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  • Siri DeMarche

Your Quick Guide to Dietary Fat

Updated: Jan 28

Hopefully by now we're all well aware that a low-fat diet is really dangerous. You need fat for the optimal biochemical functioning of your body. Not all forms and sources of fat are equal. Some are really great for you, while others...not so much. Unfortunately between diet fads, social media hearsay, mainstream media, corporations with an agenda, and conventional misnomers, the labeling of dietary fat sources as "good" or "bad" has been sorely misguided and has put a lot of people at risk for developing metabolic disease. Here is your quick guide to dietary fats to help you wade through all the noise (and help you understand why it's crucial that you get adequate amounts of it in your diet).


First, a little background. The notion that dietary fat should be avoided was, in part, due to a campaign from the 1960's which paid scientists to contribute heart disease to saturated fat, and not sugar. Saturated fat is fundamentally necessary to your health and longevity! Getting adequate amounts of quality dietary fats is crucial to brain functioning, optimal hormone balance, keeping you full, strengthening & rebuilding cell membranes, warding off disease, and so much more.


Why is Fat so Important?

Your brain is 60% fat. It is the fattiest organ in the body, and as such needs plenty of quality fats to keep it functioning optimally. Brain cells are covered in a fatty insulation layer called myelin. This insulation layer allows for effective communication between brain cells via electrical signals (like an insulated electrical wire). When your myelin is weak, communication between brain cells deteriorates. Saturated fat feeds myelin, keeping it strong and intact. Fat is metabolically advantageous because it does not trigger the release of insulin like glucose does. And because insulin is a hormone that controls body fat storage, high (quality) fat diets can be a great option for those looking to lose weight and for those at risk for developing metabolic disease (i.e. diabetes). Fat is vital for keeping your cells healthy. Two layers of fat, called your lipid bilayer, give your cells structure and controls what enters and exists the cell. Fat is also essential for making sex hormones, like estrogen and testosterone. When you do not get enough dietary fat, these hormones are not balanced optimally. In addition, fat releases leptin. Leptin is a hormone that prevents you from overeating by telling your brain that you have eaten enough to satisfy your energy needs. Because dietary fat helps keep you satisfied and able to maintain steady blood sugar levels, you will not be distracted with cravings, energy crashes through out the day, or left hungry soon after eating a meal. Some vitamins like A, E, D, and K are fat-soluble. This means that they need fat to be absorbed and properly assimilated in the body. Quality fats carry these vitamins through the bloodstream into the liver and body fat, where they are stored until the body needs them.


For WAY too long has a high-carb, low-fat diet been toted has "heart healthy." This is a dangerous narrative (for all the reasons above), and especially because Americans continue to gain weight and rates of heart disease continues to skyrocket. When you eat too many carbohydrates and avoid fat, you raise your blood sugar and increase your risk of coronary artery disease. Research also shows the antidepressant effects of a diet full of quality fat. But how much dietary fat should you be consuming? Your weight, how much you exercise, your genes, and hunger levels all help determine exactly how much dietary fat is perfect for you.


Different Types of Fats

Not all dietary fat affects your body in the same way, and getting the proper ratio of different types of dietary fat is paramount. When considering dietary sources of fat, there are several factors to take into account because each type of fat behaves differently in your body. Most of the dietary fats that you consume are comprised of triglycerides. Triglycerides are made up of glycerol (an alcohol) and fatty acids. Most of the structural differences in fats are due to their chemical structure. Fat molecules have large bodies and thin tails. The length of the tail determines how the fat is processed in the body. The stability of a fat (how easily it spoils and creates free radicals in your body) also determines how the fat behaves in the body. There are four different types of dietary fats, they are: saturated, monounsaturated, polyunsaturated, and trans fats.


Saturated Fats

Saturated fat has a terrible reputation. This is, in part, due to a scientist named Ancel Keys who published research claiming that it caused heart disease. The theory was that the saturated fat in butter, red meat, and egg yolks increases cholesterol, which then builds up in the arteries and blocks the flow of blood to the heart. While this theory has been debunked (turns out that Keys had manipulated the research) and later studies have shown that saturated fat does not raise LDL in the body, saturated fat is still seen as an artery-clogger. Saturated fat is the most stable fat. The more stable a fat is, the less likely it is to be damaged by oxygen (oxidized). Oxidized fats accelerate aging, cause inflammation, and weaken cell membranes (this increases your risk for heart disease, stroke, and cancer).


In a saturated fat molecule, there are no open spaces, aka "binding sites," where a free radical can enter and damage the fat.


