Good fats vs bad fats: not all fats are created equal. Some are absolutely essential to our health while others should be avoided at all costs. Learn to tell the difference + how to balance the fats in your diet (free printable guide included!)

Good Fats vs Bad Fats – Why it Matters and How to Tell the Difference

Good fats vs bad fats: not all fats are created equal. Some are absolutely essential to our health while others should be avoided at all costs. Learn to tell the difference + how to balance the fats in your diet (free printable guide included!)Believe it or not, fats are an absolutely essential part of a healthy diet. However, not all fats are created equal; knowing the difference between good fats vs bad fats is crucial to preventing disease and living a healthy lifestyle.

It’s also crucial to realize that eating clean (if you’re already following a clean-eating diet) doesn’t guarantee that you’re eating a well-balanced diet – it only means you’re eating a diet free of potentially harmful substances that are byproducts of general food production and processing. So read on to see if you’re including the right fats (clean or not) in your diet.

But first, lets bust a common myth.

Myth: Eating Fat Contributes to Weight Gain

I see this misconception everywhere, and it frustrates me beyond belief. Someone somewhere came up with the idea for the first fat-free food and came up with a genius marketing plan: make people think that avoiding eating fat will help them lose weight, then create fat-free versions of food that are ‘just as delicious’ as the ‘unhealthy’ full-fat versions. Then, to make sure these versions are ‘just as delicious,’ they often add large amounts of sugar and salt (and many artificial ingredients) to make up for the lack of fat (which actually adds a lot of flavor to food).

Even without all the added ingredients, fat free foods still aren’t a healthy choice. Why? Because our bodies need certain fats to be healthy. And if you somehow managed to eat a 100% fat free diet (which is generally considered impossible) you’d probably end up killing yourself. Fats are THAT important.

Why Do Our Bodies Need Fats?

As I discussed in an earlier post about protein, our bodies take the things we eat and break them apart into pieces that are then put back together into useful structures. And while our bodies are masters of recycling the pieces we give them, we need to make sure to give them those pieces in the first place through the foods we eat.

Fats are an important piece for our bodies because nearly every cell we have has a membrane made of fat (scientifically known as a lipid bilayer). Without this membrane, our cells would not be able to function (there would be nothing to keep the insides in and the outside stuff out). In addition, nerves in our body and neurons in our brain require a fatty casing to insulate them and allow electrical signals to travel effectively through our body (think of it like the plastic insulation on a wire).

Furthermore, there are four essential vitamins our bodies need that are fat-soluble, meaning they dissolve in fat (and don’t dissolve in water). These vitamins are A, D, E, and K. Since they are fat-soluble, if you don’t have fat in your body to dissolve them your body won’t be able to process them properly, meaning you won’t get any of the nutrient value from those vitamins.

Good Fats vs Bad Fats

While eating fat is an essential part of a healthy diet, it is equally as important to make sure to eat the right kind of fat, because some fats will contribute to your health while others will detract from it.

Good Fats

Of the three major categories of fats (unsaturated, saturated, and trans), unsaturated fats are considered the ‘good’ fats. These are fatty acid heroes of our bodies! These are the fats that provide our bodies with fuel as well as the essential fatty acid building blocks our bodies need to build a host of helpful fat molecules.

Unsaturated fats can be separated into two categories of their own: monounsaturated and polyunsaturated. Unsaturated simply means that there is at least one double bond within the fatty acid chain, and that the molecule carries less than it’s possible capacity of oxygen atoms (if it was at capacity it would be saturated with oxygen). Monounsaturated means there is only one double bond, and polyunsaturated means there is more than one.

So what makes this kind of fat good?

It turns out that there are two fatty acids that have been determined by science to be essential to human health. These are alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). [1] They are essential because they cannot be synthesized by our bodies. In fact, they happen to be the basis for synthesizing of the rest of the omega 3, 6, and 9 fatty acids in our bodies.

These two fatty acids are polyunsaturated fats, which means that including these fats in your diet is a must, because your body can’t get these essential fatty acids from any other source.

