Good Fats vs. Bad Fats
The simplest unit of fat is the fatty acid, comprised of a straight hydrocarbon chain terminating with a carboxylic acid group. The significance of the fatty acid is that it contains a polar, hydrophilic (water-loving) end, and a non-polar hydrophobic (water-hating) end, rendering fat molecules insoluble (or non-dissolving) in water. This property makes digesting fats more complicated, requiring specific enzymes and acids (bile) to be broken down and absorbed into the body.
Fatty acids are classified according to their chain length and number of double bonds. Saturated fats are long chain fatty acids with no double bonds. Unsaturated fatty acids are characteristically shorter in length (than the saturated fat), and contains at least one carbon-carbon double bond. Monounsaturated fatty acids contain only one carbon-carbon double bond (omega-9 fatty acids, and polyunsaturated fatty acids contain at least 2 or more carbon-carbon double bonds (omega-3 fatty acids). Triglycerides are the main storage form of fatty acids found in adipose tissue within the body.
Fats or lipids classify many different compounds. The major role of fat within any biological organism is to serve as insulation, protection, and energy storage. Dietary fat is the main storage form of energy beyond glycogen, can be found as triglycerides in the adipose tissue in all animals, and constitutes the cellular membrane (phospholipid bilayer) of all living organisms. All foods contain varying amounts and types of fat. Fat supplies the most concentrated source of dietary calories, accounting for 9 calories (units of energy) per 1 gram of fat. Due to it's complex structure and energy density, the human body favors fat storage over using it for fuel. Chronic consumption of excess dietary fat quickly becomes the stored fat on our bodies.
How much and what kind of fat in the diet will have a large impact on the health of an individual. The typical Standard American Diet (SAD) is riddled in large amounts of saturated fat, trans fat, cholesterol and omega-6 fatty acids, which increase a person’s risk for developing numerous chronic health problems including heart disease, diabetes, kidney and liver disease, cancer, obesity, thyroid disorder, autoimmune dysfunction, inflammatory diseases, and acne. For optimal health, it is best to take in limited amounts of good dietary fats, and to avoid a high fat diet in general.
Saturated Fatty Acids
Saturated fats are characterized by their ability to remain solid at room temperature, as well as their capacity to burn (oxidize) slower than unsaturated fatty acids. Long chain saturated fats are extremely difficult to break down in the human body, and are often the first to be stored as adipose (fat) tissue.
Sources of long chain saturated fatty acids are found almost exclusively found in animal products, like meat, cheese, butter, eggs, poultry, fish. Some plant foods do contain small amounts of saturated fatty acids (coconut, nuts, peanuts, palm kernal oil).
Coconut oil is a plant-based fat made of 100% short/medium chain fatty acids. It is the only recommended oil to use for cooking due to it's ability to burn clean and slow. It is also handled fairly easily by the body in terms of digestion compared to long chain saturated fats, such as butter.
Excessive intake of saturated fats can be extremely detrimental to health, as has been linked to elevated cholesterol (LDL and total), increased blood pressure, and abdominal obesity; all of which are all major precursors to heart disease, diabetes, hormonal and immune dysfunction, and cancer. It is recommended that saturated intake not exceed 10% of an individual’s total daily calorie intake, or less than 20 grams/day.
*Cholesterol is not an essential dietary component; it is manufactured by liver cells and extrahepatic tissue (approximately 1g/day). Dietary cholesterol directly contributes to elevated total cholesterol and LDL, predisposing an individual to heart disease. The American Dietetic Association recommends a total cholesterol intake of less than 200 mg/day.
“Trans” fatty acid is the classification denoted to a fatty acid that has undergone the process of hydrogenation. Hydrogenation is a chemical process in which hydrogen bonds are infused into an unsaturated fatty acid (such as vegetable oil), changing its natural cis-configuration to a trans-formation. A trans-bond will allow the fatty acid molecule to extend into a linear shape (as opposed to a U-shape), rendering the trans fatty acid to be extremely stable at room temperature. This quality allows food products containing trans fats to have an extended shelf life.
Trans fatty acids include partially hydrogenated fats and oils such as margarine, shortening, vegetable (frying) oils, and spreads. Trans fats are typically found in packaged, processed, and fast foods. Examples of trans fat containing foods include cakes, cookies, muffins, margarine and other vegetable oil-based spreads, crackers, doughnuts, pizza, French fries, fried foods, and chips. The average American consumes an estimated intake of 8.1 grams of trans fat per day, found in foods consistent with the Standard American Diet (SAD). Studies have indicated that trans fatty acids have the ability to raise total cholesterol and LDL levels, and decrease HDL levels. Any individual that consumes food items containing trans fat are at an increased risk for developing heart disease, diabetes, hormonal imbalances, and cancer.
Unsaturated Fatty Acids
Unsaturated fatty acids are found predominantly in plant foods, and include both monounsaturated and polyunsaturated fatty acids. These fats are typically liquid at room temperature, and oxidize (degrade) quickly when exposed to light and heat. Unsaturated fatty acids become toxic when cooked, so it is best to use them cold as condiments to cooked dishes and salads. Monounsaturated fatty acids are found in avocado, olives (olive oil), almonds, peanut butter, nuts, seeds, and most plant oils (sunflower,sesame, canola, and safflower). Polyunsaturated fatty acids are concentrated in foods like hemp seeds, chia seeds, flax seeds, but are also found in smaller dosages in green leafy vegetables and fruits.
