Insulin resistance

Insulin resistance means muscle, liver and fat cells no longer respond normally to insulin. The pancreas compensates by secreting more, so blood glucose can stay normal for years while insulin levels climb — which is why fasting insulin often flags the problem long before fasting glucose does.

It matters because it sits upstream of a great deal: type 2 diabetes, metabolic syndrome, fatty liver, polycystic ovary syndrome and elevated cardiovascular risk. It is driven by excess visceral fat, physical inactivity, poor sleep and sustained energy surplus.

In practice it is substantially reversible. Losing visceral fat, resistance training, regular aerobic activity and simply walking after meals all improve it measurably — often faster and more reliably than any dietary composition change alone.