I bet if you had a choice between full-cream and low-fat milk, you would choose the latter one, wouldn’t you?
Many people would make the same choice because they are certain about the dangers of fat for our health and fitness. However, there is no evidence that all fat is bad for you. As you will see, it depends on its type. Here’s how it works.
What is fat, exactly?
Fat is one of the main macronutrients (the other two are carbs and proteins) that are essential for our body. Fat molecules can have different names, such as lipids, triglycerides and fatty acids depending on their structure.
Triglyceride is a molecule that consists of glycerol and three fatty acids. Fatty acids are chain-shaped molecules with different types of bonds between their carbon atoms. Fatty acids with no double or triple bonds are called “saturated”, with one double bond are “monounsaturated”, with two and more – “polyunsaturated”.
Unsaturated fats like olive oil stay liquid at room temperature. Saturated fats like butter or coconut oil are solid at room temperature.
What does fat do in our body?
Depending on the types of their bonds, fat molecules are packed differently and they have different densities. That impacts how easily they can be transported and digested in our bodies. Studies show that some types of fats function better than others.
Polyunsaturated fatty acids also improve blood cholesterol levels. Some of them like the famous omega-3 and omega-6 fatty acids are essential for our health. Other fatty acids can be produced by our body itself, but we need to get these two with food.
These days, saturated fats are being rehabilitated from being absolutely bad (so it’s ok to leave that whipped cream in your basket). Eat too much, however, and they can raise the level of LDL 'bad' cholesterol. But when in balance, they are ok.
What’s wrong with trans fats?
There are also trans fats – unsaturated fatty acids with different structures. Trans fats are modified to become solid at room temperature like saturated ones. A small portion of trans fats come naturally from meat and dairy, but most of the them are artificially made for processed food to keep it looking good for a longer time.
This type of fat is the worst. It both raises your LDL "bad" cholesterol and lowers your HDL "good" cholesterol. Consumption of trans fats is linked to a higher risk of cardiovascular disease. The U.S. Food and Drug Administration (FDA) insists that trans fats are not safe.
Now, what should we eat?
No one is saying, “let's go to the supermarket to buy a ton of unsaturated fats”.
So let's talk about which food sources of fats to choose. First of all, there are no ‘clean’ fats in the real world of foods. Some products contain more saturated fats than unsaturated and vice versa, but all foods have a mix of fats.
The main sources of monounsaturated fats are vegetable oils (especially olive and canola), avocados, nuts and seeds. For polyunsaturated fats, look for fish such as salmon, tuna, trout, mackerel, sardines and herring and even oysters.
Saturated fats mostly come from meat and dairy products, but you can also find them in coconut and palm oils. If you have concerns about your heart health, you should take evidence-based recommendations and swap saturated fats for unsaturated (especially polyunsaturated) ones. This means, instead of a bloody ribeye for the next dinner, get a juicy salmon with Herbs de Provence and lemon.
Trans fats are not welcome on the table. Try to avoid margarine, fried foods, some baked goods (cakes, cookies, chips) and refrigerator dough. Rely on homemade foods rather than on processed food or fast-food dishes. Read the product labels.
1. There are two main types of fat, saturated and unsaturated.
2. Unsaturated fats stay liquid at room temperature; saturated ones stay solid.
3. There’s no need to give up on all the fats. Just substitute those potentially unhealthy fats for better ones.
4. And don't forget to avoid trans fats.
- Dietary fats: Know which types to choose. Mayo Clinic, February 2016.
- Final Determination Regarding Partially-Hydrogenated Oils (Removing Trans Fat). FDA, June 16, 2015.
- Is eating fat really bad for you? Here's what the science says. Jullia Belluz, Vox, April 2016.
- Saturated Fat: Good or Bad? Healthline, June 2017.
- Trans fat is double trouble for your heart health. Mayo Clinic, March 2017.
- Trans fats food fact sheet, British Dietetic Association.