Thursday, October 2, 2008

The Skinny on Fat... Fat Facts

In my last post, I wrote about the inevitability of consuming more fat when you eat low-carb.

Now, I'd like to talk about some fat facts. Types of fats, what makes fats different from one another, and where you find them.

When we speak of fat, we are really talking about fatty acids. All fatty acids are chains of carbon atoms linked together surrounded by hydrogen atoms. If a carbon atom doesn't have a hydrogen atom to bond to it will bond to a neighboring carbon atom. This is what defines the difference between a saturated fatty acid and an unsaturated fatty acid.

Fatty acids are grouped into three categories based on their chemical construction.
  1. Saturated fatty acids - SFAs
    All of the carbon atoms are bonded to hydrogen. Hence all the carbon atoms are "saturated" with hydrogen.
  2. Polyunsaturated fatty acids - PUFAs
    Several of the carbon atoms are not bonded with hydrogen and consequently bond with one another. So there are multiple "poly-" carbon atoms that are not saturated with hydrogen atoms "unsaturated".
  3. Monounsaturated fatty acids - MUFAs
    There are two carbon atoms which are not bonded with hydrogen, but are bonded to one another. So, there is one "mono-" bond between two carbon atoms which is not saturated with hydrogen "unsaturated".
Alright, we've laid out the basics for the difference between the fatty acids. Let's quickly cover some of the

Saturated fats tend to be more stable than unsaturated fatty acids. Saturated fats are less susceptible to spoilage and are less susceptible to oxidization when exposed to heat. They are solid at higher temperatures and have higher smoking points than unsaturated fats.

Unsaturated fats tend to be liquids at lower temperatures than saturated fats and may be referred to as "oils". They smoke at lower temperatures than saturated fats. Polyunsaturated fats are the least stable and are the most susceptible to becoming rancid or oxidizing when exposed to heat. If you say "why on earth do I care?". I'll tell you why. We've all heard of antioxidants, right? I can't go into all the science of all of this, but basically, things that oxidize are more likely to be carcinogenic , cancer causing, and antioxidants help protect us from oxidative damage. So, things that can cause oxidative damage should be avoided and things that protect us from oxidative damage should be consumed.

So, you're going to consume more fats on low-carb, you now know the difference between the different fats from a chemical standpoint, and you know a little more about the stability of fats in the face of heat and age. What you don't know is where you can find each of these fats.

A common belief about fats is that animal fats are largely saturated and that plant fats are largely unsaturated. Both statements are incorrect and misrepresent where different types of fats are found.

There is a lot of debate about the health of particular fats, but for now we will make only one assumption, because it is fairly widely accepted. The assumption is that monounsaturated fat, the primary fat in olive oil, is good for you. It may be good for your heart, it may do other good things for you.

Let's talk about the fats found in animals, then we'll talk about the fats found in plants.

First off, we'll take the most insidious of all fats, lard. I'll bet that if you ask anyone, they will tell you that lard is the stuff that heart disease is made of and it's probably worse than just about any other fat. Lard is rendered pork fat and it is obviously the worst of the worst. The fatty acid profile of lard is as follows (doesn't total 100% because of rounding):
45% - monounsaturated fat
39% - saturated fat
11% - polyunsaturated fat
So, the premise that animal fats are mostly saturated is apparently false. This means that the fat of bacon and pork chops and spare ribs is mostly monounsaturated, presumably heart-healthy fat. How about that?

If pork fat is mostly unsaturated fat, then surely beef with all that solid white fat must have nothing but saturated fats for you. Or does it? Check out the fatty acid profile of a delicious rib eye steak (doesn't total 100% because of rounding):
41% - monounsaturated fat
39% - saturated fat
4% - polyunsaturated fat

Personally I found it fascinating when I found out that beef fat too was mostly unsaturated fats. It seems far from what I thought I knew about types of fats and their food sources.

When we look at plants, we'd assume that those are pretty much unsaturated, but I think this deserves a closer look too.

Olive oil, purportedly good for your health and your heart. We'll assume it is for now, but maybe we don't know why. It's lipid profile:
14% - saturated fat
73% - monounsaturated fat
11% - polyunsaturated fat
So, this is clearly much higher in MUFAs than the animal fats we looked at, but far from free of SFAs.