In addition, polyunsaturated fats are associated with a myriad of health benefits. They are shown to lower your risk for heart attacks [2], cardiovascular disease [3], and developing ALS [4][5]. They’ve also been associated with a reduced risk of breast cancer [6].

Foods that Contain High Levels of Polyunsaturated Fats

  • Fatty Fish (such as Salmon, Rainbow Trout, Tuna, or Sardines)
  • Walnuts
  • Certain Seeds (flax, sunflower, sesame, pumpkin, chia)
  • Certain Oils (corn, canola, and soybean)

There is actually a really nice info-graphic on Wikipedia to look at levels of fats in different foods. Scroll to the bottom and click [show] on the right to expand it.

Now what about monounsaturated fats? Well, they’re not essential to our bodies, but they still provide several health benefits. Most notably, monounsaturated fats are known for reducing ‘bad’ (low-density) cholesterol and promoting ‘good’ (high-density) cholesterol. (note: while this is widely considered true, it is still being debated among researchers) Substituting monounsaturated fats for saturated ones has also been shown to increase insulin sensitivity (which is a good thing). [7]

Foods that Contain High Levels of Monounsaturated Fats

  • Olive Oil
  • Nuts (almond, cashew, macadamia, peanut, pecan)
  • Egg Yolk
  • Avocados


Bad Fats

Saturated and Trans fats are widely considered to be ‘bad’ fats, meaning they do more harm than good for our health.

Saturated means that the entire molecule is saturated (full to capacity) with oxygen atoms, which requires that only single bonds be present, unlike an unsaturated fat which has at least one double bond.

While saturated fats are generally considered to be ‘bad’ fats (which is why I place them in this section), there is still no consensus as to their association with coronary heart disease (CHD). Several studies show that consumption of saturated fat correlates with a higher risk of CHD (or the inverse: low consumption is associated with lowered risk)[8][9][10], however several other studies show no conclusive correlation between CHD and saturated fat consumption.[11][12][13]

However, there has very conclusive research over the years that correlates saturated fats to high levels of low-density cholesterol (bad cholesterol). [14] And high levels of this cholesterol, as you have no doubt heard, are highly associated with risk of CVD (cardiovascular disease). [15][16]

Foods that Contain High Levels of Saturated Fats

  • Dairy Products
  • Most Meats
  • Variety of Candy, Cakes, and other Sweets
  • Butter and Lard
  • Coconut Oil and Palm Kernel Oil

You may be surprised to see coconut oil on this list, as it is lauded as one of the healthiest oils out there. And they’re not wrong. It has been found that the kind of saturated fat coconut oil contains make it a healthier and lower-risk substitute for different saturated fats such as butter. [17][18] Specifically, it is thought that the abundance of lauric acid in coconut oil, which is still a saturated fatty acid, allows it to have less of an effect on low-density cholesterol levels than other saturated fatty acids. So go forth, guilt-free my friends, and continue using coconut oil in place of butter!

Moving on to trans fats, the truly terrible fat. No debate.

Trans fat are fats that started out as unsaturated fats, and then underwent a slight molecular transformation during processing. Trans, when referring to a fat, literally means ‘across from.’ It originates from the fact that in this type of fat the hydrogen that are part of the double bond of an unsaturated fat are across from each other rather than next to each other. While this change seems inconsequential, it actually changes several properties of the fat. Most notably, it increases the melting temperature and reduces the tendency of the fat to become rancid (i.e. increases the shelf life); both of these properties are great for commercial producers of food, but not so great for our bodies.

While it is recommended that we keep our consumption of calories from saturated fats below 7%, the FDA recommends that trans fats be consumed in only trace amounts and actually labels them as “generally not recognized as safe.” As of June 16 2015, the FDA has mandated that all trans fats be removed from processed foods within the next three years. [19]They’re THAT bad.

