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What Causes What
MECHANISM+ INCREASES

Ultra-processed food intake → Insulin resistance (HOMA-IR)

Higher Ultra-processed food intake increases Insulin resistance (HOMA-IR).

In Hall's ward trial and Hamano's Tokyo crossover, ultra-processed menus matched for presented calories raised ad-lib intake and weight; Chen's US cohorts associate the same food class with later type 2 diabetes, not with measured HOMA-IR.

Randomized trial · Moderate · N=20

Supported by an experiment or a tightly identified design. Read the caveats.

Mechanism

Hall and colleagues randomized twenty adults to ultra-processed versus unprocessed menus matched on presented calories and macros. People ate more on the ultra-processed diet and gained weight. Energy surplus and adiposity then move HOMA-IR. The identified object is intake, not a direct hormone spell. Hamano, Sawada, Aihara and colleagues ran a one-week open-label crossover in nine overweight Japanese men at the University of Tokyo Hospital. Meals were matched for energy and macros. On the ultra-processed week the men gained 1.1 kg more and ate 813 more kilocalories a day. They chewed less per calorie. That is a second experimental handle on intake and weight. It does not measure HOMA-IR. Chen, Khandpur, Desjardins and colleagues followed the Nurses' Health Study, Nurses' Health Study II, and the Health Professionals Follow-Up Study. Diet came from food-frequency questionnaires coded with NOVA. The outcome was incident type 2 diabetes. Comparing the highest and lowest quintiles of ultra-processed intake, the hazard ratio was 1.46. The same paper's meta-analysis of prospective cohorts found about 12 percent higher diabetes risk for each 10 percent more ultra-processed food by weight. Some subgroups went the other way, including whole-grain breads and yogurt desserts. Those papers do not measure HOMA-IR and they do not identify insulin resistance.

Caveats

Hall is twenty adults, two inpatient weeks. Hamano is nine men, one week per arm, open-label, and they excluded diabetes. Neither trial measured HOMA-IR. Do not export this to "ultra-processed food causes unemployment." Income still sits on who can avoid these foods. Chen is a food-frequency cohort picture of later diabetes. Residual confounding remains. Type 2 diabetes is not HOMA-IR. Some ultra-processed subgroups were associated with lower diabetes risk.

Effect

qualitative. Hall 2019 (N=20) and Hamano 2024 (N=9): ad-lib UPF raised intake and weight vs matched menus. Chen 2023: observational UPF-T2D, not HOMA-IR.

Nodes

Lifestyle & environmentUltra-processed food intakeBiology & endocrinologyInsulin resistance (HOMA-IR)

Named confounders

Cite this page

What Causes What. “Ultra-processed food intake → Insulin resistance (HOMA-IR).” https://whatcauseswhat.org/edges/e-upf-insulin (atlas updated 2026-09-02).

https://whatcauseswhat.org/edges/e-upf-insulin

Papers