Macronutrients Part III - Fats
By Chris Zinn
Welcome to part III of this series on Macronutrients! If you didn't get a chance to read parts I and II, then check them out here:
Macronutrients make up the lion's share of our diet, and they also are major topics of discussion and debate when it comes to the efficacy of one diet over another. In this series, I've tried to give you a little more understanding of each macronutrient, as well as some information on why you need them all!
It's important to understand protein, fat, and carbohydrates. It's important to understand how they can and should fit in a diet. It's also important to know how to avoid unhealthy macronutrient intake in any category.
My goal has been to give you some more background and understanding throughout this series on each macronutrient so that you can make the right choices about your diet based on your unique circumstances.
Today, we round out the series with fats.
The only macronutrient that has taken more heat than carbohydrates is fat. This is because many people confuse dietary fat with body fat, and they assume that any fat in their diets will contribute to more unwanted body fat.
However, this isn't really the case, as you could eat a diet of 90% carbohydrates and still gain weight if your caloric intake consistently surpassed what you burned for the day.
Likewise, you could eat a high-fat diet and actually lose weight if you ate the right amount.
This lack of desire to gain fat, though, has spawned those low-fat/no-fat diets that are almost impossible to stick to over the long-haul, not to mention that they can be at times dangerous.
But let's dive a little deeper into what fats are, why they're essential, and why they've made such a bad name for themselves over the years.
What Are Fats?
Fats are organic molecules made up of carbon and hydrogen joined together in long groups called hydrocarbons. How these hydrocarbons are arranged determines the fat type.
Fats are really part of a much bigger group called lipids. Lipids are a broad category of molecules that are all fat-soluble (rather than water-soluble). Under the category of lipids we have substances such as:
fats and oils
Because lipids make up such a broad category, as a group they can do lots of different things and be classified in many ways.
For example, lipids offer energy storage, insulation, and padding for internal organs as part of your body fat. However, a completely different group of lipids makes up the contents of your cell membranes.
When broken down into its building blocks, the most basic version of a lipid is a fatty acid. You can compare the fatty acid and lipid to the amino acid and protein. Just as the amino acid is the building block of a protein molecule, so also a fatty acid is the building block of a lipid.
Fatty acids have different jobs depending on their length. Specifically, they can be grouped into:
Short-chain fatty acids (SCFA)
Medium-chain fatty acids (MCFA)
Medium-chain triglycerides (MCT)
Long-chain fatty acids (LCFA)
Very long-chain fatty acids (VLCFA)
Saturation of Fats
A fatty acid is composed of hydrogen and carbons. When they are joined together it is called a hydrocarbon chain.
Additional hydrogen atoms can bond to the hydrocarbon chain if there are spaces available. This availability of space for hydrogen atoms to join the chain is known as its saturation (i.e., saturated vs. unsaturated fats).
Whether or not the hydrocarbon chain is full or contains empty spaces determines if the fatty acid is saturated or unsaturated.
Think of this scenario as a parking lot filled with cars. In one row, all the vehicles are hydrogen atoms making up the hydrocarbon chain.
A row with some spaces left in it is not saturated and would be classified as an unsaturated fatty acid. Whereas a row of cars that has every spot taken would represent a saturated fatty acid.
Wherever an unsaturated fatty acid is missing hydrogens, there is a "kink" causing the acid to be slightly bent. Conversely, saturated fatty acids are rigid since they have every spot filled up by a hydrogen molecule.
This allows the saturated fatty acids to pack together tightly, and because of this, they are usually solid at room temperature. Unsaturated fatty acids don't fit together nicely because of that kink and are mostly liquid at room temperature.
Most dietary sources of fat are made up of both types of fatty acids, rather than just one or the other.
For example, some people think that eggs are bad because they contain saturated fat. However, eggs are made up of primarily unsaturated fat (~43%) compared to saturated fat (~39%).
Is saturated fat bad?
Saturated fats are commonly touted as unhealthy or blamed for the cause of some diseases. However, this is an overly simplistic view of things.
Suppose you have high cholesterol or cardiovascular disease. In those cases, saturated fats may not be the best choice for your diet. Still, certain types of saturated fats can actually lower LDL levels. Hence, the effects of these fats are more complex than just being "good" or "bad."
Generally, natural sources of saturated fats will be less likely to contribute to chronic disease than their "man-made" counterparts. This is simply staying consistent with our theme throughout these blog posts: opt for the whole, minimally processed foods rather than the highly processed foods.
Even foods that contain saturated fats, when minimally processed, are much less likely to contribute to chronic diseases like cardiovascular disease.
Are there any fats that are unanimously considered harmful? Yes… Trans fats.
Earlier, we talked about how the configuration of certain fats define how they behave and how they are identified.
The saturated fats were straight, and that caused them to lay flat and be solid at room temperature. The unsaturated fats had a "kink," which allowed them to be a liquid at room temperature.
However, there is a process called hydrogenation in which unsaturated fat is bombarded with hydrogens, artificially filling in the empty spots and causing it to become solid at room temperature. Hence, it more closely resembles saturated fat.
This type of fat is highly processed, and it is known as “trans fat”.
Certain types of trans fats are naturally occurring, but for the most part, trans fats are derived through artificial processes.
Eating a lot of artificially produced trans fats can:
lower HDL (good cholesterol)
suppress the excretion of bile acids
increase our own total cholesterol production
compete with essential fats for transport into the cells
create and worsen essential fatty acid deficiencies.
Okay, so people created a terrible fatty acid that really does nothing positive for your body.
Mainly because industrial hydrogenation is suitable for commercial food production. It keeps all those snacks on the shelves "fresh" much longer and increasing product shelf life is good for business.
Essential fatty acids
Now, just like there are some amino acids that are essential (meaning we must get them from our diet because we cannot produce them internally), there are some essential fatty acids that must be consumed and are not produced by the body. 2
The two types of essential fatty acids are:
Omega-3 fatty acids
Omega-6 fatty acids
The most important omega-3 fatty acids are α-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA).
Plant sources such as flax, chia, hemp, and walnuts are rich in ALA.
Marine sources such as fatty cold-water fish (and fish oil) and algae (the original omega-3 sources for fish) are rich in EPA and DHA, widely recognized as the most beneficial omega-3 fats.
Human breast milk is also an essential source of EPA and DHA for developing infants.
Omega-3 fats are considered anti-inflammatory. They tend to promote eicosanoids that do things like:
dilate (i.e., open) our blood vessels to improve blood flow
prevent blood coagulation and clumping
dilate our airway
support our immune system
Three critical omega-6 fatty acids are linoleic acid (LA), gamma-linolenic acid (GLA), and arachidonic acid (AA).
Omega-6s are considered pro-inflammatory. They promote eicosanoids that do the opposite of what omega-3 eicosanoids do. For example, they:
constrict blood vessels
cause blood clotting
constrict our airway
All these processes may sound unhealthy to the body, but your body needs them to heal from sickness or recover from training.
Why are dietary fats essential?
Dietary fat has six significant roles:
It provides us with energy (indeed, it's the most energy-dense macronutrient).
It helps make and balance hormones, particularly our steroid hormones (such as sex hormones and corticosteroid hormones).
It forms our cell membranes.
It forms our brains and nervous systems.