The liver isn’t the same all the way through—different parts react differently when insulin stops working, leading to very different outcomes for fat and sugar.

Where in the liver insulin resistance happens determines whether it causes high blood sugar, high fat, or neither.

Turning off insulin signals in the back part of the liver cuts fat without making the body pump out more insulin.

When mice eat a high-fat diet, fat builds up in both parts of the liver—but blocking insulin in just one part stops fat from building up there.

When the front part of the liver doesn’t respond to insulin, the body makes more insulin to try to compensate.

Insulin signals in the back part of the liver help fat build up there when the mouse eats a high-fat diet.