If healthy men eat about 80 grams of sugar (like table sugar or fruit sugar) every day for 7 weeks, their body still burns fat normally in muscles and blood—but their liver starts making more fat.

If healthy men eat 80 grams of fructose or table sugar every day for 7 weeks, their liver starts making and releasing about twice as much fat as before—but eating the same amount of plain glucose doesn’t do that.

If you swap out regular sugar or glucose for fructose in your diet without changing how many calories you eat, it might slightly reduce a type of fat in your blood called triglycerides — which could be a small good thing for your heart and liver.

If you eat a lot of fructose—like from sugary drinks—for just 9 days, even without gaining weight or eating more calories overall, your liver becomes less responsive to insulin, which means it keeps making sugar when it shouldn’t.

When people eat a lot of fructose (like in sugary drinks), their liver has a harder time burning fat for energy, especially if they're also eating a lot of fat — which can lead to fat building up in the liver.

Eating too much fructose—like the sugar in soda and candy—can slow down your liver’s ability to burn fat, making fat build up and mess up your metabolism.