Last week, I focused on carbohydrates, what they are and why we need them. This week I’m focusing on fats. More specifically, what they are, why we need them and what foods contains fats.
Fats, like carbohydrates, has been through the ringer. They were demonized for years for causing people to gain weight, for being unhealthy, and for increasing heart attacks. Yes, overconsumption of fat can cause people to gain weight, but so can over-consuming carbohydrates. Fats are not only healthy, but they are also an essential nutrient.
What are fats
Dietary fats are the most energy dense of the three macronutrients. Fats provides 9 kcal/gram, whereas, protein and carbohydrate provide 4 kcal/gram. Fats are also hydrophobic and are insoluble in our blood. They are unable to provide quick energy like carbohydrates and instead provide long-term energy.
Fats in its simplest form are fatty acids. Fatty acids are categorized by their length.
Short-chain fatty acids (less than 6 carbon atoms) are produced with dietary fiber is fermented in the colon and can cross the blood-brain barrier.
Medium-chain fatty acids (6-12 carbon atoms) can form medium-chain triglycerides. Medium-chain triglycerides are metabolized quickly and are used for patients that aren’t able to metabolize fats. MCT are commonly used in the clinical setting. Found in palm kernel oil and coconut oil.
Long-chain fatty acids (13-21 atoms) found in most animal and vegetable oils.
Very long chain fatty acids (22+ atoms) found in most animal and vegetable oils.
There are two types of fatty acids, saturated and unsaturated. Saturated fatty acids are mostly from animals. They are solid at room temperature, have a higher melting point than unsaturated fats, and are more stable than unsaturated fats.
Unsaturated fats are from plants and fish. The fats are liquid at room temperature and have a lower melting point. There are three types of unsaturated fats: monounsaturated, polyunsaturated, and trans unsaturated.
Monounsaturated fats are found in avocado, almonds, cashews, canola oil, olive, sesame seeds.
Polyunsaturated fats are found in walnuts, sunflower seeds, fish, and flax seeds/oil. Polyunsaturated fats include omega 3 and omega 6 fatty acids. These fatty acids are essential to our body. This means that our body cannot produce them and must obtain them from the diet.
Trans unsaturated fatty acids occur both naturally and artificially through food processing. We obtain natural trans fatty acids in small amount from ruminant animals. The trans fatty acids we eat from processing is extremely unhealthy to eat. These artificial fatty acids occur when an unsaturated fat (liquid) has been processed to become saturated (solid).
Food processors do this to make the product more stable and have a long shelf life. You will typically find trans fatty acids in foods such as baked goods, crackers, cookies, fast food, coffee creamer, and vegetable shortenings and margarines. Foods that contain trans fats have “partially hydrogenated” or “hydrogenated” on the good label in the ingredients section.
Food labels that claim to have no trans fat can actually contain up to 0.5 grams. This is why it’s important to read the ingredient list.
Why we need dietary fats
Fats are an important macronutrient, and like protein, are an essential nutrient. Fats are needed to form cell membranes, manufacture and balance hormones, brain and nervous system development, energy reserve, temperature regulation, and protection for our organs. Fat is also important for the digestion and transportation of fat-soluble vitamins that are required for growth, reproduction, and overall good health.
What foods contains fats
All animal and fish foods contain fats. Plant fats come from coconuts, palm, avocado, nuts, seeds, and oils. Keep in mind that most foods have a mix of all types of fats in them and are classified based on the fat that has a significant amount. For example, beef has mostly saturated fat, but also contains some monounsaturated and polyunsaturated fats.
How much fat should you eat
The amount of fat depends on your activity level and food preferences. Because they are essential and your body’s health depends on them, I typically recommend 25-30% of your total calories to come from fat. Women should especially eat at least 25% of total calories from fat. Anything lower than 20%, you run the risk of hormonal imbalances. This applies to men and women.
I also recommend eating approximately a third of saturated fats, monounsaturated, and polyunsaturated fats. Try to eat more foods that contain omega 3 fatty acids than foods that contain omega 6 fatty acids. A good rule of thumb is to eat a ratio of 4:1 (omega 6: omega 3). Even better is 1:1 (omega 6: omega3).
It’s best to limit consumption of artificially trans fats and vegetable oils that are high in omega 6 such as soybean or corn oil.