Fat

WTF even is it?!

This Installment is Part II of a four part series on macronutrients. The first part was on protein¹, which is characterized by its properties utilized for, essentially making more, well, you. This Installment is on a macronutrient that is most often associated with making more you, but its main use, what its primary² physiological function is designed for, is an energy source. Only when consumed beyond our energy needs does it become a fuel storage material³.

Part II- Fat

What is fat?

A fat molecule, also called a triglyceride, is composed of a glycerol spine with three fatty acid tails attached to it- essentially, a glycerol molecule bonded to three fatty acid chains, where each fatty acid is a long hydrocarbon chain ending with a carboxyl group. Unlike protein, which has nitrogen, fat is comprised of carbon, oxygen, and hydrogen.

When humans consume fat, our bodies break it down into fatty acids which can readily be absorbed into the bloodstream. In the stomach, an enzyme called lipase begins breaking down the structure of fat. During its time in our digestive tracts, fat goes through a number of processes performed by the gall bladder, and intestines, etc, to ensure its absorption, not the least of which is its combining with water to form an emulsification that the body can use⁴.

There are four different types of dietary fat that we consume. They are saturated fat (SFA), monounsaturated fat (MUFA), polyunsaturated fat (PUFA), and trans fat (TFA). For practical purposes, fat is used by our bodies for energy, shock absorption, endocrine function, nervous system insulation, as well as nutrient absorption.

Why do I care?

Here we go. Let’s get into it. Let’s talk about the former, undisputed dietary boogieman of the 80s and 90s. If you were alive, you remember. Low fat food items were the absolute craze of the era. Food packaging often featured the grams of fat prominently displayed. Commercials boasted of the low fat content of their breakfast cereals⁵. It seems counterintuitive that the influx of low fat foods into the market coincides with one of the steepest parts of the slope of the obesity epidemic graph.

So why didn’t eating all that low fat food stem the spread of obesity? There are many reasons, but probably the main one is that all that fat in packaged food was replaced with sugar thereby maintaining, or often increasing, the calorie content of any particular food. So by making fat the singular nutritional pariah, all other metrics of dietary balance were neglected. People ate, ad libitum, all the low fat food they could cram into their carb holes.

Here’s why you care- low fat food didn’t stop the rise of obesity. Fat wasn’t, and isn’t the boogieman. There are no nutritional boogiemen⁶. Fat is an important energy source. Fat provides insulation. We need fat for our gorgeous hair and skin. Our endocrine systems rely on fat for hormone production. Fat soluble vitamins, A, E, and D are not readily absorbed in its absence. The membranes of all of our cells are largely comprised of fat. Our nervous system is lined with it. The stuff is important! You’re going to want some dietary fat. Here’s the thing with fat though- of the three main macronutrients, it’s the most energetically dense. There are more than twice the calories in fat than in protein or carbohydrates⁷. It is for that reason that it became the macro-non grata for that period of time.

Fat Sources

As with protein, fat sourcing is controversial. Remember there are basically four types of dietary fat: SFAs, MUFAs, PUFAs, and TFAs. We can eliminate the conversation surrounding TFAs because they are outlawed in the USA⁸. We'll focus on saturated, monounsaturated, and polyunsaturated fats. There’s a divide in the nutrition community regarding what’s considered ‘healthy’ fat.

The folks who tend to support a meat heavy diet claim that the relatively high amounts of saturated fat is of no consequence. Studies show that high amounts of saturated fat can cause an increase in LDL, (NIH). Studies also show that high LDL is an independent risk factor for cardiovascular disease (Johns Hopkins). Meat lovers claim that LDL can be off the charts so long as the other markers of metabolic health are favorable.

