Fats… poor demonized and misunderstood fats. Almost like the middle child of the macronutrient trio. Aside from Carbohydrates which are quite often condemned, no other nutrient is as unappreciated as fats. Hopefully, in this 4-part series, we’ll be able to unravel some of the misconceptions associated with fats and oils, and by the end be able to make more educated decisions on our fat intake.
Fats, also known as oils or lipids are important for supporting cell growth and maintenance, providing the body with warmth and protecting your organs. Interestingly, 1 gram of this nutrient can provide 9 kcal (calories) of energy, in comparison to Carbohydrates and Protein which provide about 4kcal per gram. Meaning that fats are “energy-dense” (you might want to remember that phrase).
When we speak about dietary fats, we are referring to a molecule consisting of a glycerol backbone and 3 fatty acid chains. These are called triglycerides by scientists and health professionals. Excess fatty acids which have not been used for energy production or other bodily functions are stored as… you guessed it, Fat in tissues around the body called adipose.
So why is this structure even important?
Each of the fatty acid chains, represented by R in the diagram, can vary in length (number of carbon atoms), the amount of hydrogen (H) bonded to them, called saturation and how the hydrogens are positioned (trans vs cis configurations). The more hydrogen atoms held closely by the fatty acid chains, the easier it is to pack closely together. Of the types of fats we’ll talk about, saturated fats hold the most hydrogen atoms close to the carbons and are solid at room temperature.
Whereas having fewer hydrogens (unsaturation) leads to kinks in the fat chains, like curly hair so it doesn’t lay flat in a standard shape. Hence unsaturated fats (oils) are liquid at room temperature. If only my Chemistry lecturers could see this now… 🤓
Because fat can consist of multiple types of fatty acids and triglycerides, we usually name them based on the majority present. Typically, saturated fats are found mostly from animal sources, while unsaturated fats are in higher concentrations in plants, but of course, they are exceptions.
But why are fats been considered the devil?
Keep in mind there are two major kinds of dietary fats, saturated and unsaturated, all others are just subcategories.
Numerous research papers and scientific reports suggest links between saturated fat intake, high blood cholesterol levels and the incidence of heart disease. Evidence has shown that high saturated fat intake has been associated with increased low-density lipoprotein cholesterol (LDL-C) levels, considered the “bad” cholesterol and increased total blood cholesterol. These may play a role in the buildup of plaque in blood vessels (atherosclerosis) and result in coronary heart disease (CHD) and stroke. Although this is not the only pathway to developing CHD, research continues to suggest taking caution surrounding saturated fat consumption to avoid the risk of CHD.
In fact, in 2018 the UK Scientific Advisory Committee on Nutrition (SACN) confirmed that saturated fat intakes should not change from the commendations made in 1991 and 1994, due to the associated risks. They concluded that saturated fats should be replaced with unsaturated fats, and where it was unavoidable, saturated fat intakes should be kept low. Up to 10% of energy intake can come from saturated fats which are roughly 22g on a basic 2000 calorie diet.
Over time, this advice has been oversimplified to “reduce your fat intake”… “fats give you heart disease”… “don’t eat fat”. While this is not necessarily untrue it is an overestimation of the health advice and can result in the omission of other healthier fats which play important roles in body function.
Weight gain and low-fat diets
As previously mentioned, consuming too much dietary fat can cause the body to store it in tissues. This is especially dangerous if more is being stored around the organs such as the heart and liver. Excess weight (obesity) can affect the optimum function of organs and can lead to disease such as hypertension and type 2 diabetes mellitus, as well as stroke and heart attack.
You’ve probably seen lots of low-fat diets and foods. These were especially popular in the 1980s. And while it is great advice to reduce total fat intake, we must be mindful to reduce without replacing with other macronutrients. Particularly refined carbs and sugar because these will still count to our calories and can cause weight gain too.
Remember, any excess calories the body has can be stored as fat. Eating a balanced diet and staying active is a better way of ensuring calories are used up and preventing heart disease.
There are lots of ways to reduce total fat intake without cutting out fats completely or losing diet diversity, which we’ll discuss later in this series.
Just keep in mind, fats are important for repair, immunity, growth and vitamin absorption so some is still better than none at all. In our usual diet, we should aim for no higher than 35% of energy from total fat (that includes the unsaturated, saturated and trans fats) which is roughly 78g of fat in the average 2000 kcal diet.
Have you ever been on a low-fat diet or bought lower-fat options to reduce your weight? Have you ever discussed low-fat diets with your doctor or a nutrition professional? What are your experiences with fats and oils?