Insulin resistance doesn’t hurt. It doesn’t show up on a scale or in a mirror right away, and for years it can hide behind normal-looking blood sugar. But it may be one of the most important things working against people trying to keep weight off, and most people who have it don’t know.
What it actually is
Insulin’s job is to move glucose out of your blood and into your cells. Think of it as a key that unlocks the door.
With insulin resistance, the locks get stiff. Your muscle, liver, and fat cells stop responding to insulin as easily, so it takes more insulin to get the same job done. Your pancreas compensates by producing extra.
That’s why it can hide for so long. Your blood sugar may look perfectly normal, but only because your body is working much harder, with much higher insulin levels, to keep it there.
How it develops
There usually isn’t one cause. Common contributors include:
- Excess body fat, especially around the organs. Fat stored deep in the belly is particularly linked to insulin resistance.
- Inactivity. Working muscles are one of your biggest glucose sponges. Less movement means less demand for that glucose.
- A diet heavy in refined carbs and sugar. Frequent large blood sugar spikes keep insulin elevated day after day. (See The Insulin Surge.)
- Poor sleep and chronic stress. Both raise stress hormones that push blood sugar up.
- Genetics and age. Family history matters, and risk rises as we get older.
Why it matters for keeping weight off
When insulin runs high most of the time, your body spends more of the day in storage mode. That can make stored fat harder to access, keep hunger and cravings louder, and make maintenance feel like a constant uphill push, even when you’re doing everything “right.”
It also matters well beyond weight. Insulin resistance is closely tied to prediabetes, type 2 diabetes, fatty liver disease, and heart disease. The CDC estimates that more than 1 in 3 American adults has prediabetes, and the large majority of them don’t know it.
Signs worth paying attention to
None of these confirm insulin resistance on their own, but they’re worth raising with your doctor:
- A waistline that keeps growing, even if your weight is fairly stable
- Energy crashes and strong cravings a couple of hours after meals
- Darker, velvety patches of skin, often on the back of the neck or in the armpits
- Multiple skin tags
- High triglycerides, low HDL (“good”) cholesterol, or rising blood pressure on routine bloodwork
How to find out where you stand
This is a conversation to have with your doctor, who can order and interpret the right tests. Ones commonly used include:
- Fasting glucose and HbA1c, which reflect your blood sugar now and over the past few months
- Fasting insulin, which can reveal the problem earlier, while blood sugar still looks normal
- HOMA-IR, a calculation from your fasting glucose and insulin that estimates insulin resistance
- Triglycerides and HDL, since a high ratio between them is often a red flag
The good news: it responds to change
Insulin resistance is one of the most responsive conditions there is. In the landmark Diabetes Prevention Program study, people at high risk who lost a modest 5 to 7 percent of their body weight and got about 150 minutes of activity a week cut their risk of developing type 2 diabetes by 58 percent.
The habits that help are the same ones this site is built on:
- Build and use your muscle. Strength training and regular walking help your muscles take up glucose, even when insulin isn’t working at full strength.
- Flatten the blood sugar curve. Protein first, net carbs moderate, and fast carbs never alone.
- Protect your sleep. Even a few nights of poor sleep can measurably worsen insulin sensitivity.
- Keep weight off once you’ve lost it. That’s the whole point of Weigh to Stay.
If you already take medication for diabetes or blood sugar, make changes to your eating together with your doctor. Lowering carbohydrates can change how much medication you need.
The bottom line
Insulin resistance is quiet, common, and often missed, but it’s also very responsive to the right habits. If maintenance feels harder than it should, it’s worth asking your doctor to look under the hood.