use them at discretion until you crack one and don't feel easy about it. I've had them last 10 days fresh but results do vary.

The important thing to know, is that if you don't feel safe eating it when you are preparing it, then do not, if you don't have to. This should be treated as supplement food to your forage, fish, and main dry food. There is no completely safe paleo packaway meal for days or weeks. And dry food stuffs should always be a focus of balance if you are trying to stay on the safe side.