Nutrition 101: Fats
Fats have been getting a lot of attention for a long time. Originally diets said low fat, no fat, all fats are bad fats. Then the fat message transitioned to only these fats, these fats are the healthy fats, eat them in small amounts. More recently, diets have found their way to the other end of the spectrum saying that fats need to make up a huge portion of the diet, especially replacing carbohydrates. Well which is it? Per usual, it’s a little bit of everything. It’s called balance. Here’s what I mean:
What are they?
Fats, or lipids but I prefer the term fats, are one of the three macronutrients in the diet, meaning that they are one of the three main ingredients in the diet along with carbohydrates and proteins. The chemical structure of a fat looks like 1 glycerol attached to 3 fatty acids. Chemistry. Fats can be divided into subcategories based on the length of their carbon chain & saturation aka the number of double bonds present in the carbon chain.
When dividing by chain length, or number of carbon molecules, we have short chain fatty acids (SCFA), medium chain fatty acids (MCFA), and long chain fatty acids (LCFA). SCFA and MCFA are easier for the body to absorb and are used more quickly than LCFA. LCFA must first be broken down into MCFA and SCFA. This is generally only discussed in detail if there is a fat malabsorption concern. More often, we’re focusing on the saturation of a fatty acid which is where we get the terms saturated fat, unsaturated fat, and trans fat.
Looking at the chemical structure of a fat, saturated fats contain 0 double bonds, monounsaturated fats contain 1 double bond, and polyunsaturated fats contain 2 or more double bonds. The double bond count is important when assessing things such as stability, susceptibility to oxidation via heat exposure (aka cooking methods), consistency, and ability for the fats to stack in the blood.
Unsaturated fats, mono- and poly-, can be easily identified as liquids at room temperature. Saturated fats are easily identified as solids at room temperature. Trans fats are made when unsaturated fats are made to be solid at room temperature through a process call hydrogenation. This rationale behind this process was to create a “healthy” unsaturated fat that could replace “unhealthy” solid fats in cooking - aka the birth of crisco and any oil that is labeled on the back of the package as “partially hydrogenated.” Research later found that the hydrogenation process creates a chemical structure that allows these trans fats to easily stack in the blood and contribute to things like clogged arteries and heart conditions. For this reason, trans fats have been banned and food suppliers are now required to remove them from products.
All fats, regardless of saturation, are broken down for energy use through a process called beta oxidation. In the cycle, fat is converted into acetyl-CoA that then goes to the TCA cycle, is converted to NADH/FADH2, travels to the electron transport chain then makes ATP - ENERGY. The main point of this is fats can be used for short term energy, but are not an efficient use of energy for the body, as the central nervous system, aka your brain & its constituents, runs on glucose. Whereas beta oxidation ultimately produces 1 ATP, one molecule of glucose (carbohydrate) produces 28 ATP - a much more efficient process. When the body is forced to use fats for energy, as in the body is not getting enough carbohydrate source, the body has to make energy very inefficiently and the fats are covered to ketones. Current diets love ketones and market the fat burning, weight loss, abilities of ketones; however, the production of ketones in the body is actually a sign that the body is under a lot of stress internally, is not able to run efficiently, and is inflamed. Not recommended.
Why do I need them?
Fats don’t just contribute to your risk for heart conditions. In reality, they actually play a big role in protecting your heart and your body. They are one of the 3 most important components of the diet after all. Dietary fats are important for the following:
Prevention of essential fatty acid deficiency
Absorption of fat soluble vitamins: vitamin A, vitamin D, vitamin E, vitamin K
Making vitamin D
Balanced blood lipids: HDL, LDL, VLDL, total cholesterol, and triglycerides
Temperature regulation
Protection of internal organs
Cellular structure
Hormone health and regulation
Brain health and cognition
Growth and development
Immune health
Blood pressure
Blood clotting
Satiety, palatability, flavor, texture of foods
What are the food sources?
A note: cholesterol is always linked with fats, as cholesterol is a fat. Something to know is that animal sources contain cholesterol; however, plant sources do not. I.E. nuts do not contain cholesterol because they are not an animal products.
Unsaturated Fats
avocado oil*
olive oil*
peanut oil*
canola oil
sunflower oil
corn oil
soybean oil
cottonseed oil
safflower oil
grapeseed oil
sesame oil
avocados*
nuts & seeds*
nut butters*
olives*
fatty fish (tuna, salmon, sardines, trout)*
hummus*
guacamole*
pesto*
mayonnaise
salad dressing*
tub margarine
Saturated Fats
coconut oil*
dairy: ice cream, cheese, sour cream, milk, butter*
palm (kernel) oil
animal fat*
bacon grease
Trans Fats
any indication of “partially hydrogenated” or “hydrogenated” oil on a label; historically:
prepackaged products
stick margarine
vegetable shortening
fried foods
Which fats should I eat?
