Ultra-Processed and Overblown? The Insulin Resistance Debate
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Consumption of processed food causes insulin resistance.
Mostly True
Transcript
ALEX
Hey everybody, welcome back to Truth or Total BS? I'm Alex, this is Episode 9, April 7th, 2026. Today we're asking: does eating processed food actually cause insulin resistance? Like, straight up cause it. Maya's here to tell me yes, and I'm here to say... hold on, not so fast. Maya, you ready?
MAYA
Oh, I'm so ready. The evidence on this one is stacked. Let's go.
ALEX
Okay, but here's my thing. Every major study people cite on this — the NIH reviews, the longitudinal data — they all use words like 'linked to' and 'associated with.' That's correlation language, not causation. There's a huge difference.
MAYA
Fair, but you're cherry-picking the language and ignoring the substance. There's an intervention study published on PubMed Central that compared unprocessed versus ultra-processed diets head to head. The unprocessed diet reduced fasting glucose, insulin, and HOMA-IR — and those results were not observed after ultra-processed food consumption. That's not just correlation, Alex. That's causal evidence.
ALEX
That's one study though. And look, the Diabetes & Metabolism Journal review explicitly says there's ongoing debate about whether the harms come from the processing itself or from the overall poor diet quality that tags along with it. Confounders are everywhere here — obesity, sedentary lifestyle...
MAYA
But that argument actually helps me more than it helps you. Nobody's saying confounders don't exist. What I'm saying is there are convergent mechanistic pathways that explain why UPFs specifically drive insulin resistance. Emulsifiers and artificial sweeteners alter gut microbiome composition and increase gut permeability, which triggers inflammation. That's documented in a mechanistic review looking at how industrial additives cause metabolic dysfunction.
ALEX
Mechanistic plausibility is not the same as proven causation in real humans living real lives. That's a leap.
MAYA
Okay, but stack it up. You've got the intervention data, you've got the mechanisms, and then Duke University research found that fructose — which is everywhere in processed foods — literally causes the liver to keep producing glucose even when insulin is telling it to stop. That's a specific causal pathway for hepatic insulin resistance.
ALEX
Wait, but that's fructose specifically, not 'processing.' Unprocessed foods can be problematic too — the same Diabetes & Metabolism Journal piece notes that red meat, butter, and added sugar increase chronic disease risk regardless of processing.
MAYA
That's a fair nuance, actually. But here's what you're leaving out — a four-year study of young adults found that a 10% increase in UPF intake was linked to a 64% higher risk of prediabetes and a 56% higher likelihood of impaired glucose regulation. That's not a small signal, Alex.
ALEX
But those participants were already overweight! The causal arrow could run the other way — pre-existing metabolic vulnerability driving both the UPF consumption and the insulin resistance.
MAYA
Hmm, that's possible for any single study, sure. But when you have epidemiological data, mechanistic reviews, intervention comparisons, clinical guidance from Cleveland Clinic explicitly linking highly processed diets to insulin resistance, and the fructose pathway from Duke — at some point, convergence matters. You can't wave all of it away with 'but confounders.'
ALEX
I mean... I'm not waving it away. I'm saying the word 'causes' is doing a lot of heavy lifting that the science hasn't fully earned yet.
MAYA
And honestly? I'll meet you partway there. The relationship is real, it's strong, it's biologically plausible, and it's supported from multiple angles. Is the word 'causes' slightly ahead of where the literature is? Maybe a touch. But the direction of effect is solid.
ALEX
Ha! She meets me partway and still wins. Alright folks, we're calling this one Mostly True. The link between ultra-processed food and insulin resistance is real and well-supported, but the hard causal language outruns what the science has nailed down completely. Thanks for listening — catch you next week on Truth or Total BS!