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June 12, 2026 · 8 min read

Fat of The Land - Part 4 - The Fat We Made

By Raiden DeLuca

Three of the four kinds of fat come from nature, and the last post made the case that none of them is the enemy you were told it was. The fourth is the odd one out. We made it ourselves, in a factory, and it is the one fat I would actually tell you to avoid. Its story is the strangest stretch of this whole subject, because it is not really about chemistry at all, it is about being handed the wrong answer with a lot of confidence, which is something I see happen again and again in the food industry, even now.

A bend, and a bend forced straight

Back in the last post, the picture was a train. A saturated fat is a train on straight track, every car in line, so it packs together tightly and sets into a solid, the way butter does. An unsaturated fat has a bend in it, a kink in the track, and that kink stops the cars from packing in close, which is why those fats stay liquid, the way oil does.

There is one more thing about that bend, and it turns out to be the whole story of trans fat: the bend can sit two different ways.

Coming out of the kink, the rest of the chain can either curve back toward the same side, which keeps the train bent, or cross over to the opposite side, which lets it straighten out and run on in a line. The curved version is the one nature uses, essentially always, and that curve matters, because it is what keeps the oil liquid and your cell membranes flexible. Chemists call it cis, Latin for “this side.” The straightened version is called trans, Latin for “across,” and it barely shows up in nature at all.

That straightening is the whole problem. A trans fat still has its bend point, so on paper it is still an unsaturated fat. But with the chain running straight instead of curving, the train packs in tightly again, exactly the way a saturated fat does. You end up with an unsaturated fat wearing a saturated fat’s straight shape, the same handful of atoms forced into a line, like a kink hammered out of a wire. And nature almost never makes that straightened shape on its own.

Why we made it

If trans fat barely exists in nature, where did all of it come from? We manufactured it, on purpose, through a process called hydrogenation.

The motive was practical, even reasonable enough at first. Liquid vegetable oil is cheap, but it is liquid, and being polyunsaturated it is fragile and turns rancid, the exact weakness we covered last time. Food makers wanted something with the price of oil and the body of butter: solid, spreadable, and stable on a shelf for months. So they ran hydrogen through the oil under heat and pressure, filling in some of the double bonds and straightening the kinks. Take it all the way and you get a hard, fully saturated fat. Stop partway, which is cheaper and gives a better texture, and you get partial hydrogenation, and partial hydrogenation is the step that twists a share of those remaining bends into the straight, trans shape. Margarine, vegetable shortening, and the fat in a great deal of packaged baked goods and fried food were all this same thing: liquid oil with its kinks hammered flat.

The one fat the science agrees on

I have tried across this series to be honest about how unsettled this field is. Saturated fat, cholesterol, seed oils, the evidence on each has two reasonable sides. Trans fat is the exception, the one place the science is not close.

Most fats nudge your cholesterol in a single direction. Trans fat pushes it the wrong way at both ends at once, raising LDL, the cholesterol tied to heart disease, while lowering HDL, the kind generally considered protective. On top of that it appears to drive inflammation and damage the lining of the arteries. The harm per calorie runs markedly worse than saturated fat, and the large Harvard cohort studies found that even a small share of daily calories from trans fat tracked with a meaningfully higher rate of heart disease. One major review put it about as plainly as the field ever does: real potential for harm, and no benefit to set against it. There is no amount your body needs, and no amount that has been shown to be safe.

The part that should bother you

Now lay that beside what was being said at the dinner table.

Margarine began as a cheap stand-in for butter and spread widely when butter was rationed during the Second World War. Then, through the second half of the century, as saturated fat was named the great enemy of the heart and people were urged to put the butter down, the hydrogenated spreads were sold to them as the heart-healthy choice. The modern, responsible, doctor-approved move was to switch from butter to margarine.

So millions of people, doing exactly what they were told was good for their hearts, were steered off a stable, natural fat and onto the single most harmful one ever to reach a plate. The advice was not just incomplete, it was backwards, and it stood that way for decades before anyone reversed it. If you have ever wondered why I am wary of sweeping, confident dietary commandments, this is a good part of the reason. The official answer did not merely fall short of the truth, it pointed people directly at the one fat they most needed to avoid.

One honest distinction

A trace of natural trans fat does exist. It is made in the stomachs of cows and other ruminant animals, so small amounts show up in butter, beef, and dairy. Those natural trans fats, in the modest amounts real food contains, have not shown the same harm as the industrial kind in the research we have, and some studies suggest a few may even be neutral. The villain in this story is not the word trans on a diagram. It is specifically the manufactured, partially hydrogenated fat we invented and poured into the food supply.

Corruption, not creation

There is a bigger pattern under all of this, and trans fat is the clearest example of it I know.

Nothing in that factory created a good thing. Hydrogenation did not invent a new fat or add a new nutrient to the world. It took a fat that already existed, one pressed from a plant, fragile and living in the way real food is, and it bent the molecule into a shape that does not occur in creation, a shape the body cannot use and is actively harmed by. The raw material was good, the deforming was ours, done for the sake of shelf life and cost. That is the pattern underneath so much of what ails the modern diet. Not the invention of new evils, but the quiet corruption of things that were made good by God.

The practical side of this, the part where you avoid trans fat, is pretty easy now, mostly because the law did the work for us. In 2015 the FDA ruled that partially hydrogenated oils were no longer safe to add to food and gave the industry roughly three years, until 2018, to take them out, with a little more time for products already moving through stores. So the worst of it is already gone from American shelves. You can finish the job yourself by reading a label and leaving behind anything that still lists partially hydrogenated oil, mostly a few imported or long-life processed products. But the ingredient was never really the lesson, the lesson here is the pattern. When you find a natural thing that has been altered to be cheaper, harder, or longer-lasting than God ever made it, slow down and ask what got traded away to get there. With trans fat, we found out the hard way, and it took us half a century to admit it.

That is the thread under this whole blog, and the real reason I care about any of it. We were given good food by a good Creator, and most of what harms us now is not some brand-new evil made out of nothing, but a good thing bent out of the shape He gave it, for the sake of money and shelf life and convenience. The pull is always to trust the cleverness of the created over the wisdom of the One who made it, and trans fat is just one place we did exactly that and paid for it. So I would rather eat, as best I can, the way He made things in the first place.

From here the series keeps pulling on the fat thread. Next I want to get into the balance between omega-3 and omega-6, the ratio you have probably heard people argue about, why the modern version of it leans so hard one way, and how much of the worry around it holds up. That is where we go next.

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