When choosing an oil or fat, I recommend keeping it simple & choosing the most natural oils and fats- the things you can picture oil coming from or that are naturally very rich in oil like olives, nuts, avocado, coconut, & dairy and animal products. The starred options are the fat sources that I would most often recommend. I would not recommend many oils for regular use, including vegetable oil and canola oil, due to the need for significant processing such as high pressure and heat to extract the oil from the plant. This process can make the oils fairly unstable and susceptible to oxidation, which may cause inflammation in the body. You’ll often notice these some of these oils are more expensive (i.e. grapeseed, sunflower) which leads to spending unnecessarily and choosing a less beneficial oil for your health.
Many condiments are made using canola, sunflower, or palm oils. I recommend finding condiments made with olive oil or avocado oil when possible. This is not to say that you should never have a product made with canola oil or use sesame oil for flavoring - all foods have a place and can be part of a healthy diet. However, choosing naturally-occurring oils more often than not is a good rule of thumb.
How much do I need?
It’s recommended that fats make up 20-35% of an individual's daily diet with about 10% being saturated fats. So, saturated fats can be part of a healthy and balanced diet, but shouldn’t be the only or main source of fat. For most average, healthy adults, this can be simplified by aiming for around 5-7 teaspoons of oil per day. However, teaspoons of oil do not directly translate to other food sources in a 1:1 ratio, so it’s easier to think of it as 5-7 servings of fats per day. Specific recommendations vary based on age, gender, lifestyle, and health. Although falling somewhere in this goal range is desirable, it is just as important to pay attention to the quality of the sources. The highest diet quality is going to come from having variety in fat choices, as each food source will provide its own unique composition of nutrients.
What is a serving?
A serving of fat can generally equate to 1 tsp or about 2 thumb tips. This is a good guesstimate, but it depends on how much of the food is needed to provide the amount of fat that would equate to a serving. For example, where as fats are the main macronutrient found in oils & salad dressing, that’s not so for many solid food fat sources such as nuts, avocado, hummus, etc. Therefore, the solid foods usually need around 4 thumb tips to provide a serving of fat.
Resources
1. Department of Veterans Affairs. What Are the Types of Fats? Move.va.gov. https://www.move.va.gov/docs/NewHandouts/Nutrition/N09_WhatAreTheTypesOfFat.pdf. Nd. Accessed April 29, 2020.
2. Herman JR. Dietary Fat, Saturated Fat, Trans Fat, and Cholesterol. Pods.dasnr.okstate.edu. http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2388/T-3153web.pdf. Nd. Accessed April 27, 2020.
3. Liu AG, Ford NA, Hu FB, Zelman KM, Mozaffarian D, Kris-Etherton PM. A healthy approach to dietary fats: understanding the science and taking action to reduce consumer confusion. Nutr J. 2017;16(1):53. Published 2017 Aug 30. doi:10.1186/s12937-017-0271-4.
4. National Heart, Lung, and Blood Institute. Serving Sizes and Portions. nhlbi.nih.gov. https://www.nhlbi.nih.gov/health/educational/wecan/eat-right/distortion.htm. Nd. Updates September 30, 2013. Accessed May 30, 2020.
5. National Institute on Aging. Important Nutrients to Know: Proteins, Carbohydrates, and Fats. Nia.nih.gov. www.nia.nih.gov/health/important-nutrients-know-proteins-carbohydrates-and-fats. Nd. Reviewed April 29, 2019. Accessed April 28, 2020.
6. National Research Council (US) Committee on Diet and Health. Diet and Health: mplications for Reducing Chronic Disease Risk. Washington (DC): National Academies Press (US); 1989. 7, Fats and Other Lipids. Available from: https://www.ncbi.nlm.nih.gov/books/NBK218759/.
7. Position of the Academy of Nutrition and Dietetics: Dietary Fatty Acids for Healthy Adults
Vannice, Gretchen et al. Journal of the Academy of Nutrition and Dietetics, Volume 114, Issue 1, 136 - 153.
8. U.S. Department of Agriculture. What are “oils?” Choosemyplate.gov. https://www.choosemyplate.gov/eathealthy/oils. Nd. Accessed April 27. 2020.