Another controversy amongst the nutrition community is the conversation surrounding seed oils, aka Omega-6 fatty acids, which are PUFAs. A few of the main ones are canola, safflower, sunflower, grapeseed, corn, soybean, cottonseed, and rice bran oils. Those that tend to demonize seed oils claim that Omega-6s are the main drivers of inflammation⁹. While there is a mechanism that supports this claim, meta analyses suggest that only .2% of Omega-6s gets converted to the substance associated with inflammation (NIH). We have to remember that correlation does not equal causation. In this case we have major packaged food companies selling cheap, hyper palatable, calorically dense, nutritionally bereft items. Seed oils are cheap. Companies love cheap, so they put these oils in EVERYTHING. One could make the leap that the seed oils in the foods is what’s causing inflammation. When tested, this simply isn’t the case (TUoQ). What’s more likely causing inflammation is excess body fat one accumulates from eating these foods. Adipose tissue releases cytokines which signal an inflammation response. Think of correlation’s relationship to causation this way: In the summer, ice cream sales always go up. In the summer, shark attack frequency also increases. Does that mean the boom in ice cream sales causes the increase in shark attacks? Obviously not. They happen in parallel. The same goes for many other things that show a relationship void of causality. With nutrition, mechanisms are important and need to be studied in order to ascertain whether there’s a causal relationship or a correlative one. But what’s far more important than specific mechanisms is outcomes. If we look at outcomes, seed oils appear to not be inherently dangerous.

Another type of PUFA is Omega-3 fatty acid. You’ve likely heard about these as they are generally accepted as the healthiest of fats. They’re associated with regulating blood pressure, blood clotting, and suppressing inflammation. In addition they’ve been shown to support all levels of cognition and brain function. Those in the longevity community swear by them for their overarching ‘healthiness.’

MUFAs are known for their heart health properties, blood sugar control, anti-inflammatory benefits, also their vitamin E content. You’ll notice that there is quite a bit of overlap with benefits and sources of MUFAs and PUFAs.

Here are some SFA sources:

• Beef

• Pork

• Butter

• Cheese

• Fried Foods

• Palm oil

• Hyper-processed meats

• Ice Cream

• Many pastries

• Cocnut oil

Here are some MUFA sources:

• Avocado

• Olives

• Dark chocolate

• Nuts

• Vegetable oil

• Cashews

• Peanuts

Here are some PUFA sources:

• Salmon

• Eggs

• Flax

• Mackerel

• Fish oil

To note: most, if not all, fat sources carry a combination of fat types. For clarity’s sake, I didn’t populate the lists with redundancies. Suffice to say that many food items have all three, SFAs, MUFAs, and PUFAs, in them. What’s important is the distribution. Read food labels.

How much do I need?

People should consume no more than 30-35% of their daily calories from fat. Of that, saturated fat should comprise equal to or less than 10% of daily calories. That leaves 20-25% from MUFAs and PUFAs.

For its health properties, many people take Omega-3 in the form of fish oils and other supplements. This can be helpful if you don’t like the foods that contain high amounts of it. I rarely see people reaching for that second helping of mackerel, for instance.

Conclusion

Fat is not the nutritional boogieman. Fat has high energy density, equal to nine calories per gram. It’s for its caloric density that it happens to be the culprit associated with weight gain and obesity. High amounts of SFAs can lead to high levels of LDL, which can lead to an increase in cardiovascular disease risk, so should be very limited. MUFAs and PUFAs are generally considered the healthy fats and should comprise most of your fat intake. Our bodies need fat for a host of important functions, like long term energy, hormone production, nervous system function, organ cushioning, nutrient absorption, etc. Fat makes food awesome. Use it. Don’t abuse it.

1. Learn about Protein here.

2. Fat has many functions beyond an energy source, such as providing cushioning for our organs and joints, hormone production, micronutrient absorption, etc.

3. Fat is still an energy source when stored as adipose. When stored in adipose, it’s potential energy.

4. The fat in our bodies is no different than the olive oil we cook with (or any other fat) when it comes to its affinity, or lack there of, for water. It is for this reason that fat needs to be emulsified to be absorbed.

5. Duh. Right? Obviously cereal doesn't have much fat. Well, not so obvious at the time. Food labels have only been mandated since 1990 (1994 is when all food packages to hit shelves had to have a label). Before that, only the savvy folks had any working knowledge of wtf they were eating. Seems crazy now.

6. Not quite true. Alcohol and trans fats (and likely something I’m leaving out) are unequivocally bad. They have no physiological or health upsides and notable, well understood, downsides.

7. Fat= 9 kcal/gram, Carb/Protein= 4 kcal/gram.

8. Partially hydrogenated oils are trans fats and are no longer found on food labels.

9. Seed oils contain high amounts linoleic acid which is converted to arachidonic acid in the body, which is a building block for inflammation.