Trans fats have been associated with increased risk of heart disease very consistently. [20][21][22] The mechanism behind this is still being explored, but it is currently thought that trans fats reduce the body’s ability to process the essential fatty acids, leading to an imbalance of phospholipids in the aorta. [23]

Trans fats have been associated with a myriad of other health issues such as Alzheimer’s disease [24], type 2 diabetes [25], obesity (this is the only fat associated with weight gain) [26], liver dysfunction [27], infertility in women [28], and depression [29].

Needless to say, this is a fat to avoid at all costs.

List of Foods that Contain Trans Fats

  • Anything with hydrogenated or partially hydrogenated oil (ex. Margarine, shortening)
  • Animal body fat and milk (tends to be trace amounts)
  • Human breast milk (likely a function of trans fat consumption of the mother)

At the end of the day, you only truly need to worry about consuming this fat in larger than trace amounts if you eat processed foods or eat out often.


So What Does All of This Mean For Day to Day Fat Intake?

That’s a good question. All this information doesn’t do you much good unless you can use it to formulate a plan to go forth and improve your life. So lets do that.

Step 1: Stop eating trans fats. This is a no-brainer, but it must be said.

Step 2: Keep saturated fats at less than 7% of your total calories. (as recommended by nearly every health organization in the world)

What does this look like though, in terms of a normal diet? Well, if we start with the general 2000 calorie diet (which is high for most women, by the way), 7% of 2000 is 140 calories. A nutrition label will separate out how many calories are from fat and specifies which kinds of fat are contained, so you can easily add them up. To put this in perspective though, this equates to about 2 servings of cheddar cheese, about 5 servings of 2% milk, about 2 tbsp of butter, about 4 nestle tollhouse cookies, or about 17oz of grass fed beef. (I’ve got a free personalized guide available to help with this at the end of the post!)

Step 3: Keep unsaturated fats at about 30% of daily caloric intake.

As above, lets do the math. 30% of 2000 is 600. That’s actually a pretty big chunk of your daily calories, but that’s ok, because remember, these fats are essential for your body. So in terms of common foods, thats 5 1oz servings of walnuts, 6 tbsp of olive oil, 3 entire avocados, or 3 filets of salmon. You can see from these that it takes a concentrated effort to ensure you consume enough unsaturated fats each day. (I’ve got a free personalized guide available to help with this at the end of the post!)

Step 4: Balance your omega 3 and omega 6.

It is actually quite important to consume a balanced amount of omega 3 and 6. Most experts believe that the closer you are to a 1:1 ratio between the two essential fatty acids, the healthier you are. [30] Most americans tend to consume a ratio closer to 20:1, which is vastly disproportionately high in omega 6. Some common ratios to help you balance your intake:

  • omega 6 : omega 3
  • hemp oil 2-3:1
  • olive oil 3-13:1
  • sunflower oil (all omega 6)
  • flax oil 1:3
  • corn oil 46:1
  • coconut oil (all omega 6)
  • avocado oil 13:1
  • Atlantic Mackerel 1:12
  • Atlantic Wild Salman 1:15
  • Tuna 1:24

As you can see, fish tend to be much higher in omega 3’s and nuts and seeds tend to be higher in omega 6’s. Eat moderately of both for a good balance. (I’ve got a free personalized guide available to help with this at the end of the post!)

Step 5: Let go of the idea that a ‘clean’ food is automatically a healthy food.

This is a very important distinction that many people fail to make. When you follow a clean eating diet, it can be very easy to choose the food you eat based solely on whether or not it is clean. However, nutritional profiles are just as important as how clean a food is. Just because you buy organic grass-fed butter doesn’t mean you can go through 4 sticks a week and still be healthy. And considering the ratios in step 4, even overloading on avocados and nuts without balancing with fish can be detrimental to your health, no matter how clean and raw/wild those foods are.

