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.

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

When the part of the liver that usually responds to insulin is blocked, the liver makes less fat even when the mouse eats a high-fat diet—but its blood sugar and insulin go up instead.

Blocking insulin signals in the other part of the liver (pericentral zone) cuts down fat buildup in that area without raising blood sugar, even when the mouse eats a high-fat diet.

The front part of the liver needs insulin to make fat when the mouse eats a lot of fat—without it, fat production drops.

Even if you block insulin in the front part of the liver, the mouse still gets high blood sugar when eating a high-fat diet.