For a long time, a diagnosis of “fatty liver” was a fairly unambiguous sign that the patient (usually “he”) had had too much alcohol.

We already identified alcohol, from certain angles, as a “preferred fuel” back in the chapter The Preferred Fuel(1).

The Dietary Change

Everyone has surely heard it by now: sugar consumption keeps rising, and has done for a long time - enormously so, especially compared with the long evolutionary span over which humans developed.

Not least because the dietary guidelines told us that fat is largely to be avoided - and foods stripped of their fat simply don’t taste as good any more. So you have to add other flavour carriers - and since, for example, fruit in low-fat yoghurt was popular, these were simply sweetened more heavily.

It for industrial production it also helps that sugar is quite cheap.

The Phenomenon

For some time now, though, fatty liver has been diagnosed not only in overweight 50-plus-year-old alcoholics but also in adolescents and children, in whom it must have come about without any alcohol consumption. In this context, until recently people spoke of a “non-alcoholic fatty liver” (NAFL). But since negative definitions aren’t popular in the long run, it’s now called, more correctly but less catchily, MASLD - or, spelled out and thoroughly unwieldy, Metabolic dysfunction-Associated Steatotic Liver Disease(2). That name points unambiguously to the connection that was found: the metabolism.

The Association

With that we’re basically done - this much seems well established(3). But to do the series justice and fold in a bit of speculation, I’ll naturally go a little further. First, though, an explanation of the phenomenon:

For the liver to become fatty, it has to generate new fat in excess - this is called de novo lipogenesis is the process by which the body creates new fat from carbohydrates, with the purpose of storage for later use → more. This excess is reached when the liver has to detoxify and store very large amounts of substances - so much that proper storage in the places actually intended for it doesn’t happen.

What substances are those?

One we’ve already identified as “Schrödinger’s foodstuff”, using foie gras as the example: grain - an indispensable staple food, but whose diametrically opposed highlighted properties differ depending on which creature eats it. And the term non-alcoholic fatty liver has already cropped up in a similar context too:

This article is about another one - about a not-uncommon ingredient of our daily diet, and its properties, which we’ve likewise already met in a different context.

Related articles

Two combine harvesters in a large wheat field.
Grains

Grains are among the most fundamental staples - most people can hardly imagine doing without them. Yet depending on whether they are eaten by humans or fed to animals, they are credited with diametrically opposite properties. Schrödinger’s food

Sign 'Due to health risks don't feed the ducks or geese'
Don't feed the animals

Why aren’t you supposed to feed the ducks in the park or the animals at the zoo - and what we can learn from it

Flour or icing sugar (you cannot quite tell which) being sifted into a bowl.
Sugar - What Exactly Is It?

A long answer to a trivial question - sugar is a great deal more than the stuff sold under that name in the supermarket. And it’s not necessarily sweet

Fructose

Well hidden in the article about sugar was an important property of fructose: the human body can break it down almost exclusively(4) in the liver, and the metabolic pathway by which that happens is nearly identical to that of alcohol(5) - and that’s the spoiler for this article already.

Absurd Guidelines

Here we finally get to the free association, and take a look at where this - taken further - would lead us today:

According to the Deutsche Gesellschaft für Ernährung - German Nutritional Society, a largely government funded NGO, designated as appointed authority on nutritional matters (and the WHO), consuming 350 g of sugar per week is acceptable. From the sugar article we know that this corresponds to 175 g of fructose. On that premise, it would now of course be interesting to be able to convert between fructose and alcohol.

I haven’t found a concrete reference for an equivalent conversion factor - by molecular weight, fructose and ethanol (converted to the same number of carbon atoms) are relatively comparable, which would give a factor of 1.3:1, but apparently ethanol is in fact a little more harmful than fructose: Some estimations have given me a value closer to 2:1(7), which I have crosschecked with two independent AI engines. - and since this is a qualitative statement, a watertight quantitative value is likely to be hard to come by (I’m happy to take real references, though: the comments are open)

Accordingly, the amount of alcohol equivalent to the fructose would be a weekly consumption of 87.5 g of alcohol (if you forgo sugar). And anyone who goes easy on fruit(8), which also contains fructose, could even round up a bit. That would be a large beer every 1-2 days - and if you don’t like beer, you just drink the same amount of cola or orange juice instead. In fact, you can even treat yourself half a glass more.

A buzz, possibly without the blood-alcohol reading. The liver, at least, notices no difference.

Won’t Somebody Think of the Children?

Quick vibe check: who would grant their children a large beer every 1-2 days?

And an equally large orange juice?

A New Guideline, in Plain Language

Let’s compare once more with the other guidelines and conclude:

Drink more beer or cola than you eat meat(1)!

DGE (indirectly, following this derivation)

Because, as we know:

Nobody's Taking Away Your Pizza

A pizza and a cola on a table
The DGE would of course never green-light alcohol - but with the 350 g of sugar per week, they have no problem with cola and orange juice.
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  1. If you don’t read the sarcasm here, please read the linked article.
  2. In German, equally unwieldy: Metabolische Dysfunktion-assoziierte steatotische Lebererkrankung
  3. The cleanest human evidence comes from a controlled study: fructose-sweetened - not glucose-sweetened - drinks increased de novo lipogenesis, visceral fat and blood lipids, and lowered insulin sensitivity. Kimber L. Stanhope et al., “Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans”, J Clin Invest 2009;119(5):1322-1334 (open access).
  4. Small amounts can in fact also be converted in the small intestine. But as we see over the course of the article, I focus above all on very rapidly available sugars, which overwhelm this mechanism - so I disregard it.
  5. Robert H. Lustig “Fructose: It’s ‘Alcohol Without the Buzz’” Very instructive in this paper: Table 1, which shows that a can of soft drink and a can of beer set the liver comparable tasks (measured in calories).
  6. Strictly speaking, the liver does have a choice: there is also a pathway to glucose - which, however, can only be taken if the body’s glucose and glycogen stores can still take more. But together with the fructose, the body gets the same amount of glucose from table sugar, and the dietary guidelines otherwise encourage high carbohydrate intake too, so one can assume this pathway is almost permanently barred. Ergo: no choice but de novo lipogenesis.
  7. Back-of-envelope calculation for the conversion factor: in terms of carbon atoms, 1 fructose molecule is comparable to 3 ethanol molecules (C6H12O6 vs C2H6O; by molecular weight 180 g/mol vs 46 g/mol; 46*3=138, 180:138 = 1.3:1). However, ethanol actively suppresses the oxidation of existing fat, so it has a stronger effect than fructose. And since ethanol’s route is genuinely inescapable and predetermined, whereas for fructose there is - at least in theory - still the escape via glucose(6), a tie-breaker is needed: fructose is less reactive than ethanol - evident from the calorific value of 7 kcal/g for ethanol versus 4 kcal/g for fructose. I round to 2:1.
  8. All right - the fruit is a stretch (see also (4)) - at least those aren’t empty calories, but otherwise the nutritional value of fructose and alcohol is (apart from the energy content) completely identical: zero.