Why is it that a hot slice of pizza or a bag of chips can feel more irresistible than a fresh salad? The answer isn’t just about taste. It’s a mix of brain chemistry, emotions, and clever food engineering. From the dopamine rush we get after biting into something sweet to the comfort of sharing fast food with friends, unhealthy foods are designed to capture both our biology and our hearts. Understanding why we crave them so much can help us enjoy indulgence without letting it control us.
Why our brain crave junk food
From an evolutionary perspective, humans are programmed to seek calorie-dense foods and richly flavoured food for survival. Our ancestors lived in tough and uncertain environments, where food was scarce and survival depended on seeking out energy-dense food. Sweetness meant ripe fruit, a quick source of energy. Fats meant long-term fuel. Back then, cravings pushed humans toward foods that were nutrient-rich. However, in modern days these natural foods have almost completely been replaced by ultra-processed products, packed with refined sugar, excess salt, and unhealthy fats.
The reason we struggle to resist these foods is that they directly target the brain’s pleasure centers. These ultra-processed foods stimulate the dopamine reward pathway, the same circuit activated by addictive substances like cocaine. When you drink a soda or grab a chocolate bar, dopamine is released. You experience a brief lift, but that hit of pleasure strengthens the desire to repeat the behavior. Stress is also involved. When we’re anxious or overwhelmed, we tend to reach for chips, chocolate, or other comfort foods. Stress activates habit circuits in the brain, making cravings harder to resist.
Hormones also play a relevant role. Ghrelin, the hunger hormone, rises when we crave calorie-dense foods, pushing us to seek them out. Once we give in, dopamine is released again, drawing us into a constant loop. Carbohydrate-rich foods can temporarily boost serotonin, the happiness hormone. However, what follows next is a crash that leaves us more anxious or down than before. Leptin, which is the hormone responsible for signaling satiety, can become disrupted by constant exposure to processed foods. This may lead to leptin resistance over time, where the body no longer gets the message to stop eating, causing overeating and weight gain.
Food companies invest heavily engineering irresistibly appealing products. When we crave food, we don’t usually choose an apple or a plate of spinach. Instead, we look for candies, chocolate bars or fries. To achieve that effect, companies analyze every detail: artificial flavors, food dyes, preservatives, the crunch of a chip, the fizz of a soda. Everything is designed to keep us coming back.
The industry isn’t likely to change course, which means the responsibility falls on us as consumers. Small changes can make a difference. Choosing an orange instead of orange juice preserves fiber, slows sugar absorption, and reduces cravings. Staying hydrated also helps, since thirst and hunger signals often overlap. Sometimes, a glass of water can calm down what feels like a food craving. These small but consistent changes create small breaks in the cycle of craving and reward, helping us regain a sense of balance.
