Summary
This randomized, tightly controlled NIH study tested whether ultra-processed foods cause people to eat more than unprocessed foods when calories and nutrients are matched. Twenty healthy adults consumed an ultra-processed diet and an unprocessed, whole-food diet for two weeks each in random order, with all meals matched for calories, macronutrients, sugar, sodium, fiber, and energy density, and eaten ad libitum.
Despite identical nutrient profiles, participants consumed about 508 more calories per day on the ultra-processed diet, primarily from carbohydrates and fat, with no difference in protein intake. This excess intake led to measurable weight gain (~0.9 kg) during the ultra-processed phase and equivalent weight loss during the unprocessed phase, with weight change strongly correlated to calorie intake.
The study demonstrates that ultra-processed foods promote passive overeating independent of nutrient content, likely by altering satiety, eating rate, and food structure. The findings suggest that reducing ultra-processed food intake may be a powerful strategy for preventing and treating obesity because these foods drive higher calorie consumption automatically, not simply because they are higher in calories.
PMID: 31105044
PMCID: PMC7946062
DOI: 10.1016/j.cmet.2019.05.008
Abstract
We investigated whether ultra-processed foods affect energy intake in 20 weight-stable adults, aged (mean ± SE) 31.2 ± 1.6 years and BMI = 27 ± 1.5 kg/m2. Subjects were admitted to the NIH Clinical Center and randomized to receive either ultra-processed or unprocessed diets for 2 weeks immediately followed by the alternate diet for 2 weeks. Meals were designed to be matched for presented calories, energy density, macronutrients, sugar, sodium, and fiber. Subjects were instructed to consume as much or as little as desired. Energy intake was greater during the ultra-processed diet (508 ± 106 kcal/day; p = 0.0001), with increased consumption of carbohydrate (280 ± 54 kcal/day; p < 0.0001) and fat (230 ± 53 kcal/day; p = 0.0004), but not protein (-2 ± 12 kcal/day; p = 0.85). Weight changes were highly correlated with energy intake (r = 0.8, p < 0.0001), with participants gaining 0.9 ± 0.3 kg (p = 0.009) during the ultra-processed diet and losing 0.9 ± 0.3 kg (p = 0.007) during the unprocessed diet. Limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.