Pure curiosity, and the title is pretty much my question. I’ve noticed that nutritional labels (USA) say something like 0g of trans fat, 10g of saturated fat (50% daily value)… but then it lists the total fat as 20g and only 26% of the daily value. 50% obviously doesn’t equal 26% and 10g doesn’t equal 20g so it must mean there are way more types of fat out there than trans and saturated?
If there are other fats, why do labels not provide a breakdown of the others? Why are saturated fats special enough to be listed?
Thanks!
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Total fat, as the name implies, doesn’t differentiate between the different kinds. So if all you eat are saturated fats, you’ll be technically OK on the total, but way over the RDA of saturated fat.
It’s kind of like having a 2000 daily calorie allowance, it wouldn’t be OK if it all came from eating a bowl of sugar.
And yes, there are other fats, *un*saturated being the most obvious example. Those don’t get spelled out separately because unlike trans and saturated they’re the “good” fats. Typically, those would be liquid fats, like olive oil and so on, whereas saturated fats are solid at room temperature. (butter, lard, etc.)
(And trans fats are for the most part unsaturated fats that were artificially processed to make them solid, like butter substitutes. Some are naturally occurring, but the amount is negligible compared to the cheap artificial shortenings in processed food.)
(Air quotes around “good” because any fat is very calorie dense, it’s actually the most calories-per-gram of any food you can eat, so large amounts of it aren’t going to be amazing for you in terms of overall caloric intake.)
But there’s also other minor sources of lipids and cholesterol, etc. (Anything you eat that’s made of cells will include some of those, since they’re components of the cell membrane.)
Also, the reality is a little more complicated than the simple ELI5 explanation, most (probably all, actually?) naturally-occurring fats are a mixture of several different kinds of fatty acids and the proportions determine the consistency, melting point, flavor, etc.
There are also unsaturated fats, and you shouldn’t have the same amount of each amount of fat, which is why total fat is at 26% when saturated fats are at 50%, because you shouldn’t have too much saturated or trans fats.
Unsaturated fats have a double bond in them, making them energy dense, but they also have tails on them that point in the same direction. They can also be called cis fats (as opposed to trans fats), because they point the same direction. Picture it like a “u” shape. This u shape means they don’t stick together easily, leaving them liquid at room temperature and generally less dense. (Olive oil)
Saturated fats don’t have that double bond, but they also don’t have the u shape. Their tails point in opposite directions, like a “z” shape. This shape let’s them stick together (like layers), so they can be solid at room temperature. Since they are more dense, this is what makes them saturated. (Butter)
Trans fats have both the z shape and a double bond, so they have the extra energy and stick together, meaning a lot of energy get packed into a smaller profile. (Fryer grease)
You need fat in your diet, but that should consist of mostly unsaturated fat, but you do need saturated fats too. You don’t need trans fats at all, but when you do indulge, you should only have a little.
Trans fats are one type of unsaturated fat, but it’s rare naturally and mostly occurs in processed foods because hydrogenated vegetable oil stores well without refrigeration. In addition to trans and saturated fats are many other monounsaturated and polyunsaturated fats that are cis rather than trans.
They’re all just descriptions of the types of fatty acids present and the kinds of bonds and orientations in the long carbon chains that define fats.
Because you should eat very little saturated fats, and no trans fats, so the RDA is lower, they are unhealthy. Your diet should contain healthy fats, and the RDA for that is higher.
yeah man there are definitely other fats like monounsaturated and polyunsaturated fats which are usually lumped into that total fat number but not always listed separately. its kinda weird but probably cause they wanna keep it simple. saturated fats have a bad rep so they get the spotlight on food labels. it’s all about keeping it healthy while making it easier for people to understand
yo man great question. so yeah there are other types of fat like monounsaturated and polyunsaturated fats. they just don’t always get their own spot on labels. saturated fats are special cause they affect heart health and stuff. labeling rules can be a lil weird but hey at least they help us keep track of what we eat right
So fats, chemically, are long chains of carbon and hydrogen. Aside from the ends, each carbon is bonded to two other carbons and two hydrogens.
Saturated fats have two hydrogens attached to every carbon (which, aside from the two ends, is the most hydrogens that the carbon in the chain can have). They make long, straight chains that stack very nicely together and are solid at biological temperatures.
Unsaturated fats are missing some number of hydrogens (always in multiples of two) and those carbons instead have a double bond. “Trans” refers to the position of the remaining hydrogen on the doubly bonded carbons. If both remaining hydrogens are on the same side, it is “cis”, if they are on opposite sides, they are trans. Unsaturated fats will sometimes be labelled as “mono” (having one double bond) or “poly” (having many double bonds).
Because trans fats are only one subcategory of unsaturated fats, your sum will always be less than total fat. You’d need cis and trans unsaturated plus saturated to get to total fat.
Saturated fats and trans fats are specifically mentioned because they’re involved in clogging up your arteries, causing high blood pressure and all sorts of things you don’t want.
The other kind of fats, unsaturated fats (typically divided into monounsaturated fats and polyunsaturated fats) are not really bad for you (in moderation). In fact, your body needs fatty acids to survive and of your total caloric intake about 20-30% should come from fat (which isn’t a whole lot since fat is incredibly calorie dense. 9 calories per gram as opposed to 4 per gram for carbohydrates and protein).
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