Small Trial Finds Ultra-Processing Alone Did Not Change Short-Term Satiety

The study was a randomized crossover trial, published in Appetite in 2026. Crossover means each person took part in every condition, so each served as their own comparison. It included 19 adults (9 women), with an average age of 22 and an average body mass index of 23.5. That is a small group of young people, so the results should be read with care.

Earlier research has found that people eat more of ultra-processed foods when they can eat freely. One idea is that energy density explains this. Energy density is the number of calories in each gram of food. Foods that are low in water and high in fat or sugar tend to be dense. But in many past studies, processing and energy density have been tangled together. This trial tried to separate them.

Each person completed different one-day conditions. On each day they ate a fixed breakfast and lunch. These meals either had no ultra-processed food or got at least 80% of their energy from it. They were also either low in energy density (1.2 kcal per gram or less) or high (2.0 kcal per gram or more). In the evening, they could eat as much as they wanted from the same dinner (1.7 kcal per gram, 20% ultra-processed). Researchers compared the amount eaten with a control day. They also asked people to rate hunger and fullness 15 times a day on visual scales.

The main result was a null one. Neither processing nor energy density had a significant effect on dinner intake. The ultra-processed meals were linked to 24.5 fewer calories at dinner (95% confidence interval: 87 fewer to 38 more). The high-density meals were linked to 41.6 fewer calories (104 fewer to 20.9 more). Both ranges include zero, and neither is clearly different from no effect. The authors also found no interaction, meaning processing did not change how energy density worked.

Appetite ratings did shift with energy density. Compared with low-density meals, high-density meals led to slightly higher hunger (3.61 mm on the rating scale), satisfaction (2.8 mm) and capacity to eat (2.6 mm). They also led to lower fullness (5.3 mm lower). Capacity to eat stayed a little higher after dinner on high-density days (3.31 mm).

The authors concluded that food processing did not affect short-term satiety. They wrote that acute differences in energy density produced small changes in subjective appetite without affecting later energy intake.

For people thinking about appetite, the practical point is modest. The 'ultraprocessed' label may not be the only thing that matters. How many calories are packed into each bite may matter too. This trial cannot say that, though. It did not test it directly over time or in people managing their weight.

The limits are real. The trial was small, with 19 young adults. It measured one day of eating and one dinner. Wide confidence intervals mean a real effect could have been missed. The results say nothing about long-term weight or health.

Larger and longer trials that separate processing from energy density will show whether these findings hold over weeks of normal eating.

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