I love fat. It’s filling, it’s nutritious, it makes for great skin, adds flavor to your food, and there is a whole class of vitamins (fat-soluble vitamins A, D, E, & K) that are found mostly in fat. Also, did you know that 2/3 of your brain is made of fat?? People tend to be scared of fat, because they equate it to making them fat. However, fats can be awesome for you if you eat the right types of fats in the right amounts.
Today, in this continuation of my Nutrition 101 series, I hope to teach you a bit about fats, what they do for your body, and what types of fats are best for your body.
What is fat?
Fats (aka fatty acids) are a group of compounds that are mostly insoluble in water. This means that if you added some of a fat into a glass of water and tried to mix it, the oil would stay separate from the water, instead of mixing into a solution. They can be solid or liquid at room temperature, although fats that are liquids at room temperature are usually referred to as oils.
Fats are classified according to their chemical shape and bonds. This is where you get the groups, such as saturated fats, monounsaturated fats, polyunsaturated fats, etc. Fats like omega-3′s and omega-6′s fit into those categories, but more on that later.
Fats tend to get a bad reputation because contains more calories (energy) per gram than either protein or carbohydrates. Fats contain 9 calories per gram, where carbs and protein only contain 4 calories per gram.
What happens to fat in my body?
As with carbohydrates, your body begins to break down fats as soon as they enter your mouth, using enzymes, called lingual lipases. These lipases break down the longer chains of fatty acids into shorter chains, called diglycerides.
Fat digestion takes a break in the stomach, and moves through to the small intestine without further digestion. When the diglycerides arrive in the small intestine, hormones are released, which trigger the release of pancreatic lipase from the pancreas, and bile from the liver/gallbladder. Lipase continues to break down the chains into fatty acids, while bile is used to emulsify the tiny fat particles, so they can be more easily suspended in the fluid content of the intestine.
After being broken down, fat is absorbed by the little fingers, called villi, which line the small intestine. From there, the little fatty acid particles are transported to the blood stream, and on to the adipose cells and muscle cells where they are either stored for later use or used as energy.
What are the differences between the different types of fats?
As I mentioned earlier, fats are grouped into categories based on their chemical structure, the way their carbon and hydrogen atoms fit together.
Saturated fats are called such because all of the hydrogens in the chain are “saturated” with hydrogens. They tend to be solid at a higher temperature than unsaturated fats. Pretty much all animal fats are saturated fats, as well as a few plant-based fats, such as coconut and palm oils. Saturated fats are generally thought of as being unhealthy, and have been linked to heart disease for many years. However, don’t let this scare you off of coconut oil! Coconut oil is unique, because it is more stable at higher temperatures than most oils, making it ideal to cook with. It also tends to increase HDL (good) cholesterol, and also is made up of shorter chains of fatty acids than most saturated fats, which have been shown to carry less risk.
Monounsaturated fats (MUFAs) are named for the single double bond that is contained in their fatty acids chains. One of the hydrogens is missing from the structure, causing a double bond to form between a pair of carbon atoms, and altering the structure of the fat. MUFAs are beneficial because they have a tendency to help lower LDL (bad) cholesterol levels. They are also said to help raise HDL (good) cholesterol levels, but this still being debated upon. Good sources of MUFAs are:
- Olives/olive oil
- Canola oil
- Macadamia nuts/oil
- Grapeseed oil
- Sesame oil
- Corn oil
- Sunflower oil
- Almond oil
Polyunsaturated fats (PUFAs) have multiple missing hydrogens/double bonds in their structure. Essential fatty acids, omega-3 and omega-6 fatty acids, are members of this family, named because their double bonds occur at the 3rd and 6th carbons, respectively. PUFAs have been shown to be beneficial for the cardiovascular system, and some even have positive effects on the brain. I would like to note that while salmon is high in omega-3 fatty acids, that they are also very high in saturated fat. Salmon contain omega-3′s because their diet is high in sea vegetables, which are an amazing source of omega-3′s.
Good sources include:
- Sunflower seeds
- Sesame seeds
- Peanuts/peanut oil
- Olive oil
- Flax seeds
- Hemp seeds
- Chia seeds
- Soybean oil
Trans fats are named for the specific structure of the double bond between two carbon atoms. Trans fats are very rare in nature, and are usually the result of a process called “hydrogenation” used in food processing. In foods like margarine, food scientists want to make liquid oils into a more solid form, so they bombard the double bonds with hydrogen atoms, hoping that some will move in. In many cases, not all of the bonds receive the hydrogens, but the bonds are still altered. If the hydrogens on either side of the double bonds end up on opposite sides, they are trans fats. It looks something like this: H/=/H, instead of H/=\H. It’s a pretty hard concept to grasp if you don’t have a solid chemistry background.
Trans fats are pretty much the worst fat out there for your body. Besides being unnatural, they also drive up your LDL cholesterol, and bring down your HDL cholesterol. The agencies that determine dietary recommendations have stated that trans fats are not beneficial for the human body in anyway, and should be avoided as much as possible. Many cities/states have approved motions to ban trans fats. Fast food, fried foods, and baked goods are most likely to contain trans fats. If you notice that an item that you pick up as any kind of hydrogenated oil in the ingredients, you’d be best to avoid it.
How much fat should I be eating?
Fats should make up about 20-35% of your daily calories. Remember, this is not 20-35% of your total food, just your calories. It equals out to about 44 – 78 grams of fat per day. Fats contain just over twice the calories of most foods, so keep that in mind. Your main sources of fat should be whole sources, such as nuts, seeds, and avocados. Oils can be used lightly in salads and cooking, but they should not be your main fat sources, as they are more heavily processed.
Fat is one area of nutrition where it is absolutely undisputed that plant foods rule over animal foods. Rarely can you find such strict rules of “animal foods will make you sicker” and “plant foods will make you healthier”, but in this case it is true. I hope you will now find it easier to make good choices about the fats that you put into your body.