Hepatic steatosis (non-alcoholic fatty liver)
An excessive build-up of fat in the liver not linked to alcohol, often silent, now the most widespread liver disease and strongly tied to metabolic syndrome.
Non-alcoholic fatty liver disease (NAFLD, or MASLD under the new 2023 nomenclature) means a liver infiltrated with fat (>5% of its weight) in a person who drinks little or no alcohol. It has become the most common liver disease in the world (~25 to 30% of adults), alongside the epidemic of obesity and diabetes.
The original angle (fructose, the fuel of fatty liver): a major counter-intuitive point: it is not dietary « fat » that makes the liver fatty, but mainly excess sugar, especially fructose.
The mechanism: fructose is metabolised almost exclusively by the liver. In excess (fizzy drinks, syrups, sweets), the liver converts it into fat (de novo lipogenesis), which builds up on the spot. This is why sugary drinks are a major risk factor, and why cutting sugar (more than fat) is the key.
Silent progression: simple steatosis is often asymptomatic (found by chance). But it can progress to steatohepatitis (NASH/MASH), with inflammation and damage, then fibrosis, cirrhosis and even liver cancer. A silent liver killer.
Reversibility (good news): in the early stages, fatty liver is largely reversible. The levers:
- Cut back on sugar and fructose (fizzy drinks, juices, sweets), the most effective action
- Lose weight (even 7 to 10% of body weight clearly improves things)
- Physical activity (reduces liver fat independently of weight)
- The Mediterranean diet (the most studied and recommended for this condition)
- Coffee (associated with a protective effect on the liver in studies)
There is a strong link with insulin resistance and metabolic syndrome: fatty liver is often its liver manifestation.