It’s no secret that fats have a bad reputation lately, and are generally discouraged by most in the medical community and nutritional fields. Most foods that are considered “healthy” by the majority of Americans carry a “low-fat” label. I just had a friend tell me she was going on the slim-fast and Special-K diet (cringe) because it was “low-fat.”
I could understand the fat-phobia if perhaps fat had been linked to weight gain or incidence of disease.. or maybe if America’s obesity epidemic had lessened since the low-fat craze… or maybe if eating a low fat diet actually caused long-term weight loss (anyone tried it?). The sad fact is that most people accept the hypothesis that fat is bad without understanding the biology behind the body’s need for fat.
Chemically, all fats are made up of varying numbers of hydrogen, oxygen and carbon arranged in different orders. Each carbon atom is bonded to two other carbon atoms, and the more carbon atoms there are in a given fatty acid, the longer it will be. Fatty acids with longer chains typically have a higher melting point and yield more energy per molecule when metabolized.
If a fat has each carbon atom bonded to two hydrogen atoms, it is considered a saturated fat, because each carbon molecule is “saturated” with hydrogen. These fats tend to be solid or near solid at room temperature. A monounsaturated fat has carbon bonded to only one hydrogen and double bonded to another carbon. A polyunsaturated fatty acid has more than one of these double bonds. A trans fat (transaturated fatty acid) is an artificially manipulated version of an unsaturated fat and is one type of fat that actually has been linked to disease. Thanks to wikipedia:
There are two ways the double bond may be arranged: the isomer with both parts of the chain on the same side of the double bond (the cis-isomer), or the isomer with the parts of the chain on opposite sides of the double bond (the trans-isomer). Most trans-isomer fats (commonly called trans fats) are commercially produced rather than naturally occurring. The cis-isomer introduces a kink into the molecule that prevents the fats from stacking efficiently as in the case of fats with saturated chains. This decreases intermolecular forces between the fat molecules, making it more difficult for unsaturated cis-fats to freeze; they are typically liquid at room temperature. Trans fats may still stack like saturated fats, and are not as susceptible to metabolization as other fats.Now that we got the biology out of the way, what does this mean in the dietary world? While fats have been demonized lately, they are sources of essential fatty acids and are necessary in absorption of vitamins A,D,E, and K, maintenance of skin and hair and in proper cell function. Fats provide 9 calories per gram and are broken down into fatty acids and glycerol (a source of energy) once in the body. When a chemical or toxin enters the body and reaches an un-safe level, the body dilutes it or attempts to equalize it by storing it in adipose (fat) tissue. The problem here is that if you are consuming high levels of chemicals or toxins (not fats) you can store these in your body and they can reach high enough levels to cause disease.
The fat-hating in society today is not based on its ability to keep toxins in the body, but rather on it supposed ability to cause weight gain. While fat has been blamed for weight gain, nothing happens in a vacuum. To understand why excess fat can, in some cases, lead to weight gain, we have to understand what those cases are. The body is capable of breaking fat down into glucose and using it for energy, though this process takes more energy than just using any fructose or glucose already circulating in the blood. When we eat grains, processed carbs or even high levels of really sweet fruits, these are easier sources for the body to use for energy. Eventually, the body starts to prefer these easier sources of energy and through insulin and leptin resistance, doesn’t metabolize fat as effectively. Additionally, any access carbohydrates that the body doesn’t immediately use for energy is converted to fat to be stored for future energy. If you are constantly feeding your body quick energy in the form of carbs, it never taps into this stored energy (fat) and fat accumulates. Any extra fats consumed at that point are also stored as fat since the body is burning its quick and easy form of fuel from carbohydrates. In this way, it is much more logical to understand that excess carbohydrates, not excess fats, cause weight gain.
So what fats are we supposed to eat and what to avoid?
Saturated Fats
Found in foods like meats, coconut and avocado, these guys are absolutely vital to proper body functions. They also get most of the heat from the “low-fat” crowd. Saturated fats are necessary for absorption of certain vitamins, calcium uptake, immune function, and cell membrane structure.I recommend daily intake of saturated fats from meats, butter, coconut oil, coconut products, avocado, etc as the main source of fat for all my clients. Conventional wisdom would say they should all gain weight. In combination with a low grain diet, they all actually lose weight (except for the occasional person trying to gain weight) and notice some common benefits: increased tolerance to the sun (tan better), skin issues like acne or eczema clear up, drastically increased energy, absence of food cravings, and peaceful sleep. Enough to convince me!
