Insulin Resistance: The Mechanism, the Signs, and the Tests to Ask For
What is insulin resistance, and how do you know if you have it? The mechanism explained plainly, the signs to watch for, and what actually helps.
"My dr. told me to eat a low GI diet for insulin resistance but I'm not sure where to start."
The mechanism, without the jargon
Insulin's job is to let glucose out of your bloodstream and into your cells. Think of it as knocking on the door.
With insulin resistance, the cells stop answering as readily. Your pancreas compensates by knocking harder — producing more insulin — and for a while that works. Blood sugar stays normal because insulin levels are quietly climbing to keep it there.
That compensation period can last years. It's why insulin resistance usually precedes a prediabetes diagnosis by a long stretch, and why the diagnosis so often feels sudden when it isn't.
Eventually the pancreas can't keep up, and glucose starts rising. That's when the number on the test moves.
The signs
None of these are diagnostic on their own, but together they're a pattern worth noticing:
- A crash 30 to 60 minutes after eating — the single most reported sign among women I work with
- Weight settling around the middle specifically
- Intense afternoon fatigue that food fixes briefly
- Cravings for something sweet or starchy that feel physical rather than psychological
- Skin tags, or darkened velvety patches at the neck or armpits
- Weight that won't move despite genuine effort
How it's actually tested
A standard A1C or fasting glucose test can look normal while insulin resistance is well established, because insulin is doing the work of keeping them normal.
Better markers to ask about: fasting insulin, and the HOMA-IR calculation which combines fasting insulin and glucose. Neither is routinely ordered, so you generally have to request them.
Why it matters more after menopause
Estrogen does two things that matter here. It supports insulin sensitivity, and it influences where fat is stored — toward hips and thighs rather than the abdomen.
As it declines, the storage pattern shifts. Fat moves to the middle, and the fat stored there is visceral: metabolically active tissue sitting around the organs, strongly associated with insulin resistance and metabolic syndrome.
Researchers still debate how much of the insulin resistance comes from the hormonal change itself versus from that redistribution. What is not debated is the redistribution, or what visceral fat does once it is there. Add the muscle loss that accompanies this stage of life — and muscle is the body's largest site of glucose disposal — and you have the full picture.
Nothing about you broke. The conditions changed.
It is also why a way of eating that worked at 40 can stop working at 55 with nothing else having changed.
What helps
The same levers, and the order matters: protein at breakfast, carbohydrate paired and placed at midday, movement after meals, and enough sleep. Muscle is the largest site of glucose disposal in the body, which is why resistance training matters here more than cardio.
Try this week: notice whether you crash 30 to 60 minutes after eating, and what you ate. That pattern is the most useful thing you can bring to your next appointment.
Education, not medical advice. Ask your doctor about fasting insulin if this pattern sounds familiar.