The Good, Bad, and Ugly Truth About Fats

Diet culture has really run the gamut when it comes to trends on fat consumption. We’ve heard, “eat no fat,” “only eat unsaturated fat,” “animal fat is good as long as its organic,” “as long as you’re keto, fat doesn’t matter,” and so on and so forth. What are we to do with all of this contradictory diet advice?

But, don’t fall prey to diet paralysis caused by conflicting information and fad diets just yet. Believe me, I’ve been there. As a Dietitian and a Physician Assistant, even I have been overwhelmed by the amount of information being thrown at us regarding diet and health. My goal here is to give you enough scientifically backed information to make healthy decisions moving forward.

So, let’s break it down a little bit and go back to basics. What do we KNOW to be true about fats? What are they, how do we handle them once they’re in our body, and what are the most comprehensive studies telling us about fat consumption on diseases and longevity?

Fair warning, this article dives deep into the science of fats. I want you all to be informed and empowered to understand what you are putting into your body. After all, we are what we eat!

What IS Fat?

Fat is a type of lipid. Lipids refer to molecules found in food that do not dissolve in water. Think about how oil floats on top of water instead of mixing in. There are a few different types of lipids, but for our purposes today, I’ll be talking mostly about fatty acids (most commonly found as part of a triglyceride – three fatty acids held together by a glycerol molecule) and cholesterol.

When we say “fat,” we’re almost always referring to triglycerides and fatty acids. Simply put, dietary fat refers to a specific type of molecule found in food. I’ll spare you the biochemistry details, but just know that fats are made up of chains of carbon bonded together. The chains of carbon differ in length, which gives us our short-, medium-, and long-chain fatty acids. Fats also differ by the types of bonds they have, which classifies the fat by type of saturation: monounsaturated, polyunsaturated, saturated, or trans-fat.

When all the carbon molecules are saturated with a hydrogen (stay with me), the molecule lays flat, and the chains of carbon stack tightly on top of each other. This creates a solid substance at room temperature, such as butter or the fat you see on steak or bacon. Most soluble fats come from meat, dairy, coconut and palm oil, and hydrogenated fats in processed foods.


When the carbons create a double bond (because the chain isn’t fully saturated with hydrogen), the molecule creates a bend, or kink, and the chains of carbon do not lay flat and instead create a less dense, more liquid substance, like oil. One double bond is a monounsaturated fat, while several double bonds is a polyunsaturated fat.

When you hear words like “omega-3 fatty acid,” this simply means the double bond is on the third carbon (6th carbon for omega-6). Olives and olive oil, peanuts, canola oil (and other vegetable oils), avocado, nuts and seeds, and fish are high sources of monounsaturated and polyunsaturated fats.

FINALLY, a trans saturated fat occurs naturally in foods SOMETIMES, but most of our intake occurs when an unsaturated fat is partially hydrogenated to make it more stable in baked goods. Addition of a trans fat makes the unsaturated fat flat again, creating another dense, stackable chain.

In case you were wondering, fully hydrogenating a fat turns an unsaturated fat to a saturated one. You can find hydrogenated and partially hydrogenated (trans) fats in processed foods like margarine, vegetable shortening, fried foods, and baked goods like pastries, pies or cakes, among others!

How Does Fat Affect Your Body?

Once we eat foods with fat in them, the fat is broken down into smaller particles and absorbed through our small intestines. Once absorbed, fats and other lipids are essential to keep our bodies functioning. Not only do fats give us energy, lipids are necessary to build new cells and allow us to absorb the essential fat-soluble vitamins A, D, E, and K. Lipids are the essential building blocks that keep our nervous, immune, and reproductive systems running.

Not all fats are created equal, however. Once absorbed, fatty acids make their way to the liver and are then repackaged to be sent out into the blood stream. We know that saturated fats, and even more so trans fats, increase the production of low-density lipoproteins (LDL), aka “bad cholesterol”, in the blood stream.

Top image shows cholesterol in a human blood vessel. While the bottom image shows a normal blood vessel.

LDL increases deposition of cholesterol within the arteries AND creates inflammation along the inside walls of the vessels, creating narrowing. Over time, narrowing and hardening of the arterial walls can create high blood pressure and decreased blood flow to vital organs like the heart, kidneys, and brain. If an artery becomes completely blocked, one can experience a heart attack or stroke.

Unsaturated fats, on the other hand, do not have this relationship with LDL. Unsaturated fats, along with exercise, weight loss, and quitting smoking, can help raise high-density lipoproteins (HDL), aka “good cholesterol”, while lowering LDL. HDL picks up cholesterol from the blood and brings it back to the liver – they’re the street sweepers of our arteries, reducing plaque build-up. This is why we call HDL our “good” cholesterol.