Polyunsaturated fatty acids include the essential fatty acids; linoleic (omega-6) and alpha-linolenic (omega-3). Essential fatty acids cannot be synthesized by human cells so they must be provided by the diet. Both omega-3 and omega-6 fatty acids exert major roles functional roles in growth and development, particularly of the brain, heart, skin and hair, bone, immune function, metabolism, reproductive organs. Omega-3 fatty acids exert natural anti-inflammatory properties, while omega-6's tend to be pro-inflammatory when taken in excess. The SAD diet typically contains up to 25x more omega-6 fatty acids compared to omega-3's, promoting widespread inflammation throughout the body. The ideal dietary ratio for the essential fatty acids is 1:6, omega-3:omega-6.
Foods high in omega-3 fatty acids include fruits, vegetables (especially leafy greens), flax/hemp/chia seeds, walnuts, and some whole grains. Omega-6 fatty acids can be found in mostly in nuts/seeds and their oils, corn and corn products, as well grains (especially processed and refined). Gamma-linolenic acid another type of fatty acid created from linoleic acid (omega-6), and has been shown to reduce inflammation. Sources of gamma-linolenic acid include evening primrose oil, borage oil, and black currant seed oil.
Omega-3 fatty acids have become very popular due to their anti-inflammatory properties and heart-health benefits. The long chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are synthesized from the short-chain, alpha-linolenic acids (omega-3s). EPA and DHA are necessary for both immune, heart, and brain health.
High fat diets like the Atkins diet, Paleo diet, and standard American diet are very damaging to a person’s health. These diets recommend consuming high levels of fat, including both saturated fat and cholesterol. Whenever dietary fat is consumed in excess of need, it is first converted directly to adipose tissue, until conditions are right for the storage fat to be burned for fuel. In the instance of insufficient carbohydrate/calorie intake, such as with high fat/protein, low carbohydrate diets (Atkins and Paleo), fat and protein become the primary fuel source for the body. This energetic shift causes the metabolic machinery of the cells to switch to a mode known as gluconeogenesis, in order to create glucose (fuel) from non-carbohydrate substrates (fat, protein). The biochemical process of converting fat molecules to fuel is extremely energy demanding and inefficient compared to glycolysis (simple sugar burning). The physiological consquence of converting fat to fuel results in an overall decrease in metabolic rate (similar to starvation), the ketosis (toxic by-products of fat metabolism), malnutrition, and chronic dehydration. While these diets may result in short term weight loss (mostly water weight), they are not sustainable long term health and can result in organ failure (kidney/liver), depression, hypothyroidism, weight gain, heart disease, diabetes, and cancer.
Low fat diets are the most ideal for optimal health and vitality, but that doesn’t mean plant-based fats should be excluded from the diet. It's important to focus on consuming plant fats as is found in fruits, vegetables, nuts, and seeds as opposed to oils. Studies have shown that overtly fatty plant foods consumed in their whole, fresh state, exert thermogenic properties due to their high antioxidant, fiber, and phytochemical content (check out this video). Nutritionally, plant fats take priority over animal fats due to their lack of saturated fat, cholesterol, and trans fat. Whole plant fats also contain more nutrients, fiber, less total fat, higher amounts of omega-3 fatty acids, and more antioxidants per gram consumed compared to animal fats. Keep in mind also, that ALL foods contain some amount of fat. The chart below shows the varying percentages of fat in the most commonly consumed foods.
· Lean Beef- 30% fat
· Skinless chicken- 23% fat
· Cheese- 60-80% fat
· Butter, margarine, oils (including vegetable)- 100% fat.
· Grains, beans, fruits, vegetables- <10% fat
Only approximately 2% of total daily calories are required to fulfill essential fatty acid demands within the human body, which is enough to maintain health, hormone regulation, as well as provide the parts necessary for protection/insulation. The American Dietetic Association (ADA) recommends a total fat intake less than 30% of total daily calories, with a saturated fat intake less than 10%. Although, many plant-based doctors recommend a dietary fat intake between 5-15% for optimal health.
For weight loss, pre-existing health conditions (heart disease, diabetes, cancer), or for optimal athletic performance (especially for endurance athletes), it is recommended to consume 5-10% of total daily calories come from fat, aiming for 30 grams or less of total fat per day.
The best way to figure out how much fat you are getting in your diet is to visit www.cronometer.com and start tracking your food intake TODAY! Most people have no idea how much or what kind of fat they consume on a daily basis. Cronometer will show the complete nutritional content of individual foods consumed as well for fat calories and grams of total fat, saturated fat, trans fat, mono- and polyunsaturated fatty acids, as well as the essential fatty acids. If you have any questions please leave them in the comments below!
Fat in your diet. http://www.pennmedicine.org/health_info/nutrition/fat.html
Gropper, Smith, Groff.Advanced Nutrition and Human Metabolism. 5th Ed.