Wow, this turned into a pretty long post. Congrats on making it to the end, my friend! Now that you’re here, think about any questions you might have, and ask away in the comments below! I know things like this can be confusing, so I’m here to help. In fact, I even took the time to make and awesome FREE personalized guide for you guys to help you balance your fat intake. It helps you calculate how many calories of each type of fat you should eat everyday, and doubles as a handy printable list to remind you which foods have good fats. Click below to download it, plus get access to my ENTIRE library of FREE resources! (can I get a heck yes?!)


Good fats vs bad fats: not all fats are created equal. Some are absolutely essential to our health while others should be avoided at all costs. Learn to tell the difference + how to balance the fats in your diet (free printable guide included!)


[1] Whitney Ellie and Rolfes SR (2008). Understanding Nutrition (11th ed.). California: Thomson Wadsworth. p. 154.

[2] National Institute of Health (August 1, 2005). “Omega-3 fatty acids, fish oil, alpha-linolenic acid”. Archived from the original on 3 May 2006.

[3] Willett, Walter C (September 2007). “The role of dietary n-6 fatty acids in the prevention of cardiovascular disease”. Journal of Cardiovascular Medicine 8: S42–5.

[4] Veldink, J H; Kalmijn, S; Groeneveld, G-J; Wunderink, W; Koster, A; De Vries, J H M; Van Der Luyt, J; Wokke, J H J; Van Den Berg, L H (April 2007). “Intake of polyunsaturated fatty acids and vitamin E reduces the risk of developing amyotrophic lateral sclerosis”. Journal of Neurology, Neurosurgery, and Psychiatry 78 (4): 367–71.

[5]  Okamoto, Kazushi; Kihira, Tameko; Kondo, Tomoyoshi; Kobashi, Gen; Washio, Masakazu; Sasaki, Satoshi; Yokoyama, Tetsuji; Miyake, Yoshihiro; et al. (October 2007). “Nutritional status and risk of amyotrophic lateral sclerosis in Japan”. Amyotrophic Lateral Sclerosis 8 (5): 300–4.

[6] Patterson, R. E.; Flatt, S. W.; Newman, V. A.; Natarajan, L.; Rock, C. L.; Thomson, C. A.; Caan, B. J.; Parker, B. A.; Pierce, J. P. (2010). “Marine Fatty Acid Intake is Associated with Breast Cancer Prognosis”. The Journal of Nutrition 141(2): 201–206.

[7] Vessby B, Unsitupa M, Hermansen K, Riccardi G, Rivellese AA, Tapsell LC, Nälsén C, Berglund L, Louheranta A, Rasmussen BM, Calvert GD, Maffetone A, Pedersen E, Gustafsson IB, Storlien LH (2001). “Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: The KANWU Study”. Diabetologia 44 (3): 312–9.

[8]  Harcombe Z, Baker JS, Cooper SM, Davies B, Sculthorpe N, Di Nicolantonio J and Grace F. “Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis”. Open Heart 2: e000196.

[9] Siri-Tarino PW, Sun Q, Hu FB, Krauss RM (2010). “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease”. American Journal of Clinical Nutrition 91 (3): 535–546.

[10] Mente A, de Koning L, Shannon HS, Anand SS (April 2009). “A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease”. Arch. Intern. Med. 169 (7): 659–69.

[11] Schwab, U; Lauritzen, L; Tholstrup, T; Haldorssoni, T; Riserus, U; Uusitupa, M; Becker, W (2014). “Effect of the amount and type of dietary fat on cardiometabolic risk factors and risk of developing type 2 diabetes, cardiovascular diseases, and cancer: a systematic review.”. Food & Nutrition Research 58

[12] Hooper L, Summerbell CD, Thompson R, Sills D, Roberts FG, Moore H, Davey Smith G (July 2011). “Reduced or modified dietary fat for preventing cardiovascular disease”. The Cochrane Library (7): CD002137.

[13] Micha R, Mozaffarian D (October 2010). “Saturated Fat and Cardiometabolic Risk Factors, Coronary Heart Disease, Stroke, and Diabetes: a Fresh Look at the Evidence”. Lipids 45 (10): 893–905.

