- You won't be as hungry as you think. The heat and the general atmosphere and activities contribute to not wanting to eat a lot for many people. I'm good with one normal meal a day out there, and a few nutritious snacks the rest of the day, plus plenty of water.
- Make sure you're eating foods with salt, because you're sweating out a lot of salt during the daytime heat. The corollary is that salty food generally tastes pretty good out there.
- Make sure you're drinking a lot of water. Allocate a gallon per day per person for drinking water. Extra if you want to use water to shower, of course.
- Fresh vegetables and juicy fruit feels like a luxury by mid-week.
- Eat high-quality, calorie-dense foods for snacks. I like things like nuts and good cheese. Peanut/almond butter is good.
- If you're in a tent, boiling food in bags is a great way to go. Make things like curries or stews or meatballs in sauce ahead of time. They work really well. Dehydrated camping meals can work well too. Google up 'Mountain House' on Amazon, which is well-regarded brand here. All you need for either is a little propane stone to boil water.
- Instant oatmeal works well for breakfasts because, like #6 above, all you need is boiling water.
- Pasta salads with some meat or tofu in them work great for lunches and should last the whole week.
- Soup works well and if you get impatient, you can just eat it cold! (You really will not care as much about food as you think you might.)
- Some Burners swear by squeeze packets of apple sauce or quality baby food. Basically just mashed up fruit and/or veggies. It can be hard to convince your body that you need food out there, but these hit the spot, especially if you keep them cold in a cooler.
- Microwaving if you're in an RV is an option for frozen foods, since you'll have a small freezer and microwave.
- Keep your food cool and pace your meals during the week so the frozen stuff is available at the end, the fresh at the beginning-midweek if applicable.
- Or just drink booze. Whatever. Life's short!
Keeping Cold things Cold
If you're in an RV, just use the fridge and/or freezer. Done.
For everyone else, you'll want a cooler. Obviously, any cooler will keep food colder than it not being in a cooler, but there's a vast difference between coolers. Your cheap grocery store coolers won't keep food/ice cold very long at all, and you'll have to make frequent trips to Arctica (where you can buy ice) to refill the ice in your cooler.
If you want to invest in a great cooler, there are a few brands of cooler that are uniformly high quality and are priced as such. Yeti, Engel, Pelican are three of them. I have a 65 quart Pelican cooler myself, and it is phenomenal at keeping things cold for a long time. At BM 2014, for instance, I left home on Saturday, arrived on playa Sunday afternoon, and didn't get ice until Thursday.
However, other coolers will work too, particularly if you add insulation to them (see tips, below).