Lipids (aka fats!)

Lipids (aka fats!)

Fat! Perhaps one of the scariest words in our society for the past fifty years. We don’t want to eat it, because we think we’ll become it. Well, I’ve got good news! Not only are dietary fats not the same thing as body fat, they’re super beneficial and super necessary for our bodies. Let’s bury the myths about fat, and learn about this tasty macronutrient.

Learn about the macronutrient lipids in this "Nutrition in a Nutshell!"

What are lipids, and what do they do for my body?

Lipids, more commonly known as fats, are a macronutrient that provide nine calories per gram. Nine! That’s more than double carbohydrates and proteins, so it’s important to consume fats in moderation, and eat the right kinds.

Triglycerides

We’ll have to get a bit chemical to understand fats (sorry . . . feel free to skip ahead to the last few paragraphs of this section for a very quick recap on roles of fats!). Fatty acids are composed of long chains of carbon with hydrogen atoms filling any available bonds, or at least this is the case in a saturated fat. Imagine three chains stacked in parallel lines, all connected to another perpendicular molecule at one end – a glycerol molecule. If you’re picturing something that looks like an E, you’ve got the idea of what a fat called a triglyceride looks like. A molecule of fat. Not so scary now, is it?

A triglyceride molecule with two saturated fatty acids and one monounsaturated fatty acid. Source: American Chemical Society.

A triglyceride is composed of the three kinds of fatty acids – saturated and unsaturated (mono- and poly-). I already touched on saturated fats. A saturated fat is filled with as much hydrogen as possible, with no double bonds between any two atoms of carbon. Since these molecules stack nicely and tightly together, they are solid at room temperature. These would be things like animal fat or coconut oil. In our diet, the current consensus is to limit these types of fats in order to protect fatty plaque from building in our arteries.

If a fatty acid chain isn’t saturated with hydrogen, there would exist a double bond between two carbons. If only one double bond exists, you have a monounsaturated fat. Two or more, and it’s a polyunsaturated fat. These double bonds cause the molecules to kink, which means they can’t stack nice and close, which means this fat will be liquid. Think of cooking oils! Depending on the location of the double bond, the name and properties of the fat changes a little bit. Many people have heard of omega-3 and omega-6 fatty acids. These are examples of unsaturated fats with the double bond in different locations. (Incidentally, these two are the only ones our body can’t make – they’re essential in our diet!)

trans fat occurs when an unsaturated fat is artificially saturated with hydrogen, a process called hydrogenation which causes the hydrogens to be placed a little weird. They’re considered to be the worst-for-you kind of fat. An example of a trans fat would be margarine.

Eggs are dairy products contain lipids, or fats.

All those together are just triglycerides – just one kind of fat! Triglycerides are the most prevalent fats, making up 95% of the fats you eat. There are other lipids, too. We’ll drop the chemistry for these ones.

Phospholipids

Phospholipids are soluble in both water and fat, which makes them a great emulsifier. You’ll see these as food additives as lecithin. Phospholipids are the main structural component of cell walls in our body. The best food sources of these kinds of fat are eggs, peanuts, liver, soybeans, and wheat germ.

Sterols

Sterols make up bile acids, sex hormones, adrenal hormone, and Vitamin D. Both plants and animal products contain sterols. Cholesterol is only found in animal-derived foods like meat, eggs, and dairy products. Many people try to avoid cholesterol because of its ability to build up fatty plaque in the arteries, but it is the basis for the other compounds listed earlier, so it’s necessary in small amounts. Plant sterols ca inhibit absorption of cholesterol, and so a diet high in plant-based foods is a good idea to lower blood cholesterol.

We’ve heard of “good cholesterol” and “bad cholesterol”, but what the heck does that even mean? Well, here’s where a little biology comes into play. Since fat and water repel each other (like how you have to shake up a bottle of salad dressing), fat needs a little help being transported through our bloodstream, which is mostly water. Proteins come in acting as taxis for the molecules of fat, and together they are called a lipoprotein. Here’s where “good and bad” cholesterol come in.

Lipoproteins are distinguished based on their density. “Good” cholesterol is a high-density lipoprotein (HDL), while “bad” cholesterol is a low-density lipoprotein (LDL).  There’s even very-low-density lipoproteins, but that’s not important for our purposes. LDL’s purpose is to circulate the bloodstream with cholesterol and the other fats, making it available to cells that require fat’s energy. HDL’s purpose is to circulate the bloodstream, collect cholesterol, and take it away for disposal. As well, HDL have anti-inflammatory properties! Basically – LDL increases the risk for clogged arteries (and heart attack), and HDL lowers the risk.

Whew! The chemistry is over with!

If you’ve suffered through all of that science with me, kudos! I don’t want to get too complicated here – Salt and Skillet is all about simplicity, after all – but fats just seem to be a little more complicated than others, and deserve the extra love.

If you’ve skipped the science to get to the recap – no worries! It’s a lot to process, and frankly, not all that interesting (to most, I assume. I think it’s very interesting, but that’s why I’m writing about it!).

So, what is it that fats do for my body, again? Glad you asked! Fats provide energy for our cells, make up the cell membrane of our cells, transport fat-soluble vitamins, are the basis of necessary acids and hormones, and help our body make Vitamin D! They’re also the vehicle through which fat-soluble vitamins are absorbed from the food we eat. They’re awesome!

Where can I find fats in my diet?

Fats are found in both plant and animal foods! Of course, you’ll find them in anything deep-fried, where the food literally takes a fat bath, and baked goods, but let’s look at the more wholesome sources of fat:

  • Meat, poultry, and seafood – some sources are more lean than others, with fish and chicken being your best choices.
  • Dairy – the percentage of milk determines the amount of fat – Skim (0%), 1%, 2%, and Whole (3.25%). Yogurt and cheeses, too.
  • Eggs – all of the fat is found in the yolk of the egg, as well as half the protein!
  • Legumes, nuts, and seeds! Nut butters are high in fat – portion them out instead of just eyeballing!
  • Vegetables, such as avocado and olives. Most vegetables are very low in fat, if they have any at all.
  • Grains – as long as they’re whole grains, you’ll get juuuuust a little bit of good fats along with those carbs.
  • Don’t forget about your cooking oils and butters.

Healthy fats are found in eggs, dairy, oils, and nuts.

So, what do you think? For being a word with a strong, negative correlation . . . fats are actually pretty good! Did I mention they taste good, too?

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