Monounsaturated Fats
Of all the fats, these get the most acceptance in medical and nutrition communities today. Monounsaturated fats are found in varying levels in oils like olive, sunflower, sesame, flax, peanut, safflower, etc. These oils are not entirely made of monounsaturated fats but also have some levels of saturated and polyunsaturated fats. I recommend monounsaturated fats to clients in moderate amounts, but never heated to high temperatures as this can cause breakdown and free radicals. Speaking of free radicals….Polyunsaturated Fatty Acids
These are found in grains, soybeans, corn, peanuts etc. They are liquid even at cold temperatures, go rancid easily and break down into free radicals when heated. These are also the oils we most often heat to really high temperatures when we fry things like potatoes and grains. To re-cap we use these oils that are from unhealthy sources at temperatures that make them even more dangerous and then drop in even more of the same unhealthy substances (grains, corn, etc) to round it out. These are also the oils used in non-foods like margarine and Smart Balance (a stupid idea!).To add insult to injury, most of these oils go through a hydrogenation process that makes them last longer on the shelf, but makes them basically unusable to the body since we can’t metabolize them. Not only are they creating free-radical damage, but they don’t even provide any relevant source of nutrition or fat the body can metabolize.
You will see polyunsaturated fats under names like corn, cottonseed, canola, vegetable, soybean, peanut, etc and most of them often carry the title “hydrogenated” or “partially hydrogenated.” My general advice to everyone is to completely avoid these types of fats, especially if they have been heated.
The Omegas
You’ve probably heard of the Omega-3s and Omega-6s as they are finally starting to be understood by the medical community. Both are necessary to our bodies, but most people these days get them in a balance that is very unhealthy. In a perfect world, we would get a ratio of 1:1 of omega-6s and omega-3s, though I usually tell my clients they are doing well if they can get a 3:1 ratio. If kept within this balance, both are healthy and necessary for optimal body function. Seems reasonable, right? Most people in America today consume a normal ratio of up to 35:1 (omega-6 to omega-3), while some people consumer even higher ratios.Omega-3s are found in things like fish, nuts and types of algae. Omega-6s are found in grains, corn, and animals fed grains and corn. Unlike things like Vitamin D, which our bodies are capable or making, the omegas must be gotten from diet (thus the name, essential). The reason you often hear of people benefiting from supplementing Omega-3s is that with the distorted ratios we consume of these fats, taking additional Omega-3s helps balance the body’s need for both in a 1:1 ratio. For those of us not able to consume that perfect 1:1 ratio, supplementing omega-3s can help with brain function, inflammation, chemical balance in the brain, and energy levels. Omega-3s also contain the much-touted ALA, DHA and EPA fats that are now added to many foods. I get my omega-3s from dietary sources as much as possible and also supplement with Krill Oil to keep the ratio in balance.
Trans Fats
These are the one type of fat that completely deserves the heat it has been getting lately. That hydrogenation process that we mentioned earlier turns unsaturated fats into these much more dangerous trans fats by changing the placement of the hydrogen atoms in the molecule. These fats are able to be absorbed by individual cells and mess up the function of the cell. Studies connect these guys to heart disease, obesity, abdominal fat, diabetes, and certain types of cancer. Trans fats are one of my arguments against the “everything in moderation” idea, as they are not safe in any amount.As Trans Fats have gotten such a bad rap lately, scientists have cooked up an even more unsavory fat made by replacing part of the fat molecule with stearic acid. These “interesterified fats” are what allow snack makers to place that lovely “no-trans fat” label on their packaging. Don’t be fooled! Interesterified fats are just as dangerous, if not more so. The few studies they have actually performed on these guys show that they can alter metabolism (i.e. slow it down!).
As a recap: saturated fats from healthy meats, coconut, avocado and nuts are good. Monounsaturated fats are good as long as they are not heated. Omega-3s are vital to our body, especially because we eat them in improper ratios. Polyunsaturated fats, hydrogenated fats, trans fats and interesterified fats are actually dangerous and should be avoided.
No comments:
Post a Comment