Understanding Fat

Episode #4 of the course How to live a healthy lifestyle by FutureLearn

Fat has been demonized over the past few decades for causing creeping waistlines and an increase in the number of people suffering from chronic diseases such as diabetes and heart disease. However, there’s more to fat than meets the eye; without it, our bodies couldn’t function. Fat (as well as carbohydrates and protein) is a macronutrient needed to maintain a healthy body and provide us with energy.

The fat we all know about is the subcutaneous fat under our skin that gives us wobbly bits. But in fact, fat is broken down and utilized throughout the body and is essential to the structure of cell walls, the production of certain hormones, and the absorption of the vitamins A, D, E, and K—functions essential to human life. The misconceptions about fat come from its different types, sometimes labelled “good fats” and “bad fats.”

Bad fats
Fats are classified as either saturated, monounsaturated, or polyunsaturated, depending on the chemical structure of the fatty acids they contain. Saturated is the “bad” fat—the fat in cakes, pastries, and biscuits that is harmful to health. In the 1980s, trans-fats also appeared—a new type of fat to produce margarines. This type of fat is often said to be the worst of the bunch, since it increases cholesterol levels, which can lead to heart disease.

Good fats
Unsaturated “good fats” not only provide us with the essential fatty acids that our bodies can’t produce on their own, they also help lower cholesterol levels. The good fats are monounsaturated and polyunsaturated. These fats are commonly liquid at room temperature and often come from plants. Monounsaturated fats come in the form of avocadoes, olive oil, and nuts, while polyunsaturated fats come from fish, leafy greens, and seeds. Most of us don’t eat enough of the good fats.

Fat storage
Just 1g of fat provides nine calories, compared to four calories per gram for protein and four calories per gram of carbohydrates, so fat is a valuable form of energy in the body. However, problems occur when we eat more energy than our bodies require; this excess energy is stored as fat. The amount of energy we need each day is called our Total Daily Energy Expenditure (TDEE), which is a sum of our basal metabolic rate (the energy our body uses to do its primary functions), the thermic effect of digestive processes in our bodies, and the energy expenditure of any physical activity we have done that day. If we consume more calories in a day than our TDEE, we will store the excess energy away as fat. However, where we store this fat holds the key for why some people suffer the ill effects of weight gain and obesity more than others. Those who lay fat around their abdomen are said to be at a higher risk of developing diseases such as heart disease and diabetes, since this fat places undue stress around their vital organs and is more metabolically active.

Recommended free course

Obesity: Causes and Consequences

Recommended book

“Salt Sugar Fat: How the Food Giants Hooked Us” by Michael Moss

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