*Saturation refers to the number of hydrogen atoms and double bonded carbon atoms in a fatty acid. A "saturated" fatty acid has only single-bonded carbon atoms and the maximum number of hydrogen atoms. The fatty acid chain is saturated with hydrogen atoms. Whereas an unsaturated fatty acid contains at least one pair of double-bonded carbon atoms in the hydrocarbon tail, so there are fewer hydrogen atoms.


Ex. Grass-fed butter is a great source of saturated fat because it's plentiful in antioxidants, fat-soluble vitamins, and fatty acids like conjugated linoleic acid (CLA) and butyrate (a short-chain fatty acid that strengthens the gut and brain). Note: grass-fed butter is different from conventional butter and only grass-fed butter delivers these benefits.


Because fatty acids are easily damaged by heat, oxygen, and light, the more stable it is, the less likely it is to spoil. Saturated fats are the most stable and less likely to break down at high heats. This means that they are the best to cook with because the heat will not damage the fat, thus preventing carcinogens from forming.


Monounsaturated Fats

After saturated fats, monounsaturated fats are the second most stable because there is only one binding site where a free radical could enter. Monosaturated fats are liquid at room temperature, whereas saturated fats are typically solid at room temperature.


Ex. Oleic acid is a commonly found monounsaturated fat that protects the heart. Some foods rich in monounsaturated fats are olives, avocados, eggs, almonds, and pasture-raised pork (again the "pasture-raised" is very important here!).


Polyunsaturated Fats (PUFAS)

Polyunsaturated fats are the least stable of the bunch. This means that they are the most easily oxidized, making them the most inflammatory. Polyunsaturated fats have many binding sites open, making them vulnerable to damage.

Eating too many PUFAS can lead to severe health problems. PUFAS are typically found in canola, cottonseed, corn, peanut, safflower, soybean, sunflower, and other vegetable oils But it is too simplistic to simply say that all these oils are "bad." While lower-quality oils are usually genetically-modified using toxic solvents, two of most important types of fat are polyunsaturated. These are omega-3 and omega-6 fatty acids. They are both unstable, but are essential to your survival. Your body cannot produce these on its own and so you must get them from your diet. However, omega-3s and omega-6s do not benefit the body in the same way. The ratio between these two, as they exist, in your body is very important. Omega-6s cause inflammation, while omega-3s do not. A little bit of omega-6 fat is good for your brain, muscles, and blood sugar, but too much omega-6 fat will cause inflammation and damage your health.


The right ratio between omega-6s and omega-3s is crucial, because they compete for space in your body. The problem is that most people consume too many omega-6 fats and too little omega-3 fats. Ideally, you want to eat just enough omega-6s to get the benefits.


Ex. sources of omega-3s include wild salmon, sardines, anchovies, grass-fed beef, and pastured egg yolks. Walnuts, flaxseed, and chia seeds are also rich of omega-3s, but your body does not easily absorb fatty acids from plants.


There are different kinds of omega-3s.

-EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid):

These guys are long-chain fatty acids (they have at least 14 carbon atoms in their tails) and both come from animal sources. Most fish oil supplements contain a combination of EPA and DHA because their benefits complement each other. EPA and DHA are especially important for pregnant and breastfeeding women, because they are essential to building and strengthening a baby's brain.

-ALA (alpha-linolenic acid):

This is a short-chain fatty acid, meaning it has 6 or less carbons in its tail. ALA comes mostly from plant sources. Most animals convert it to DHA, because their bodies cannot use it. Humans can only convert up to 9% of ALA to DHA, so we must get our DHA from our diet (aka an animal source) for an optimally functioning brain and body.


Omega-6 fats are found mostly in refined vegetable oils, poultry, and some nuts and seeds. A little bit is necessary, but too much is dangerous. The most common form of omega-6 is linolenic acid, which our bodies convert into arachidonic acid. In access, arachindonic acid builds inflammation-promoting molecules. In small amounts, arachindonic acid is helpful to build cell walls.


Trans Fats

Trans fats are artificially made when hydrogen gas is added to vegetable oil to make it solid. These man-made fats are the worst type for your health and are found in highly processed foods like fried foods, margarine, and packaged baked goods. They're cheap to produce and extend product shelf life. Trans fats are the fats that negatively mess with cholesterol, are incredibly inflammatory, and increase your risk of stroke, heart disease, and diabetes. Trans fats can also affect your brain chemistry, causing depression and memory loss. According to the World Health Organization, more than half a million people die every year from heart disease attributed to trans fat. There are some trans fats that are naturally found in beef and dairy. These natural occurring trans fats do not pose the same health risks that artificial trans fats do.


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