Bad Fats, Good Fats: What Do We Know?

Good and Bad Fats

Eating a healthy diet is more important than ever. But how do you know you’re making the right food choices?

For several years people were advised to avoid fats to control their weight and blood cholesterol. People opted for low-fat foods. However, they didn’t get any healthier, probably because they cut down on all fats, including good and bad fats.

It is well known that a diet high in fat, especially saturated fats, can increase the cholesterol level in your blood, thereby increasing your risk of heart disease. But does it suffice to banish fat completely from your diet? Of course not. Now the challenge that most people face is that they don’t know the type of fat that’s good for the body.

What Are Bad Fats and Where Can You Find Them?

Some fats have been shown to increase our risk of heart disease. These are trans and saturated fats.

Trans Fat

Trans fats are known to be the most dangerous type of fat. These fats can cause an increase in your blood cholesterol levels. It is therefore recommended that trans fats should not make up > 2% of the energy derived from our diet. The good news is, trans fats are gradually disappearing from the market, so many people no longer consume large amounts of this fat.

Where Can You Find Trans Fats?

You can find trans fats in meat, dairy products, and hydrogenated vegetable oil. You should always check whether a brand contains hydrogenated oil before purchasing it.

Saturated Fat

This is the most common type of fat that is sold in supermarkets. It’s also what we typically eat. Like other fats, saturated fats are converted in the liver to cholesterol, which is transported in the blood as high-density lipoprotein (HDL) and low-density lipoprotein. At high levels, LDL can cause the deposition of fats in the arteries and in the long-run, these become clogged, increasing your risk of heart disease and stroke. Conversely, HDL cholesterol picks up excess cholesterol in the body and transports it to the liver, where it is discarded.

Where Can You Find Saturated Fats?

Many foods contain saturated fats. In most cases, saturated fats come from animals (meat and dairy products), ghee, butter, lard, cheese, sausages, creams, cakes, and pastries, as well as coconut oil (learn more about the benefits of coconut oil here). Other sources include plants (palm oil). In general, we should not get > 11% of our energy (KJ/kcal) from saturated fats. An average man should consume no more than 30g of saturated fat per day. A woman should have no more than 20g per day, while children should have less.

What Are Good Fats and Where Can You Find Them?

These generally refer to unsaturated fats. Evidence demonstrates that cholesterol levels can be lowered by replacing saturated fats with unsaturated fats. Unsaturated fats can be either polyunsaturated or monounsaturated. Monounsaturated fats help decrease the levels of LDL cholesterol and maintain HDL cholesterol. Polyunsaturated fats—also known as essential fats because although we need them for normal body functions, our bodies cannot produce them— decrease LDL cholesterol levels when eaten in place of saturated fats or diets rich in highly refined carbohydrates. These fats have also been demonstrated to decrease triglyceride levels. Polysaccharides are further divided into omega-3 and omega-6.

Where can you find unsaturated fats?

These fats are primarily obtained from vegetables, seeds, nuts, and fish.

Monounsaturated fats can be obtained from the following:

  • Olive oil
  • Canola oil
  • Peanut oil
  • Sunflower oil
  • Avocados
  • Most nuts

Omega-3 can be obtained from the following:

  • Oily fishes, including salmon, mackerel, sardines, herring, kippers, tuna, and trout.

Omega-6 can be obtained from the following:

  • Safflower
  • Sunflower oil
  • Corn oil
  • Some nuts

Previous research demonstrated that a lower ratio of omega-6/omega-3 fatty acids was more desirable in decreasing the risk of chronic diseases such as cardiovascular disease, cancer, as well as inflammatory and autoimmune disease. The bottom line is to eat more omega-3 by including at least two portions of fish every week in your diet (containing one of oily fish).


  1. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002 Oct;56(8):365-79.
  2. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010; 91: 535–546.
  3. Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med 2010; 7: e1000252.
  4. Yamagishi K, Nettleton JA, Folsom AR. Plasma fatty acid composition and incident heart failure in middle-aged adults: The Atherosclerosis Risk in Communities (ARIC) Study. Am Heart J 2008; 156: 965–974.


Princila earned a Doctor of Medicine degree in 2006 and worked as a general practitioner for nearly two years before moving to Saudi Arabia. Her passion for writing took its toll, and she ended up switching careers to work in the medical publishing industry. She also has a passion for healthy food, which prompted her to take several online courses in nutrition and health offered by Wageningen University. Are you into research? You can connect with Princila on ResearchGate or LinkedIn. Visit our About page for details.

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