Three Kinds Of Risk

The reward loop is only part of the story. Diets high in added sugar, especially alongside saturated fat and ultra-processed foods, are linked with brain and mood risks in three ways:

• Hippocampus - human studies link high-fat, high-sugar patterns with worse memory and navigation, while animal studies show clearer hippocampal changes.
• BDNF - animal work suggests high-sugar, high-fat diets can lower this learning-support protein, but the human picture is less direct.
• Inflammation and metabolism - excess added sugar can worsen insulin resistance and low-grade inflammation, both tied to poorer mood and cognition.

Some researchers even nickname Alzheimer's type 3 diabetes, suspecting that insulin trouble in the brain may speed cognitive decline. It is still a hypothesis, but a sobering one.