Food cravings. We all have them, but where do they come from? Well, scientists and food manufacturers use a range of techniques to create a level of addiction in certain foods. We've listed out some of them below.
Dynamic contrast refers to a combination of different sensations in the same food. Foods with dynamic contrast have an edible shell that crunches, followed by something soft or creamy and full of taste-active compounds. This rule applies to a variety of our favourite food structures — the caramelised top of a creme brulee, a slice of pizza, or an Oreo cookie. The brain finds crunching through something like this very novel and thrilling.
Salivation is part of the experience of eating food, and the more a food causes you to salivate, the more it will swim throughout your mouth and cover your taste buds. Basically, foods that promote salivation do a happy little tap dance on your brain to make think it tastes better than ones that don’t.
Rapid food meltdown and vanishing caloric density
Foods that rapidly vanish or 'melt in your mouth' signal to your brain that you’re not eating as much as you actually are. In other words, these foods literally tell your brain that you’re not full, even though you’re eating a lot of calories.
Your brain likes variety. When it comes to food, if you experience the same taste over and over again, you lose a sense of pleasure normally derived from it. In other words, the sensitivity of that specific sensor will decrease over time. This can happen in just minutes.
Junk foods, however, are designed to avoid this sensory specific response. They provide enough taste to be interesting (your brain doesn’t get tired of eating them), but it’s not so stimulating that your sensory response is dulled. This is why you can swallow an entire bag of potato chips and still be ready to eat another. To your brain, the crunch and sensation of eating Doritos is novel and interesting every time.
Junk foods are designed to convince your brain that it is getting nutrition, but to not fill you up. Receptors in your mouth and stomach tell your brain about the mixture of proteins, fats, and carbohydrates in a particular food, and how filling that food is for your body. Junk food provides just enough calories that your brain says “yes, this will give you some energy” but not so many calories that you think “that’s enough, I’m full.” The result is that you crave the food to begin with, but it takes quite some time to feel full from it.
Memories of past eating experiences.
This is where the psychobiology of junk food really works against you. When you eat something tasty (say, a bag of potato chips), your brain registers that feeling. The next time you see that food, smell that food, or even read about that food, your brain starts to trigger the memories and responses that came when you ate it. These memories can actually cause physical responses like salivation and create the “mouth-watering” craving that you get when thinking about your favourite foods.
These factors all combine to make processed food tasty and desirable to our human brains. When you combine the science behind these foods with the incredible prevalence of food (cheap, fast food everywhere), eating healthy can become more of a challenge. But it's worth it.