People overate and gained more weight when given meals with processed ingredients (hydrogenated oils, high-fructose corn syrup, flavoring agents, emulsifiers) compared to people given meals with the same caloric & macronutrient composition that did not contain processed ingredients.

In this small randomized controlled trial, the processed and unprocessed meals had the same amounts of calories, sugars, fiber, fat, and carbohydrates, and participants were free to consume as much as they wanted. Those people given the meals with processed ingredients ate around 500 more calories and gained 2 lbs more than those that did not have the processed ingredients.