Does Junk Food Make You Crave Junk Food?

Ever noticed that eating Cool Ranch Doritos ends up making you crave more Cool Ranch Doritos? Researchers have observed this behavior in rats, noting that junk food not only makes them fat, but reduces their appetite for good food.

"If the same thing happens in humans, eating junk food may change our responses to signals associated with food rewards," lead researcher Professor Margaret Morris, head of pharmacology from the School of Medical Sciences, said in a press release. "It's like you've just had ice cream for lunch, yet you still go and eat more when you hear the ice cream van come by."

Specifically, the rats lost their taste for novelty. Rats raised on healthy diets tend to avoid flavors in which they've recently indulged in, a trait known to protect against overeating and promote a balanced diet.

When rats were exposed to diets of pie, dumplings, cookies and cake - with 150 percent more calories, however - they continued going back for more of the familiar flavors, even after they returned to a healthy diet.

The junk food diet may create changes to the reward circuits in rats' brains, the researchers said. That circuitry is similar in all mammals, so the implications are likely to be similar in humans.

The study adds to growing research showing how access to junk food may contribute to the worldwide obesity epidemic.

Extreme weather events, financial collapse, political unrest: With today's overabundance of apocalyptic worry, now is a good time to start thinking about what you’ll do if and when the bottom falls out. In a survival situation, shelter, fire and clean drinking water should be your top priorities, said Tom Brown, founder of Tom Brown Jr.'s Tracking, Nature and Wilderness Survival School. And, even though people can survive for up to three weeks without food, Brown said, extreme hunger can make you crazy. So it's worth stocking up on canned foods and other non-perishables. Read on to find out what else you can -- and really shouldn't -- eat when the cans run out.

DO: Pet food People end up eating pet food often enough -- and sales tend to go up during recessions -- that FDA standards require food made for animals to be suitable for humans to eat too, said Cody Lundin, founder and director of the Aboriginal Living Skills School in Prescott, Ariz. In an episode of the Discovery Channel show "Dual Survival", Lundin eats dog food cooked over a campfire -- and while he expresses hope that they'll catch raccoon for breakfast, he lived to tell the tale.

DO: Rodents It's easy to catch rats and other rodents, said Brown, author of "Tom Brown's Guide to City and Suburban Survival." Simply bury a five-gallon bucket in the ground up to its edges. Cover the mouth of the container with sticks and wood scraps, and wait for a startled mouse or chipmunk to scramble under the jumbled objects. The animal will fall right into your trap. Next, burn the hair off your prey, skin them, gut them and throw them into a stew pot with water and any grains, vegetables or flour you might have on hand. "Don't even bother filleting them or getting rid of the bones," Brown said. "Bone marrow is high in nutrition and protein."

DON'T: Leather During their infamous struggle against starvation, the Donner Party ate a wide variety of unappetizing objects, including leather, which is made from animal hides. Long ago, people used the tannins in oak tree bark to turn animal skins into leather, making it a safe food item. But modern leather products are tanned with chemicals that are surely poisonous, said Lundin, author of "When All Hell Breaks Loose: Stuff You Need to Survive When Disaster Strikes." Your belts may look as good as fruit roll-ups when you're really hungry. But it's best to leave them in the closet.

DO: Bugs Grasshoppers, cockroaches, ants, tarantulas: Virtually all insects are edible. Just make sure to cook them well enough to kill the wide variety of diseases they can carry, Brown said. You can even eat bees and scorpions as long as you remove their stingers first. One easy way to catch insects is to fill a sink with a little water and some food crumbs. Hungry bugs will go for the bait and either drown or get stuck in the tub. Ounce for ounce, Brown added, insects have up to four times more usable protein than other animals. Instead of a pound of beef, a quarter-pound grasshopper burger will do the same job.

DO: Weeds "Food plants grow everywhere," said John Kallas, director of Wild Food Adventures, an educational company, and author of "Edible Wild Plants: Wild Foods from Dirt to Plate." "All you need to do is go out in your backyard." You also need to build up some detailed knowledge about botany before all hell breaks loose because eating the wrong plants or the wrong parts of plants can kill you. Common vitamin-rich weeds include wild spinach, cattails, field mustard, garlic mustard, nipplewort and dandelions. No matter how hungry you are, Kallas warned, only eat a little amount of any one kind of vegetation at a time. "Dandelions have some vital chemicals that are great for you in small amounts, but too much will give diarrhea," he said. "That's what you don't want in a survival situation."

DON'T: Cardboard and Paper Cardboard boxes may seem appealing because they contain cellulose from wood pulp, which is used as a thickener, stabilizer and source of fiber in a variety of food products. And along with paper, cardboard can counter hunger pains by taking up space. But people cannot adequately digest the cellulose in cardboard and paper, Brown said. Also, many of these products are treated with chemicals that can be toxic.

DO: Acorns Like any nut, acorns can be delicious and filling, but you can't just pop them in your mouth like cashews. To make acorns edible, Brown advised, first take them out of their husks. Next, drop them in a pot of just-boiled water and let them steep for a couple hours. Drain and repeat this process two to four times until all of the bitter tannic acid is gone. At last, you can eat the acorns plain. You can roast them. Or you can grind them into flour that will accentuate your rodent stew. Play the "Dual Survival" challenge, featuring survival experts Cody Lundin and Dave Canterbury.