People with very overweight and severe fatty liver also have much worse insulin resistance — meaning their bodies don’t respond well to insulin — compared to those with milder liver fat.

In middle-aged people who are overweight, eating fewer carbs and more fat for 15 weeks might help their body respond better to insulin, while cutting calories on a low-fat diet could actually make insulin work worse — and these changes happen even if both groups lose about the same amount of weight.

In people with obesity and prediabetes, losing weight through diet improves how the liver responds to insulin, but does not improve how muscles and other tissues respond to insulin.

In very overweight people with severe fatty liver, the less SIRT1 gene activity they have in their belly fat, the worse their body’s response to insulin tends to be — meaning their blood sugar control is poorer.

Eating too many carbs and calories — especially from sugary or processed foods — is what mainly causes fatty liver, not eating fat. Cutting out carbs or going on a carnivore diet might help reverse it.

Eating a low-carb diet for 12 weeks helps people with type 2 diabetes and obesity improve how their liver responds to insulin, making it work better without needing to change their medications.