A study by Harvard Medical School, albeit conducted on mice, revealed that a diet rich in fructose and fat damages the liver, compromising its ability to manage fat and thus promoting non-alcoholic steatosis.
According to what the researchers explained, in fact, the combination of sugars and fats is bad for the liver if these sugars are not glucose but fructose.

I will try to explain this in practical terms.

Fructose is a sugar contained mainly in fruit, honey but also in many industrial products.
Especially in these products, from snacks to ice cream to savory products and drinks, fructose is present as glucose-fructose syrup or corn syrup. If a person has a diet that is also high in fat, for example the fats added in these products, condiments, fries, sauces, the liver becomes intoxicated.
The same thing does NOT happen if one is on a diet that is high in fructose but low in fat. For example, anyone who eats only fruit or honey but minimizes fat will never have this problem.
If one is on a diet high in fat but low in sugar of any kind.
And not even if one has a diet rich in glucose and fat.

Now, dieting with foods that only contain glucose is difficult.
Unless you only eat foods sugary with dextrose / glucose . Fruit also contains fructose, in varying percentages, and the same goes for sugar, or sucrose . So anything that is sweetened contains fructose, as a rule.

DIET RICH IN FRUCTOSE AND FATS: THE LIVER-HARMFUL COMBINATION

For the same calories, the researchers, who published the study in the journal Cell Metabolism , explain that a high-fructose diet that also has high fat prompts the liver to produce and store fat. So on the one hand the liver synthesizes new fats, on the other hand it accumulates the fats that come from the same diet.
The result is that the liver becomes enlarged and no longer functions well. Hence, the metabolic syndrome.
The typical Western diet is rich in both fructose, due to industrial foods (certainly not due to an excess of fruit!), And fat.
This combination of fat and fructose would explain the tendency for researchers to gain more weight than excess calories.

DIET RICH IN FRUCTOSE AND FATS: HOW TO AVOID IT

Avoiding a diet rich in fructose and fat is simple.
All products with corn syrup or glucose-fructose syrup should be excluded from the diet and sugar should be reduced if we are unable to follow a low-fat diet. So if we love sweets, the advice is to reduce fat as much as possible. Both by checking the labels and by paying attention to fatty foods of any kind. For example: cookies are not only sweet, they also have a good fat content.
If, on the other hand, our diet is rich in fatty foods, it is better to reduce sugars.