The blood-sugar / dopamine spike and crash

A fast hit of sugar or refined carbohydrate on an empty stomach drives a steep rise in blood glucose, and that rise is mirrored by a dopamine rise — which is exactly why it feels so good in the moment. The catch is the other side of the curve: the steep climb is paid back with a steep drop that takes blood sugar, brain energy and dopamine below baseline, producing lethargy, yawning, switched-off focus and, a couple of hours later, a fresh craving for the same food that started it. This couples a metabolic mechanism to the ADHD reward system, where easy dopamine is already tempting and steady energy is already hard to hold. The practical levers follow from the shape of the curve: blunt the spike by eating fat, protein and fibre first (they slow sugar absorption like a dam), and prefer many small gentle rises near baseline over one big spike-and-crash. This is a popular-nutrition framing applied to neurodivergent eating rather than a proven ADHD-specific pathway, but the underlying glucose-and-energy dynamics are well established.