OnePhatMan

I’d like to get down and dirty on a subject near and dear to many overweight people: dietary fat.

Fat is all around us, and can be found in most everything we eat. Americans are obsessed with fat these days for a couple of reasons. First, several studies have linked saturated fats (more on those in a minute) to coronary heart disease, the number one killer in this country. Second, prevailing thoughts are that dietary fat converts most easily into bodyfat, so an avoidance of the first should (following the logic) result in a decrease of the second.

First things first: don’t believe everything you hear. Fat isn’t evil, like you may have been led to believe, but certain kinds of fat are fairly unhealthful. Don’t avoid fats just to avoid them, know what you’re putting in your body and make wise decisions when it’s time to eat. Knowledge is power.

And now, fat 101…

A single molecule of fat is composed of three fatty acid molecules (strings of carbon and hydrogen) and one glycerol molecule. This molecule of fat is thus called a tri-glyceride. Fat takes three different forms, saturated, monounsaturated, and polyunsaturated. The idea of saturation comes from the amount of hydrogen atoms contained in a fatty acid. Most fatty foods contain quantities of all three types of fat, but generally one type is predominant.

Saturated fats have a hydrogen atom pair bonded to each carbon atom in the fatty acid. These fats are generally solid at room temperature (think butter, animal fat, and tropical oils), and are known causes of atherosclerosis—hardening of the arteries caused by cholesterol being deposited on arterial walls. Specifically, saturated fats elevate low-density lipoprotein (LDL) cholesterol levels in the blood. Chemically speaking, saturated fats are very stable.

Inside your body, it’s this stability that works against you, because that stability is what makes saturated fat able to stay solid at room temperature. Ingested fat becomes part of your liver membrane, and a lot of saturated fat in your diet leads to a stiffer, less flexible membrane. This membrane is responsible for filtering LDL out of your blood, but as it becomes stiffer, it’s less able to do its job properly, thus leading to increased LDL levels.

Monounsaturated fats are missing a single pair of hydrogen atoms and are liquid at room temperature (they’re also chemically unstable, which I’ll talk about shortly). Good sources of these fats are nuts, olives, and avacadoes. Following the same logic in the previous paragraph, monounsaturated fats make for a more flexible liver membrane which in turn makes for lower LDL levels in the blood. Further, monounsaturated fats appear to elevate high-density lipoprotein (HDL) levels in the blood. Many sources of monounsaturated fats are also rich in antioxidants (for example, olive oil is loaded with vitamin E), those beloved destroyers of free radicals.

In a nutshell, monounsaturated fats are very good for you.

Polyunsaturated fats are missing multiple pairs of hydrogen atoms, and like their monounsaturated friends, are liquid at room temperature and chemically unstable (as a matter of fact, they’re even more unstable than the monos because of the multiple pairs of missing hydrogen atoms). Good sources of polyunsaturated fats are safflower, sunflower, and corn oils, as well as several fatty cold water fish. Some studies have shown that polyunsaturated fats lower both HDL and LDL in the blood.

Still with me here? It’s about to get fun.

Most mono- and poly-unsaturated fats have the carbon atoms double-bonded to one another at the point(s) where the hydrogen atom pairs are missing.

Note: If you’re interested, chemists use the Greek letter ‘omega’ (it looks like our lower-case ‘w’) to designate the number of the carbon atom where the hydrogen is missing. Omega-6 fatty acids are missing a pair of hydrogen atoms at the 6th carbon atom, and omega-3 acids are missing them at the 3rd. Omega-3 fatty acids are super-good for you, but the average American is woefully deficient in these, instead getting mostly omega-6 acids. Good sources of omega-3 acids are flax seeds, flaxseed oil, salmon, mackerel, sardines, and other cold-water fish. There are also some good sources of omega-3 fats in supplements like Coromega and Udo’s choice oil blends.

This form of the molecule is called the cis-form, and is by far the most prevalent form these fats appear in naturally. The molecules have a specific shape because of this double-bonding, and that’s why they remain liquid at room temperature. These acids tend to oxidize at the point of the double bond when exposed to heat, light, and air, and turn rancid fairly quickly. If you cook with these, it’s a very good idea NOT to reuse the oil. Because these acids are so unstable and turn rancid so quickly, food (and I use that term loosely) manufacturers don’t like to use them in the products they make for our consumption.

Enter modern science.

Early in the 20th century, scientists discovered that if they took a perfectly good unsaturated oil, heated it to extreme temperatures (400+ degrees Fahrenheit), then used a metal (usually nickel) as a catalyst and forced hydrogen through it under extreme pressure, they could break that double-carbon bond into a single bond, changing the chemical structure of the fat. This process is called hydrogenation, and can be either partial (the oil is viscous, but still mostly liquid at room temperature) or complete (the oil is solid at room temperature, just like pure saturated fat). Hydrogenated oils are much more stable, and have a greater shelf-life than their original unsaturated counterparts. For these reasons, they’re loved by food manufacturers and some esitmates put the number of U.S. products containing hydrogenated oils at 60%.

The new form of the oil molecule, with the single carbon bond, is called the trans-form of the oil, and are what we call trans fatty acids. Transfatties do occur in nature, but not in great quantities, and they’ve been linked with a plethora of bad things in humans, including heart disease and cancer at the top of the list. Chemically, transfatties are similar to fully saturated fats, but pack a double whammy when we eat them: they not only have been shown to increase LDL in the blood, they’ve been implicated as decreasers of HDL.

Personally, I try to avoid them, though complete avoidance is nearly impossible (especially on junk food Friday) unless one reverts to totally preparing all foods from completely unrefined ingredients. Even with all the concern I have with what I’m putting into my body, I don’t like the thought of going to that length.

So now you have a basic understanding of dietary fat. Hopefully you weren’t too bored, and maybe you even learned a thing or two. If there’s one single point I want to get across, it’s this: fat isn’t evil, and a goodly number of fats are not only good for you, they’re essential to your survival. Don’t believe all the hype around “low fat” and “fat free” items. Heck, don’t even take my word for it—check it out for yourself.

Be informed, and be healthy.