The Study
Ultra‐processed foods cause weight gain and increased energy intake associated with reduced chewing frequency: A randomized, open‐label, crossover study
This study showed that when 9 guys ate only ultra-processed foods for a week, they ate more and gained weight compared to when they ate regular food. But it doesn't prove that UPFs make everyone gain weight—it just shows what happened in this one small group under strict rules.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
This study gave men two kinds of meals for one week each: one with regular food and one with processed junk food — but both had the same calories and nutrients.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 573 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means even if you think you're eating the same amount of food, processed foods trick your body into eating more and storing fat — and they may even stress your liver.
- 2When eating junk food, they ate 814 more calories a day and gained 1.1 kg, even though they weren't told to eat more.
- 3They also chewed 20% less per calorie, ate faster, and got more salt and less fiber.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Diabetes
Year
2024
Authors
Shoko Hamano, Mika Sawada, Masakazu Aihara, Yoshitaka Sakurai, R. Sekine, S. Usami, Naoto Kubota, Toshimasa Yamauchi
Related Content
Claims (5)
Foods that are highly processed and lack physical structure lead to higher calorie consumption because they require less chewing and reduce the body's natural signals that tell you when you are full.
Young overweight Japanese men who ate ultra-processed foods for one week gained 1.1 kilograms on average and consumed 813.5 more calories per day than when they ate non-ultra-processed foods.
Young overweight men who eat ultra-processed foods consume about 814 more calories per day than when eating unprocessed foods with the same total energy and macronutrient content, due to higher intake of carbohydrates and fats.
Young overweight men who eat ultra-processed foods chew less frequently per calorie than when they eat non-ultra-processed foods, resulting in faster eating and higher total calorie intake due to reduced satiety signals.
Young overweight men who consume ultra-processed foods eat 5 more grams of salt and 34 fewer grams of fiber each day, resulting in higher calorie intake and greater metabolic stress.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.