Importance and function of fat in a healthy diet

Of the three macronutrients, or sources of energy for the body, fat is one that has been scrutinized for far too long. As with all macronutrients, they are essential for the body and must be obtained through the diet. Fat can be found in food in a few different forms; saturated, unsaturated, monounsaturated, polyunsaturated, and trans. While these fats are sometimes categorized as “good fat” or “bad fat,” this article will help you to better understand each type of fat and what purpose it serves in the body.

What function does fat have in the body?

Of the three macronutrients, fats provides the highest amount of calories per gram at 9kcal/g. Fat is necessary for absorption of fat soluble vitamins A, D, E and K. Fat is also necessary for building the membranes of cells that help the body function, as well as playing a role in blood clotting, muscle movement and inflammation. Some fats have more health promoting properties than others. It is important to be aware of what types of fats exist in different foods to make the most informed decisions regarding your diet and your health.

What are the different types of fat?

Now that we understand the important roles fat plays in the diet, it is important to understand that optimal health is based on type of fats. There are saturated fats, unsaturated fats including mono and polyunsaturated fats, and trans fats.

What are unsaturated fats?

Unsaturated fats can be broken down into monounsaturated fats (MUFA) and polyunsaturated fats (PUFA). These fats should make up the majority of fat in the diet and can have beneficial effects on health when replacing saturated and trans fats.

• Monounsaturated fats (MUFAs) are fats that are liquid at room temperature and include olive, canola, peanut, safflower and sesame oils. It is also found in avocado, and nuts and seeds. This type of fat can help to reduce harmful cholesterol in the blood and contributes vitamin E which has an antioxidant effect and helps us to reduce inflammation.
• Polyunsaturated fats (PUFAs) are fats that contribute vitamin E as well as omega 3 and omega 6 fatty acids which are important for many functions in the body including heart health, bone health and fighting inflammation. PUFAs can be found in soybean, corn, and sunflower oils as well as in walnuts, sunflower seeds, tofu and soybeans, oily fish such as salmon, sardines and fresh tuna.

What are saturated fats?

Saturated fats have been linked to increased levels of cholesterol as well as inflammation which can lead to heart disease, diabetes and other chronic diseases. The American Heart Association recommends limiting intake of saturated and trans fats to no more than 5% of daily caloric intake. On a typical 2000 calorie diet, this would be no more than 13g per day. Saturated fats are typically found in baked goods and fried food as well as fatty beef, lamb, pork, poultry with skin, lard, butter, cheese, and other dairy products made with whole or reduced fat milk. It is also present in palm oil, palm kernel oil and coconut oils, although these plant based oils do not contain cholesterol. 

What are trans fats?

Trans fats have been found to raise cholesterol levels and are directly linked to inflammation which can lead to heart disease and diabetes as well as other chronic diseases. Trans fats exist in both a natural and unnatural form. Natural trans fats exist in small quantities in meat and dairy products including beef, lamb and butterfat. Synthetic trans fats are made by taking vegetable oils and altering their structure through a process called hydrogenation. During this process, the oil is converted into a solid in order to prevent rancidity. Synthetic trans fats used to be present in many fried and baked goods as well as frozen pizza, cookies, crackers, and stick margarines and other spreads. A safe level of consumption has not been determined for synthetic trans fats. As a result, artificial trans fats have been banned in the United States as of 2015.

How does eating fat affect my cholesterol levels?

Fat is often linked to cholesterol levels, which is thought of negatively. In fact there are two types of cholesterol, HDL and LDL. HDL cholesterol is thought of as the health promoting type, while LDL cholesterol is harmful. Consuming both HDL and LDL cholesterol can be part of a healthy diet, but the goal is to consume a higher amount of HDL compared to LDL. A higher amount of HDL helps protect the heart, while a high amount of LDL contributes to plaque buildup on arteries which can clog arteries and lead to heart disease. The easiest way to regulate the type of cholesterol you are consuming is by paying attention to type of fats. MUFA and PUFA fats are considered healthy fats because they contribute to a favorable ratio of HDL to LDL. Saturated and trans fats on the other hand contribute to a damaging ratio of HDL to LDL. 

How do I know I am eating “healthy fats”

If you are ever uncertain what type of fat is in different foods, start by looking at the nutrition facts panel. Under the “total fat” section you will see a number and a percentage. If there are 14g of total fat, it will say 18% under the % daily value section, which tells us that one serving of the food contains 18% of recommended fat intake per day (based on a 2000 calorie diet.) Under this section will be a breakdown of what type of fat is in the item. The numbers will always add up to the number of total fat.  For example, a serving of peanuts contains 14g total fat, broken down into: 2g saturated fat, 0g trans fats, 4.5g polyunsaturated fat, and 7g monounsaturated fat. There is a daily value percentage next to total fat as well as saturated fat, because recommendations have been established on maximum intakes of saturated fats.

How to incorporate healthy fats into your diet

To incorporate healthy fats into your routine, start by making some healthy swaps. For example: 

• Switch from cooking with butter to a heart healthy unsaturated fat like olive oil.
• When choosing proteins, opt for fatty fish and chicken without skin over red meat which is higher in saturated and trans fats. 
• Cut down on intake of red meats and increase consumption of vegetarian sources of protein such as beans and legumes, nuts and seeds.
• Pay attention to nutrition labels and try to include foods with higher MUFA and PUFA levels and lower saturated fat and trans fat levels. 
• Upgrade your snacks! Focus on whole foods like nut butters and avocado rather than processed chips and cookies which may contain unhealthy fats.

Written by Marissa Gusmao
Edited by Alexander Franz
Reviewed by Morgan Murdock, RD.