How about coconut oil?
87% - saturated fat
6% - monounsaturated fat
2% - polyunsaturated fat

Corn oil?
58% - monounsaturated fat
8% - saturated fat
29% - polyunsaturated fat

Soybean oil?
58% - polyunsaturated fat
23% - monounsaturated fat
16% - saturated fat

So unsaturated fats do come from both plant and animal sources and the same appears to be true for saturated fats.

Animal sources appear to be largely made up of monounsaturated fats and saturated fats, with little polyunsaturated fat. Plants seem to vary widely in the percentages of saturated, monounsaturated, and polyunsaturated fats they contain.

I've gone on long enough with facts about fat, but I have a couple more things I should add. I hope you've read this far, because I think this will be a good lead in to the next post.

There is one food we were all designed to eat, indisputably. Breast milk. We don't all get it and I don't feel the need to entertain the debate over whether we need to or not, but the fact remains that it is indisputably the one food we were designed to eat and make us grow up strong and healthy. Before the advent of foods that were easy for infants and toddlers to eat, mothers used to nurse much longer than they do now. So breast milk was designed to sustain our growing youngsters for the first few years of life, providing much if not all of the essential nutrients for a healthy body.

I wonder what the lipid profile of breast milk is? Could it be:
48% - saturated fat
35% - monounsaturated fat
10% - polyunsaturated fat

So the lipid profile of the single most significant food in your life, which all humans were made to eat is mostly saturated fat, followed closely by saturated fat.

Finally, I'll leave you with this thought. We as humans have evolved to get our food from natural sources. Forgetting the rhetoric we hear from our doctors and government health officials for a minute, doesn't this then mean that we should endeavor to get our nutrients in the most natural form possible. Don't people say that it's better to eat broccoli than to take a vitamin, or better to eat an orange than drink orange juice?

If so, why not get your fat from natural sources that we have evolved to eat? Meats, eggs, fish, full-fat dairy products, olives, coconuts, palm are all great natural sources of fat. Corn, soy, rapeseed (canola) are not good sources of fat. They are not edible without processing and their fat content is too low such that they require large amounts of processing to extract their fat.

Next time, we'll talk some more about fat and some of the controversy over what kinds of fat you should eat and why.

Until then, we're trying to start a dialogue here, so help me out with some comments. I want to hear your thoughts. Positive, negative, neutral, share them all, please. As I said in my previous post, we need to talk about fat. We need to take some of the big scary out of this and get past the misconceptions, preconceptions, and get to the truth. It may not be what I have to say, but we won't know unless we talk about it.

If you have some good stuff to say about fat and what its done for you, that would be great too! I now have over 400 hits on this site, so I know some people are reading it. I'd love to hear more from you.


PS. Don't fear the fat! (Especially now that you know a little more about it)


Anonymous said...

This post came at the perfect time for me! Very informative. Spot on. There is nothing wrong with eating fats, the right kind of fats. What so many people value as the healthy stuff is over processed food. Remember the old days when Mom had a can of animal fat in an old coffee can on the stove for cooking? Why did that stop? Lewis Black has a bit about a man who ate fatback everyday. When asked why he didn't eat bacon the old man responded that bacon was too lean. :)

Alex said...

Thanks again Sadekat,

Glad to see you've read another of my posts.

I'm so with you on the value that so many put on processed food. It's pure craziness to me.

I started eating some fat back recently, there was a decent recipe for it over at Hyperlipid's Site check the listing on the side of the site or search for carnitas. They were tasty!

Bacon is surprisingly lean! It's almost as lean as eating chicken thighs with the skin or ribeye steak (lean and fat).

For more information about a high fat diet, Hyperlipid (Peter) has some very interesting information and is more scientifically inclined than I.

I recently started saving the fat from bacon for cooking eggs in the mornings.

Pretty soon, I'll write up a bit about how I've been eating. It's been interesting and I feel more energetic and mentally clear than I have for a while.


Former Donut Junkie said...

Well, it looks like the American people have once again been sold a bill of goods on the "fat is bad for you" theory. Somehow I've never really believed in it, even though I didn't have the science to back it up. Thanks for the excellent article Alex.

Alex said...

I couldn't agree more FDJ.

It never ceases to amaze me that people are so thoroughly committed to the idea that fat (in general) is bad for you and that they know what "good" and "bad" fats are.

My wife thinks I'm obsessed with fat, but I'm really just obsessed with fighting back against the misinformation we have all been fed.