The liver is a stupid organ. It has only limited abilities to express itself. It can necrotise, swell, inflame, clot and scarify. The liver can become leaky, it can sometimes hurt and its plumbing can clog. And then the liver can be fatty. For some time already, we know that, for example, several viruses can cause the inflammation, and that drugs, viruses and autoimmunity cause most of the necrosis, etc. Luckily, for the majority of these causes, we have more or less reliable methods to pin them down. Not so for the fatty sign because, when turning fatty, the liver is at its most stupid. On a communication scale and compared with the eloquent monologue of a viral hepatitis, turning fatty would rate as a grunt. It is never entirely clear what causes a grunt or what is meant by grunting, as it is never clear what provokes fatty infiltration of the liver or what the liver wants to convey by turning fatty. A grunt can be an expression of pain, but also of pleasure. Is it time to expand the liver’s vocabulary, or could there also be something wrong with us, the audience?

When turning fatty, the liver is at its most stupid

When fatty liver is not associated with moderate to severe alcohol intake and the most prevalent liver diseases are excluded, it is called “non-alcoholic fatty liver disease” (NAFLD). When the fatty liver is also inflamed, we call it “non-alcoholic steatohepatitis” (NASH). However, there is a very long and ever-expanding list of causes of fatty livers, which cannot simply be named NAFLD/NASH (table 1). Also on a more theoretical level, there is a problem with NAFLD and NASH: they are “non”-diseases, exclusion diagnoses: it’s not a bird, it’s not a plane, so it must be Superman. Therefore, …