FAT: Is it Good or Bad?
Apr 02, 2013 08:26AM
By Tracie Leonhardt, DO
What is fat, and why are some good and some bad? This is a question that is frequently asked of me by my patients. We recently did a segment on my radio show on damaged fats, and I was not surprised to find many listeners were confused, especially since the science, medical and government communities have changed their stance several times over the last 30 years. So let’s look at some of the facts we do know in order to learn the truth about fat.
People have been so frightened about cholesterol and fat, they believe they must be avoided at all costs. However, cholesterol and fat are essential to life. They are used by the body as building materials for constant replenishment, and should come from dietary sources. Eating cholesterol and fat does not cause heart disease; it is the kind of damaged fats we eat that cause these issues.
Cholesterol is a type of fat that has many functions in the body. Fats and protein make up our cell membranes. Cell membranes function as the interface between the inside machinery and the outside of the cell. If the membrane is healthy, the traffic will flow both ways: nutrients enter the cell and waste byproducts exit. If the fats or fatty acids in the diet are "good" fats then the membrane will be elastic and retain its permeability, allowing traffic to easily flow in and out of the cell. However, if you eat too many "damaged fats", membranes will stiffen and the cell will have trouble exchanging nutrients for waste; you end up with a traffic jam.
When your body is made up of cells that are depleted of cholesterol, it is less efficient, which means your metabolism cannot function as it should. Cholesterol is also important to maintain normal function of various hormone systems and the immune system. Cholesterol is the structural material from which many important hormones are made, such as Vitamin D, DHEA, progesterone, testosterone, estradiol and cortisol (our major stress hormone). Cholesterol is essential for brain function and the stabilization of neurotransmitters such as serotonin and dopamine.
One of the main problems with patients eating fat is they equate dietary fat with body fat. But body fat is only one form of fat, and not necessarily derived from the fats that you eat. There are three kinds of fat in the body:
Structural fat is the class of fats used as building blocks within your body to make cells, hormones, and brain components.
Body fat is the reservoir of fat found in fat cells created from triglycerides, to be used as insulation and energy.
Dietary fat comes from animal and plant sources. Animal fats are composed of structural and body fat, while plant fats are oils that are made up of fatty acids. Dietary fats do not create fat on your body as fats do not stimulate insulin release and you need insulin to store fat. Fat cannot be stored without the presence of insulin because insulin is necessary to open the door to store fat in fat cells. Therefore, eating fat with sugar can lead to increased body fat.
Some symptoms resulting from a low fat diet include: brittle nails; carbohydrate craving; constipation; dry, limp or thinning hair; infertility; insomnia; fat gain around the middle; scaly, itchy skin; and mood disorders.
I have many patients that believe limiting dietary fat is the way to stay fit and healthy. How many people do we know that eat a fat-free diet and gain weight? A low fat diet works initially because if you reduce fats (the most concentrated energy source) from your diet, your body will use all incoming sugar and fat as energy which lowers overall blood-sugar and insulin levels. However, when you deprive your body of fat, you also deprive your body of protein, thus decreasing your lean body mass.
What is a Good and Bad Fat?
All fatty acids are made from long chains of carbon molecules bound together. A carbon molecule must bind to four other molecules. In these chains, carbon binds to two other carbons, one on either side, leaving two sides unbound. This positioning of the bonds determines the type of fat it is: Saturated, monounsaturated, or polyunsaturated.
Saturated fat is when the two sides are completely filled with hydrogen molecules—hence the term saturated.
Monounsaturated fat is when the whole fatty acid is missing two hydrogen atoms, one carbon will form a double bond with another carbon—hence one bond is not saturated
Polyunsaturated fat is when there is more than one site with the double bond — hence more than one bond is not saturated.
Your body can metabolize natural fats, but it cannot metabolize any type of damaged fat. Fats by nature are good, but what we have done to good, natural fats—deep frying and processing them from their natural state into oils—damages human physiology. Damaged fat molecules become cellular debris, clogging cellular compartments and in turn damaging cells.
Bad or damaged fats fall into three categories: Trans-fatty acids, oxidized fats, hydrogenated fats.
Trans-fatty acids, we have heard, are bad for you; but why? In nature, polyunsaturated fats occur in the "cis" configuration, meaning the hydrogen atoms around the double bond are on the same side, which is the desirable configuration. However, most polyunsaturated oils are processed out of their natural state by using very high temperatures (for example corn oil from corn). This process changes the natural "cis" configuration to an unhealthy "trans" configuration. "Trans" means the hydrogen atoms are now on the opposite side of the carbon double bond. These "trans" molecules are damaging to our bodies as we do not have the enzyme necessary to fully metabolize the trans-fat into energy. This is why polyunsaturated oils are easily damaged when placed at higher temperatures.
Oxidized fats are when oils are exposed to air and create free radicals! Oxidation can be seen visually as rancid fat and should never be eaten. Oxidation occurs easier at higher temperatures and through processing. Oils in their natural state contain antioxidants such as lecithin and Vitamin E, which are removed or destroyed during the refining process.
Hydrogenated fats are created when natural polyunsaturated oil has been altered by a chemical process that adds hydrogen molecules to the fat molecule. This process changes naturally occurring oils, which are liquid at room temperature, into solid fats. An example would be margarine from corn oil. The hydrogenation process creates new chemical structures as well as those unwanted trans-fatty acids. Margarine and shortening are two of the most damaging fatty substances you can eat.
Some basic guidelines for avoiding damaged fats are to avoid food cooked at high temperatures such as fried foods and charbroiled. Whenever possible eat your healthy fats, such as olive oil and avocado oil, in their uncooked natural state. Slow cook your food at lower temperatures. You need some good fat in your diet for your cells to be healthy.
Dr. Tracie Leonhardt is Medical Director of Peaks of Health Metabolic Medical Center, and is board certified in anti-aging and regenerative medicine and emergency medicine. She can be heard Tuesdays and Wednesdays on her radio show on 1110 am. Peaks of Health is located at 7600 Bryan Dairy Road, Suite D, Largo. Call 727-826-0838 or visit PeaksOfHealth.com. See ad page 10.
References: Grundy, Scott "Comparison of Monounsaturated Fatty Acids and Carbohydrates for Lowering Plasma Cholesterol" NEJM 314.12 745-48.
Kinsella, J.E. "Metabolism of Trans Fatty Acids with Emphasis on the Effects of Trans, Trans-octadecadienoate on Lipid Composition, Essential fatty acids and Prostaglandins: An Overview" The American Journal of Clinical Nutrition 34 (Oct 1981): 2307-18.
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Sinatra, Stephen; Roberts, James. Reverse Heart Disease Now. Wiley and Sons 2006
Wilson, Jean D., Williams Textbook of Endocrinology. WB Saunders.