The Skinny on Fats

October 10, 2013 Updated: October 10, 2013

Low fat, fat-free muffins, trans fat free margarine, extra lean ground beef; foods with less saturated fat, foods with heart healthy unsaturated fats or omega-3 fatty acids. Along any supermarket aisle, these ‘low fat’, ‘no fat’, ‘healthy fat’ products are easily spotted and comfortably nestled on the shelves. There are “good” fats to eat and “bad” fats to avoid. But what do all these different types of fats mean and how are certain kinds of fat harmful or beneficial to the body? Let’s sort out the good from the bad. 

1.What is dietary fat?
Dietary Fats are fats found in food. Fats come from both plant and animal sources. Dietary fat is one of the three macronutrients (carbohydrates, protein, fat). Macronutrients are nutrients that provide energy and calories to your body; it is the fuel the body needs for you to be able to function- walk, talk, think, etc. 

2. Why do we need fat in our diet?
Fat is essential to health and supports a number of the body’s functions. For example, unlike water-soluble vitamins, some vitamins such as A, D, E, and K dissolve only in fat and are then stored in the body. Fat also helps to produce hormones, store energy, maintain healthy skin, and protect organs. However, the type of and the amount of fat a person eats can influence their health. 

3. What makes a type of fat harmful or healthy?
Harmful dietary fat:
Saturated and trans fats are typically high in dietary cholesterol and raise LDL, “bad” cholesterol; trans fat can even decrease HDL, the “good” cholesterol. This increases the risk of heart disease. When too much blood cholesterol build up in the along the walls of the arteries leading to the brain or heart, it can cause arteries to narrow like a bottle neck; if the unhealthy cholesterol continues to build, this can clog up the artery and inhibit blood and oxygen delivery to the brain or heart causing chest pain and even a heart attack. 

Saturated fats mainly come from animal sources such as meat and dairy products; they are usually solid at room temperature.

Saturated Fats
Animal sources: 
• High fat dairy products: cheese, cream, butter, whole milk, regular ice cream
• Skin and fat of poultry, fatty meats: • lard
Plant sources:
• palm oil, coconut oil

Trans fats
Foods high in partially hydrogenated vegetable oils:
• hard margarines
• shortenings
• commercially fried foods
• some bakery goods: cookies, pies, donuts


4. Healthier dietary fat:
Unsaturated fats such as monounsaturated and polyunsaturated fats help to lower cholesterol when eaten in place of saturated and trans fats. Monounsaturated and polyunsaturated fats help reduce “bad” cholesterol and provide nutrients to help develop and maintain the body’s cells. Monounsaturated fats are typically high in Vitamin E, an antioxidant; polyunsaturated fats play a crucial role in brain function and normal growth development. Omega-3 is a type of polyunsaturated fat that helps protect against heart disease.

Unsaturated fats occur in vegetable oils, nuts, fatty fish; oils are usually liquid at room temperature. 

5. Diets high in fat can increase the risk for obesity, heart disease, and diabetes. Any type of fat is high in calories. Because fats provide double the calories per gram – 9 calories per gram versus 4 calories per gram from carbohydrates and protein – it is important to be aware of the amount and types of fats we eat. Too much of any macronutrient (carbohydrate, protein, fat) can lead to weight gain. To avoid additional calories, substitute saturated fats and trans fats with poly- and unsaturated fats rather than adding these fats to your diet.

Monounsaturated fats
Vegetable oils:
•olive, canola, peanut, sunflower, sesame
Other sources:
• avocado, peanut butter, nuts, seeds

Polyunsaturated fats
Vegetable oils:
• soybean, corn, cottenseed
• Cold-water fish: salmon, tuna, mackerel, anchovies
• flax

Tips for including appropriate amounts of healthy, unsaturated fats into your diet:

• Eat most of your calories from plant foods such as grains, fruits, vegetables
• Replace solid fats (meats/dairy fats and shortening) in cooking with liquid vegetable oils
• Trim fat and skin from meats
• Limit intake of high-fat processed meats (bacon, sausage, salami, other cold cuts)
• Choose low fat or fat free dairy products. This decreases the saturated fat, but contains the same nutrients.
• Replace chips or candy with a serving of dry roasted nuts as a snack
• Choose fruits as dessert more often
• Use the Nutrition Facts Label to help choose foods lower in fat, saturated fat, cholesterol

United States Department of Agriculture. (2000). Choose a diet that is low in saturated fat and cholesterol and moderate in total fat. Retrieved from 

Caroline Leung is a registered dietitian in the New York City area. She has an interest in nutrition for the prenatal and diabetic population. In her free time, she writes about all things nutrition at her website:


The views and opinions expressed in this article are those of the author and do not necessarily reflect the position of The Epoch Times.