Fats: the good, the bad and the worst

Fats come in different gradients: good, bad and worst. Also, how they break down inside your body affects your overall fatty acid balance. Here’s a quick lowdown on the different type of fats and how they affect your long-term health.

All fats have a similar chemical structure: a chain of carbon atoms bonded to hydrogen atoms. But, based on scientific findings on how they affect our health, we know there are different kinds of fats ⁠— the “good” fats like monounsaturated fats and polyunsaturated fatty acids (omega-3 and omega-6), the “bad” fats such as saturated fats and the “worst” are the trans fats.

What makes them different from each other is the length and shape of the carbon chain and the number of hydrogen atoms connected to the carbon atoms. Even the slight variation their form thus translates into crucial differences in their function and how they affect your health.

Also, fats in our food sometimes don’t stay static but are transformed into other types of fats. For instance, SFAs break down into monounsaturated fats (MUFAs) inside our body. And therefore, although MUFAs are good fats and should be part of your diet, an excess MUFA% is an indication of an SFA-rich diet which is bad for your health.

It is because of such nitty-gritty it is important to understand not only the types of fats but also how they react inside your system to be able to maintain a healthy fatty acid balance.

Total fat intake: between 25% to 40%

Before we dive into the “good” and “bad” fats, let's quickly brush up on the fundamental concept of daily energy intake (or calorie intake). Whatever you each every day add to your total energy intake. Unless you are looking to increase or decrease your body weight, your daily energy intake should remain fixed. However, for good health, it is also important to have a balanced energy intake, or a balanced diet, where each component, including carbohydrates, proteins, fats, should be part of your daily meals. Thus, each nutrient has a daily recommended intake limit. For instance, if your total daily energy intake carbohydrates shouldn’t be more than 60% and proteins should be between 10% to 20%.

For a healthy adult, the recommended fat intake is between 25 to 40% of the total energy intake. Meaning, even good fats shouldn’t exceed that limit. The key to having a good fatty acid balance to therefore increase your good fats (if you are below the recommended level) at the same time replace your “bad” fats intake with “good” fats.

Recommended daily fats intake

The good fats: PUFAs and MUFAs

Good fats come mainly from vegetables, plant-based oils, nuts, seeds and fish.

Polyunsaturated fats (PUFAs), like omega-3 and omega-6, are essential for your body. They are a source of energy, needed to build cell membranes, help you absorb important vitamins and minerals, essential for blood clotting, muscle movement and reduce inflammation. Unfortunately, our bodies can’t produce these good fats. So, we need to make sure to include them in our everyday diet.

Nutritionally, like PUFAs, MUFAs (monounsaturated fatty acids) are also considered good fats. They are, for instance, found in peanut oil, canola oil, avocados, and most nuts, as well as high-oleic safflower and sunflower oils. While they are good as part of your diet, excessive levels of MUFA in your blood is considered bad. That’s because, as mentioned earlier, SFA (the bad fats) also break down into MUFAs inside the body and therefore a high MUFA level in the blood is actually a sign of unhealthy diet. A high MUFA level is therefore often an indication of unhealthy body weight and insulin resistance (a condition in which your cells have trouble utilising excess glucose from your bloodstream). Over time, this may develop into diabetes. It’s, therefore, better to maintain a lower MUFA%. Read more about why having a high MUFA% in your blood is bad for long-term health here.

The bad fats: SFAs

SFAs a.k.a. saturated fatty acids are found in foods like butter, cheese, red meat, coconut oil, whole milk, other whole-milk dairy foods and most commercially prepared baked foods.

So, why are they categorised as “bad”? Research says, a diet rich in saturated fats can increase the level of harmful LDL-cholesterol in your blood, which prompts blockages to form in arteries in the heart and increase your heart disease risk. Therefore, most nutrition recommendations ask you to limit saturated fat to under 10% of daily calories.

However, a few recent studies have found that the association between a few types of SFAs and heart diseases may not be that straightforward.

The main conclusion is that replacing SFAs with polyunsaturated fats like vegetable oils or high-fibre carbohydrates is the best bet for reducing the risk of heart disease. On the other hand, replacing saturated fat with highly processed carbohydrates could do the opposite. Therefore, you should also be keeping an eye on your SFA intake.

The worst fats: trans fats

Trans fats found in food items like cookies, pastries and fast food. Research says, eating foods rich in trans fats increases the amount of harmful LDL-cholesterol in the bloodstream and reduces the amount of “good” HDL-cholesterol. Trans fats also increase inflammation level, which is linked to heart disease, stroke, diabetes, and other chronic conditions. Studies also show they contribute to inflammation, which increases the risk of developing type 2 diabetes, heart illnesses, stroke and other chronic diseases. Trans fats are harmful even when consumed in very small amounts. Research shows, for every 2% of calories from trans-fat consumed daily, the risk of heart disease rises by 23%. In short, trans fats are the worst type of fats, and you should be staying away from them.

Fatty acids are not the only factor affecting your long-term health. My Nightingale blood analysis provides a comprehensive picture of your health with over 20 different health results from a single blood sample. It includes a health index that gives an overview of your health, 6 health indicator ⁠— heart age, diabetes resistance, fatty acid balance, inflammation, cholesterol balance and blood sugar ⁠— that provide one-score summaries of different aspects of your wellbeing and numerous other biomarkers (such as GlycA, omegas, glucose and BCAAs) that give an in-depth insight into your metabolic health.