I don’t know anything about so-called “trans fats” so I’m afraid I don’t have a real view on whether or not they should be banned. It does occur to me, however, to say something about the general structure of these arguments. Namely, that in the realm of food-consumption, there are oftentimes tradeoffs between deliciousness and health. But it’s not a symmetrical relationship. We can quantify the unhealthiness of, say, Swedish fish much more precisely than we can quantify the tastiness of said candies.
One result of this is oftentimes to unduly bias policy in favor of health and away from fun. You can see this especially in the discussion of, say, marijuana. Personally, I don’t care for the stuff. Obviously, though, many people do enjoy it. Under the circumstances, reducing marijuana consumption is both a cost and a benefit of marijuana prohibition — making people healthier, but also leading people to have less fun. But while scientists can tell us something about the ill health consequences of pot smoking, it’s hard to say exactly what the “fun cost” of making it harder for people to get high is. Which is where liberty tends to enter the picture — people are left to muddle-through on their own terms trying to decide how much fun is worth how much ill-health and, as you can see from the large amount of food-and-exercise-related guilt we see among high-SES Americans, often not muddling-through in a way they find completely satisfactory.