A Reward Cue

Sweet foods activate the brain's reward system, including dopamine pathways that help teach you to repeat useful or pleasurable behaviors. That is real biology, but it is not the same as saying sugar works exactly like an addictive drug.

The practical problem is simpler: added sugar is cheap, concentrated, and easy to overeat, especially when it is packaged with fat, salt, and constant cues to take another bite.

The trap is learning and tolerance to sweetness. The more often you make foods very sweet, the more normal that level can start to feel. A mildly sweet coffee or yogurt may taste flat next to the sweeter version you trained yourself to expect.

That does not require a drug-style receptor story. It is enough that your reward system, habits, and taste expectations learn from repetition.