Reward system
The brain's reward system uses dopamine to signal: this is worth it, remember it. Sugar, fat and salt trigger it especially strongly.
Ausführlich erklärt
The reward system is a network in the brain that tags behaviour with the messenger substance dopamine: that was good, do it again. Its key hubs are the ventral tegmental area and the nucleus accumbens. In evolutionary terms, it kept us alive: food, warmth, contact and sex were rewarded so that we would repeat them. Energy-rich food was scarce for thousands of years – so the brain rewards sugar and fat particularly strongly.
Today energy is no longer scarce, but the system hasn't changed. Foods that deliver sugar, fat and salt in a combination rarely found in nature – crisps, chocolate bars, soft drinks – stimulate it more strongly than an apple does. Neuroscientists such as Kent Berridge distinguish between “wanting” (dopamine, drive) and “liking” (pleasure). This helps explain why you can empty a whole bag of crisps without really enjoying them after the third handful: the wanting keeps going, while the liking has long since faded.
Importantly, dopamine isn't released only when you eat, but already in anticipation – at the sight of the packet, the smell from the bakery, the thought of finishing work for the day. That's why your surroundings have such a strong effect: what you can see, you want. And that's why substitute rewards that also engage the reward system can help – exercise, music, a chat, a goal ticked off.
Whether ultra-processed foods are addictive in the strict sense is disputed among researchers; what is clear is that they stimulate the same reward circuits particularly strongly. For everyday life, the practical conclusion is enough: make the healthy option visible and easy, and everything else invisible and awkward. And for families: children learn the link “sweets = reward” mainly when parents use them that way – it's better to reward with time together than with gummy bears.