In adults with obesity, a single ultra-processed meal produces no significant difference in post-prandial concentrations of ghrelin, leptin, GIP, glucose, insulin, HOMA-IR, energy expenditure, or heart rate variability compared to a nutritionally matched non-processed meal.

When people eat ultra-processed foods, the food is softer and breaks down faster in the mouth, so they chew less. This reduces signals from the mouth and throat to the brain that normally tell the body it's full. Because those signals are weaker, people keep eating longer, but the body still releases the same amounts of hunger and fullness hormones, blood sugar, insulin, and energy-burning signals as it does after eating whole foods with the same calories and nutrients.