The eating rate of ultra-processed foods can be reliably manipulated by altering food texture (hard/chewy versus soft/lubricating) without changing nutrient composition, and this manipulation can be measured with high precision using video-based behavioral annotation.

Harder or chewier foods require more chewing and take longer to swallow, which keeps food in the mouth longer. This longer contact time stimulates nerves in the mouth and throat more intensely, sending stronger signals to the brain that the body is full. These signals slow down how fast a person eats and make them feel satisfied sooner, so they eat less. Softer or smoother foods go down quickly, so the brain doesn't get the full signal until later, leading to faster eating and more food consumed.