Posted by Werner Mansfeld
on June 24, 2026
Insulin resistance has a reputation as a malfunction — something gone wrong in the body. Looking at how other animals use the exact same biological tool tells a different story: insulin resistance is a feature, not a bug. The problem isn’t that humans have access to it. The problem is that, for most of us, it never turns off.
The Penguin That Fasts for Four Months
Before a male emperor penguin marches inland to incubate an egg through the Antarctic winter, it doubles its body fat by gorging on squid and fish. It will then go without food for as long as four months. To survive that fast, its body shifts into a state that closely resembles human insulin resistance — prioritizing fat storage and conserving glucose for only its most essential functions.
This isn’t a disease state for the penguin. It’s a precisely timed adaptation that allows survival through a predictable period of scarcity. Once that period ends, the penguin’s metabolism shifts back.
The Hummingbird That “Develops Diabetes” Every Day
Hummingbirds offer an even more striking example. With extraordinarily high metabolic rates, they consume up to four times their body weight in nectar daily. By the end of the day, many hummingbirds have blood sugar levels exceeding 700 — far beyond what would be considered a medical emergency in a human — along with a fatty liver and a temporary state of metabolic syndrome.
By the following morning, they’re back to normal. No complications, no lasting damage. The hummingbird’s body cycles in and out of a severe insulin-resistant state every single day, as part of its normal physiology.
What Separates Them From Us
The key difference isn’t the presence of the mechanism — it’s the duration. Penguins and hummingbirds activate intense versions of fat-storage and insulin-resistant states for defined, temporary periods, then return to baseline. The biological tool gets used as intended: turned on when needed, turned off when it isn’t.
In modern humans, a constant, year-round supply of the dietary triggers that activate this same response means the “off” signal rarely arrives. Insulin resistance that should be a short-term, situational adaptation instead becomes a permanent, chronic state — and that’s where the damage associated with type 2 diabetes, cardiovascular disease, and the broader diabesity picture actually originates. It’s not the mechanism that’s harmful. It’s the mechanism getting stuck.
It’s not the mechanism that’s harmful. It’s the mechanism getting stuck.
Why This Matters for How You Think About Your Own Metabolism
This isn’t a suggestion that human insulin resistance is harmless because animals use a similar process — the chronic, sustained version humans experience is genuinely damaging over time, in a way the penguin’s seasonal fast or the hummingbird’s daily cycle is not. But it is a useful reminder that the underlying machinery isn’t broken or foreign. It’s a normal biological tool that’s being triggered far more often, and for far longer, than it was ever designed to run.
The practical implication
If insulin resistance is fundamentally about a switch staying on too long rather than a switch being broken, the path forward is about removing the signals keeping it activated — not fighting against some permanently damaged piece of biology. That’s a meaningfully more hopeful starting point, and it’s consistent with what the research on reversibility and remission actually shows.
