Chronic consumption of a diet containing 34% fructose, in the absence of weight gain, is associated with increased hepatic triglyceride accumulation, insulin resistance, elevated plasma cholesterol and triglycerides, and signs of necroinflammation in male C57BL/6 mice.

When fructose is consumed in large amounts, the liver breaks it down in a way that floods the cell with building blocks for fat. This causes the liver to make more fat and stop burning existing fat, so fat builds up inside liver cells. At the same time, the liver becomes resistant to insulin, so it keeps producing glucose even when blood sugar is already high. The excess fat and sugar stress the liver cells, damaging them and triggering inflammation that kills cells and recruits immune cells, leading to liver damage.