Though saturated fats raise LDL (the bad guy), they can also raise HDL (the good guy), making their overall effect on health and cardiovascular disease somewhat controversial.

Trans fats, on the other hand, undoubtedly raise LDL while lowering HDL, increasing the risk for premature cardiovascular disease.

How Do We Apply This Information to Better Our Diets?

Trans Fats Are Always Bad

There is no jury out on this one, the results are in. Trans fats are always bad and increase risk for cardiovascular disease. Eliminating or significantly decreasing the amount of processed and packaged foods, as well as fried food, you eat will largely remove trans fats from your diet. Even if a food is fried in a “healthy” oil, the high heat can partially hydrogenate the oils creating trans fats. Avoid muffins, cakes, pastries, pop tarts, and any food label that contains partially hydrogenated oil in the ingredient list.

***For more ideas on this topic, please read my post: 12 Ways to Overcome Your Sugar Addiction.

Saturated Fats Are More Bad Than Good

Although saturated fats can raise both the bad and good cholesterol, several studies have shown that diets higher in saturated fats lead to more cardiovascular events. Data suggests that replacing saturated fats with unsaturated fats will improve your overall cardiovascular health. It is important to add that you must replace the saturated fats in your diet with unsaturated fats, or high fiber foods, in order to reap the benefits. Replacing saturated fats with high sugar foods may not improve your cardiovascular health at all.

Unsaturated Fats Are Good

Diets high in unsaturated fats have proven time and time again to decrease the risk of cardiovascular disease, hence the popularity of the Mediterranean diet. The Mediterranean diet is very high in monounsaturated fats found in olives, olive oil, and nuts, as well as high fiber foods (see below), such as whole grains, vegetables, and fruits. The diet is notoriously low in meat with sparing amounts of cheese and dairy. Unsaturated fats lower your “bad” cholesterol, and may help raise your “good” cholesterol.

High Fiber Foods Are Important

Fiber is the non-digestible roughage found in fruits, vegetables, nuts and seeds, legumes, and whole grains. It is only found in plant foods. Fiber binds cholesterol in the intestines, making it indigestible and non-absorbable, thereby removing it from your body and lowering your cholesterol and LDL. 

Super Foods Play a Role

While I don’t commonly recommend certain super foods based on the latest fad, there are some tried and true all-star foods out there, specifically when it comes to lowering LDL and decreasing risk for cardiovascular disease. Flaxseeds, psyllium husk, almonds, tomatoes, hazelnuts, walnuts, high-fiber whole grains (like bulger, barley, oats, quinoa, farro), beans and lentils, unprocessed soy foods (soy beans and tofu), avocados, turmeric, green tea, and unsaturated oils (like rapeseed, olive, canola) have all shown positive effects on cardiovascular health in studies.

Current Recommendations

The current guidelines recommend individuals get ~20-35% of their daily calories from fat, < 10% from saturated fat, and a little as possible from trans saturated fats. One gram of fat is equal to 9 calories, meaning if someone is eating a typical 2,000 calorie diet, they should be eating about 45-78 grams of fats per day.

Putting it All Together

Now that you have the building blocks of knowledge to make informed decisions about the types of fats you eat moving forward, let’s put it all together into a sample diet.

Breakfast: Oatmeal made with flaxseeds, berries, and unsweetened almond milk

Alternative: Whole wheat or sprouted whole grain bread toasted and topped with ½ of an avocado

Snack: Handful of mixed nuts, carrots with plant-based dip, and a cup of green tea

Alternative: Edamame and a piece of fruit, like an orange or apple

Lunch: Big salad with mixed greens, chickpeas, tomatoes, other veggies of choice, sunflower seeds or pepitas, quinoa, avocado, and oil-based salad dressing. Add lean meat or low-fat cheese sparingly, if desired.

Alternative: Veggie and three bean chili with corn chips and a side salad

Dinner:  Veggie stir-fry with tofu, peanut sauce, and whole grain noodles

Alternative: Fish tacos with tomato salsa, onions, cilantro, avocado, cabbage slaw (made with olive oil, lime and seasoning), homemade smashed (“refried”) beans, and whole grain tortillas with side of limes

Alternative #2: Brown Rice (or other whole grain like bulger or farro) bowl topped with cooked veggies (zucchini, broccoli, carrots, onion), garbanzos, tahini dressing (tahini, lemon juice, salt, pepper, cumin, pinch red pepper flakes), and seeds or pan roasted almonds

If you are struggling with your diet or are looking for support from a Registered Dietitian, send us a message through your Amaze app or call 720-577-5251. Our team is here to help.