The Truth About Fat!

I had a conversation yesterday with the wife of a co-worker at our company happy hour. She was very intrigued by my adamancy to avoid even one of the "loaded french fries" the table had ordered (Lays' "betcha can't eat just one" is a safe bet, 100% of the time), so the conversation shifted toward nutrition. She told me she had a friend who took a few nutrition courses in college and had informed her to avoid "all products with more than two grams of fat per serving." I fought the urge to ask about jelly bean and fluff sandwiches and said calmly, "well, that's a little outdated. I was happy to report my feelings about dietary fat and I find this the perfect opportunity to lay the low-fat myth to rest once and for all (at least for the 8 of you who will read this).

Your body needs fat. Yielding about ~9 kCal of energy per gram, fat is the most efficient source of energy for the body. Fats play a vital role in maintaining healthy skin and hair, insulating organs against shock, maintaining body temperature, and promoting healthy cell function. Vitamins A, D, E, and K are fat soluble and cannot be absorbed without it. Essential fatty acids (EFAs) are required for many processes, including the construction and maintenance of "structural" elements such as cell membranes, but the body cannot synthesize them, therefore they must be obtained through ingestion. In addition, fats can prevent overeating by prolonging digestion and triggering appetite suppressing hormones in the brain (see image). There is no proof that restricting dietary fat improves weight loss or even reduces heart disease risk. In fact, during the 1960s before the low-fat diet craze, Americans consumed about 45% of their calories from fat, and 13% were considered obese. Today, we consume about 33% of calories from fat, but an alarming 34% of us are obese.

With that said, not all fats are created equal. Some fats, including but not limited to trans fats, deserve all the bad press they've received over the years. All fats are composed of glycerol and both saturated and unsaturated fatty acids, but are generally characterized by their level of saturation.

All fatty acids contain an even number of carbons in a chain, from 4 to 28. As you can see, aside from the first carbon in the chain, a "saturated" fatty acid contains hydrogen atoms at all available bonding sites. "Unsaturated" fatty acids contain double bonds within the carbons, therefore there are less hydrogen atoms bonded due to now occupied bonding sites.

First, let me explain saturated fatty acids (SFAs). They are abundant in animal products and tropical oils and and have the unfortunate reputation of being "artery clogging." Truth is, they are not the monsters they are made out to be. SFAs are highly stable, due to the saturation of hydrogens, and they make up about 1/2 of cell membrane structure. They also improve immune function, and provide cholesterol which, contrary to popular belief, is required to establish proper membrane permeability and fluidity. For those looking to build muscle, you'll be happy to know that saturated fat boosts testosterone levels. Dairy fat, particularly from grass-fed animals, contains high levels of conjugated linoleic acid (CLA) - an isomer that has been shown to mobilize stored fatty acids for energy in mice, resulting in fat loss. Go ahead and have a nice ribeye and a big ol' glass of whole milk. 

The mono-unsaturated fatty acids (MUFAs) found in numerous oils, nuts, and avocados have one double bond in their carbon structure. They are granted the most approval by convention these days due to their "heart-healthy" properties. It should be noted, however, that these oils contain varying levels of MUFAs, and the rest is composed of a mix of SFAs and poly-unsaturated fatty acids (PUFAs). Canola oil, for example, contains 60% MUFAs, to olive oil's 75%.

I'm sure you can guess by now that PUFAs contain more than one double bond in the carbon structure. These are the real bad guys! The problem with PUFAs is they tend to oxidize due to instability, particularly when heated, resulting in plenty of free radical damage for you and yours. These are found in many grain products, soybeans, peanuts (say it isn't so!), and fish oil.

"But wait," you say. "I thought fish oil was supposed to be good for you!" Just relax...enter the EFAs - remember the ones your body can't produce? Omega-3 FAs are found primarily in fish, algae, flax, and nuts. Traces of Omega-3s can also be found in eggs of chickens fed these things and in grass-fed meats. These aid circulation by naturally thinning the blood, fight systemic inflammation, support brain function and even ease symptoms of depression, anxiety, and hyperactivity. Omega-6 FAs are important to skin integrity and renal function, to name a few. Good news is, they're all over the place - in corn (which is in EVERYTHING) and other grains, as well as grain fed live stock; bad news is, they spur inflammation if your 6:3 ratio is too high. 

Ideally, you should strive for a 1:1 ratio of Omega-6:Omega-3, but the typical western diet ranges anywhere from 10-30:1! All the inflammation, high blood pressure, depressed immune function is clearly a result of all the corn oil (46:1) and grain fed meats we eat. So what can you do? Invest in some fish oil (look on the label for a DHA+EPA concentration of at least 50%, otherwise you're getting a whole lot of filler, and aim for at least 1.5g of those total. I use NOW Foods Ultra Omega-3, which is 75% DHA+EPA.) It's also well worth the extra couple dollars to buy grass fed meats if you have access to them, especially if you're buying fattier cuts. Olive oil has a 3:1 ratio, which isn't that great, but consider that it's only 11% PUFAs and it becomes pretty insignificant, especially with the polyphenols that would probably reverse any damage caused by the problematic ratio. Olive oil gets the go-ahead.

Last AND least, the trans-fatty acids (TFAs). These are naturally-occurring MUFAs or PUFAs that have been chemically modified by adding hydrogens where they don't belong in order to improve stability (read: shelf-life). And the process works, so those Keebler cookies stay fresh on the shelves for months. The problem is, our bodies don't recognize the transformed fats and don't know how to eliminate them. TFAs are absorbed through cell membranes and basically wreak havoc on cellular metabolism. In short: TFAs cause fat gain. They are also associated with inflammation, atherosclerosis, diabetes, and immune system dysfunction. In the U.S., anything under .5g TFAs per serving can be labeled as 0g, therefore you must read your list of ingredients. If you see the word hydrogenated, run for the hills.

In conclusion, fat is your friend, as long as you maintain an appropriate calorie level for your goals. Be weary of PUFAs and eat at least 25% of your calories from fats, emphasizing coconut fat, egg yolks, grass-fed meat, full-fat dairy, olive oil, nuts, and avocados. Stay tuned; next time we'll address the "Fat vs. Carbs for energy" debate!