fats : which to enjoy and which to avoid

One of the great things about the ketogenic lifestyle is enjoying dietary fats. Not only are fats delicious, adding wonderful flavors to our diet, they are satiating and supply our bodies with energy (1). They can also help us lose weight and potentially provide many health benefits.

Some dietary fats are better for us than others. Which fats are good and which are bad depends on your perspective.

The Best

In the ketogenic paradigm, saturated fats are considered the best. Saturated fats are stable fats that are typically solid at room temperature. Most saturated fats come from animals—meat and dairy. High quantities of saturated fats are found in foods such as beef, lamb, pork, poultry with skin, butter, cream, ghee, lard, bacon fat, duck fat, beef tallow, buffalo tallow, and mutton tallow. The higher the amount of SFA (Saturated Fatty Acid) the better.

A special category of saturated fats is considered to be the best of the best: MCT’s (Medium Chain Triglycerides) (2). These are found in high concentrations in coconut oil and palm kernel oil. The body is able to more rapidly and efficiently absorb and metabolize medium chained triglycerides, making them superior to their longer-chained counterparts. MCT’s are not stored in fat cells but are instead converted into ketones providing fuel for the body (3).

In the past, saturated fats were given a bad rap and considered unhealthy. It is now believed that saturated fats may actually contribute to brain, bone, and heart health (4). A 2010 review of the scientific literature (Siri-Tarino, et. al.) published in The American Journal of Clinical Nutrition calls in to question long-held beliefs associating consumption of saturated fats with increased risks of strokes, cardiovascular disease or coronary heart disease.


Fats in the “good” category include monounsaturated fats, natural trans fats, and natural polyunsaturated fats.

Monounsaturated fats are well-known for being healthy. They are credited with providing protection from heart disease, reducing insulin resistance, and strengthen bones. Monounsaturated fats are found in high percentages in olives, avocados, almonds, extra-virgin olive oil, and avocado oil (5).

Natural trans fats are found in beef and dairy. Unlike man-made hydrogenated trans fats, natural trans fats have healthy benefits that can include reduce risk factors associated with heart disease, diabetes, and obesity, so there is no need to fear them (6).

Natural polyunsaturated fats, specifically those containing high quantities of omega-3, are desirable, as well. High concentrations of polyunsaturated fats are found in chia seeds, flax seeds, and fatty fish such as salmon, mackerel, sardines, herring, and albacore tuna.

But polyunsaturated fats can cross the line into the “not-so-good” category. Polyunsaturated oils are prone to oxidation and, therefore, have a short shelf-life and should not be heated (7). Instead, they should be used sparingly to finish dishes or in dressings. Examples of polyunsaturated oils include grapeseed oil, sunflower oil, and flaxseed oil.


“Bad” fats are the ones that have been industrially modified or over processed.

Because of the extreme refining and production process of many commercially produced polyunsaturated oils—such as canola oil, corn oil, soybean oil, and safflower oil—these oils are undesirable and should be avoided.

Artificial trans fats are the worst of the worst (8). For decades, partially hydrogenated oils—the main source of these trans fats—was found in abundance in crackers, margarine, biscuits, cakes, donuts, and the like. Due to overwhelming evidence of the detrimental effects of these synthetic trans fats, the FDA mandated that food manufacturers remove them completely from all products by June 2018.

In summary

Yes, there are “good” fats and “bad” fats. Obviously, we should avoid the “bad” fats—those icky synthetic and over processed ones. Of the “good” fats, though, some are better than others: MCT’s are the best, followed by all other saturated fats, then monounsaturated fats, and finally polyunsaturated fats (particularly those rich in omega-3).

As a general rule, fats are like the other foods in our diet: the ones with the least amount of processing are typically the best; organic is better than non-organic; in the case of fats from animals, grass-fed is preferred; and, when choosing oils, look for ones that are cold- and/or expeller-pressed.

“Good” fats contribute to good health. By following a ketogenic diet, we have the opportunity to partake of all these yummy, delicious “good” fats in great abundance. Enjoy.

Note: It is important to remember that changes in diet can be hazardous for some individuals, so make sure to check with your healthcare provider before trying any new plan of eating. I am neither a physician nor a dietician, so nothing in this article should be interpreted as medical or nutritional advice.


(1) Rania Abou Samra. Fats and Satiety. Fat Detection: Taste, Texture, and Post Ingestive Effects. Chapter 15. Montmayeur JP, le Coutre J, editors.Boca Raton (FL): CRC Press/Taylor & Francis; 2010.

(2) Marie-Pierre St-Onge Peter J. H. Jones. Physiological Effects of Medium-Chain Triglycerides: Potential Agents in the Prevention of Obesity. The Journal of Nutrition, Volume 132, Issue 3, 1 March 2002, Pages 329–332,https://doi.org/10.1093/jn/132.3.329. 01 March 2002.

(3) Camille Vandenberghe Valérie St-Pierre Tyler Pierotti, et. al. Tricaprylin Alone Increases Plasma Ketone Response More Than Coconut Oil or Other Medium-Chain Triglycerides: An Acute Crossover Study in Healthy Adults. Current Developments in Nutrition, Volume 1, Issue 4, 1 April 2017, e000257,https://doi.org/10.3945/cdn.116.000257. March 22, 2017.

(4) Aseem Malhotra, Rita F Redberg, Pascal Meier. Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions. British Journal of Sports Medicine Volume 51, Issue 15. April 25th, 2017.

(5) American Heart Association (AHA). Monounsaturated Fat. heart.org. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/monounsaturated-fats#.W5CrI-hKg2w. June 1st, 2015. Accessed Sep. 18th, 2018.

(6) Harvard Medical School. “Natural” trans fat less harmful than artificial version. health.harvard.edu. https://www.health.harvard.edu/press_releases/natural-trans-fat-less-harmful-than-artificial-version. Published: July, 2008. Accessed Sep. 18th, 2018.

(7) Ling Tao. Oxidation of Polyunsaturated Fatty Acids and its Impact on Food Quality and Human Health. ADVANCES IN FOOD TECHNOLOGY AND NUTRITIONAL SCIENCES Open Journal http://dx.doi.org/10.17140/AFTNSOJ-1-123 Adv Food Technol Nutr Sci Open J ISSN 2377-8350

(8) Mohammad Perwaiz Iqbal. Trans fatty acids – A risk factor for cardiovascular disease. Pak J Med Sci. 2014 Jan-Feb; 30(1): 194–197.