[14]  Clarke R, Frost C, Collins R, Appleby P, Peto R (1997). “Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies”. BMJ (Clinical research ed.) 314 (7074): 112–7. 

[15] Bucher HC, Griffith LE, Guyatt GH (February 1999). “Systematic review on the risk and benefit of different cholesterol-lowering interventions”. Arteriosclerosis Thrombosis and Vascular Biology 19 (2): 187–195.

[16] Lewington S, Whitlock G, Clarke R, Sherliker P, Emberson J, Halsey J, Qizilbash N, Peto R, Collins R (December 2007). “Blood cholesterol and vascular mortality by age, sex, and blood pressure: a meta-analysis of individual data from 61 prospective studies with 55,000 vascular deaths”. Lancet 370 (9602): 1829–39.

[17] Babu AS1, Veluswamy SK, Arena R, Guazzi M, Lavie CJ. “Virgin coconut oil and its potential cardioprotective effects.” Postgrad Med. 2014 Nov;126(7).

[18] Inayat A, Baig SA, Baqai T. “Does coconut oil reduce the risk of coronary artery diseases?” J Pak Med Assoc. 2013 Jun;63(6):797.

[19] “The FDA takes step to remove artificial trans fats in processed foods”

[20] “Mar 8 2014 FDA filing by HARVARD SCHOOL OF PUBLIC HEALTH – on the Tentative Determination Regarding Partially Hydrogenated Oils; Request for Comments and for Scientific Data and Information”.

[21] Food and nutrition board, institute of medicine of the national academies (2005). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). National Academies Press. p. 504.

[22] EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA) (2010). “Scientific opinion on dietary reference values for fats”. EFSA Journal 8 (3): 1461.

[23] Kummerow FA1, Zhou Q, Mahfouz MM, Smiricky MR, Grieshop CM, Schaeffer DJ (2004). “Trans fatty acids in hydrogenated fat inhibited the synthesis of the polyunsaturated fatty acids in the phospholipid of arterial cells.”. Life Sci. 74 (22): 2707–23.

[24] Morris MC, Evans DA, Bienias JL, Tangney CC, Bennett DA, Aggarwal N, Schneider J, Wilson RS (2003). “Dietary fats and the risk of incident Alzheimer disease”. Arch Neurol 60 (2): 194–200.

[25] Trans Fat Task Force (June 2006). “TRANSforming the Food Supply (Appendix 9iii)”. Retrieved 9 January 2007. (Consultation on the health implications of alternatives to trans fatty acids: Summary of Responses from Experts)

[26]  Kavanagh, K; Jones, KL; Sawyer, J; Kelley, K; Carr, JJ; Wagner, JD; Rudel, LL (15 July 2007). “Trans fat diet induces abdominal obesity and changes in insulin sensitivity in monkeys”. Obesity (Silver Spring). 15 (7): 1675–84.

[27] Mahfouz M (1981). “Effect of dietary trans fatty acids on the delta 5, delta 6 and delta 9 desaturases of rat liver microsomes in vivo”. Acta biologica et medica germanica 40 (12): 1699–1705.

[28] Chavarro Jorge E, Rich-Edwards Janet W, Rosner Bernard A and Willett Walter C (January 2007). “Dietary fatty acid intakes and the risk of ovulatory infertility”. American Journal of Clinical Nutrition 85 (1): 231–237.

[29] Roan, Shari (28 January 2011). “Trans fats and saturated fats could contribute to depression”. The Sydney Morning Herald

[30] Lands, WEM (2005). Fish, Omega 3 and human health. American Oil Chemists’ Society. ISBN 978-1-893997-81-3.

About Rachel

Rachel is a blogger and Biophysics Lab Manager who lives in Clemson, SC (go tigers!). After studying conventional pharmaceuticals and how they target specific ailments, she applied that knowledge to figuring out how essential oils can work to treat the same ailments, and ended up creating the blog The Essential Girl.

When she’s not blogging or sciencing the shit out of something in the lab, she likes to swing dance and teach group fitness classes.