Why would you buy a processed food that tastes worse than what it was designed to replace, doesn’t exist in nature, and helps kill you?

Either because you had no choice or had been misled about its essence. And that’s exactly the situation most Americans find themselves in regarding partially hydrogenated oils and the trans fats they contain.

The good news is that — finally — the Food and Drug Administration isbanning food containing trans fats, although really only sort of, and really only after overwhelming evidence (and more than one lawsuit) made their dangers impossible to ignore. And in typical pro-industry fashion, the F.D.A. is not only allowing companies three years to get trans fats out of most foods, but will consider manufacturers’ petitions to keep them in.

Partially hydrogenated oils were invented 100 years ago, and quickly became popular in the form of margarine and vegetable shortening, like Crisco; their inclusion in thousands of other products and use as frying oil or coffee “whitener” is more recent. Thanks to their extension of shelf life, cost benefits to the processed food industry and the unfounded notion that they were healthier than the fats they replaced (asserted even by well-intentioned health organizations), they became ubiquitous. And they remain in many processed foods, supplanting real ingredients like butter, lard and less processed oils.

But partially hydrogenated oils have benefited no one except their manufacturers and the producers of the junk that includes them. And the three-year phaseout means more deaths from people consuming a substance that should have been taken off the market at least a decade ago. (Studies finding that trans fats were worse than animal fats were publishedin the early 1990s.)

The F.D.A. knows this: Its acting commissioner, Stephen Ostroff, said that eliminating trans fats “is expected to reduce coronary heart disease and prevent thousands of fatal heart attacks every year.”

Why wait three years? Why not get these heart-stopping products off the shelves now, as we do when food is contaminated with E. coli? If the evidence is that trans fats are more harmful than other fats, and other fats exist, why delay? Protecting Big Food’s profits is the only possible answer.

It may be really expensive for Big Food to replace partially hydrogenated oils — the F.D.A. itself estimates the cost at $6 billion — mainly because trying to mimic their performance is going to be tricky. Tough luck. No one can possibly estimate the profits that these oils have garnered or their damage to the public. The agency’s analysis also estimates that health care and other costs will decline by $140 billion in the next 20 years as a result of declining trans fat consumption.

Once again it’s clear that too often the primary concern of government watchdog agencies is to protect corporate profits rather than public health. Otherwise we’d know how much sugar was in processed food, we’d have long since banned the routine use of antibiotics in animal production, we’d have salmonella-free chicken and we’d have forbidden the marketing and sale of soda and other liquid candy to minors.

Instead, people sicken and die from eating “food” that’s known to be unhealthy. We let industry buy time — at our expense — while they research and develop alternatives that might be no better than the stuff they’ll replace, and whose safety still won’t be guaranteed by the F.D.A.

Lard is not the “healthiest” food in the world but at least no one tells you it’s “better” than other naturally occurring fats, as was claimed about trans fats. No one with a palate ever said that partially hydrogenated oils tasted better than naturally occurring fats.

And as everyone should know by now, a well-made pie, a beautifully frosted cake and perfectly crisped fried food are treats, occasional indulgences. Let’s make them as well as we can, rather than take short cuts using phony ingredients that don’t taste good and are unhealthy. That should be a one-two punch that clears the market of many “alternative” fats — and, for that matter, of many other ultraprocessed “foods” that benefit industry and harm consumers