Fuel for Thought
Weekly Column By Barb Bryan, BSc(Pharmacy), BSc(Nutrition) APA PRESCRIBING RIGHTS
Macronutrients – Part 5 in a 6-part series
Dietary Fat – Macronutrient #3 – “Healthy” Fat is Fabulous!
There are a lot of misconceptions around this macronutrient. Many people fear fat. For years, fat was considered a four-letter word. We were urged to switch to low-fat foods and even banish it from our diet. Many survey results suggest that most consumers believe that their fat intake should be as low as possible and that fat is not needed for a healthy diet [1,2]. Despite consumer perceptions, research supports the use of a 20-35 % fat diet [3,4]. All this information leads to confusion about fats, and that is understandable on some level.
So, let’s take a closer look at the different kinds of fats and why this knowledge is important to our overall health.
You may be surprised to hear that fat is the primary source of fuel during fasting, glycogen depletion, insulin deficiency and when you engage in low-intensity movements including sleeping at night, sitting at your work desk and casually walking a dog. The body naturally does this to spare our glycogen stores (the golden stuff!) for your brain, higher intensity work and necessary body functions.
Fat is the most calorie dense macronutrient we eat. Each gram of fat, whether it’s a spoonful of almond butter or a sirloin steak, provides 9 calories. This is more than twice the calories in carbohydrates and protein. In other words, you can eat twice as many carbs or proteins as fat for the same number of calories. Each macronutrient has its place in a healthy diet, and the fact that fat contains more calories than carbohydrates and protein doesn’t make it inherently bad.
You can not equate dietary fat to body fat. You can increase your body fat by eating excessive dietary fat and/or by eating excessive carbs and protein, even if you eat very little dietary fat. The body has figured out a way to make fat even if we eat almost no fat at all. It does this by taking excess carbs and protein ingested along with insulin and converts these macro’s into fat and stores it as energy in our adipose tissue. (Spoiler alert: fats themselves do not necessarily make you fat). Too many calories, from any macronutrient, can lead to weight gain – therefore, moderation is the key.
Fun Fat Fact– A typical adult has approximately 50 billion fat cells … which means there are over six times more fat cells in one human body than there are people on the earth.?
What does fat do for us? Why is it so important?
- Our stored fat is our biggest energy reserve
Fat is a major fuel source for our body during inactivity and during exercise performed at or below 65 percent of aerobic capacity. This means that adipose tissue provides a lot of calories at low heart rates. Even at rest, fat contributes 50 percent or more of the fuel that muscles need, therefore slowing the use of our limited glycogen stores during low intensity activity and rest. (See table 1). Fat aids endurance by sparing glycogen reserves. Generally, as the duration or time spent exercising increases, intensity decreases (making more oxygen available to cells), and fat becomes the more important fuel source. Stored carbohydrate (muscle and liver glycogen) are subsequently used at a slower rate, thereby delaying the onset of fatigue and prolonging the activity. 
|Table 1 – Estimated Energy Stores in Humans|
|Energy Source||Storage Site||Approximate Energy (Kcal)|
|Fat||Serum free fatty acids||7|
|*ATP/CP = adenosine triphosphate/creatine phosphate|
- Dietary fat supplies the body with essential fatty acids, (EFA’s)
These are special types of “good fat”. Think omega-3 fatty acids!! EFA’s offer the crucial DHA and EPA primarily found in fish.
- Protects vital organs and is insulation for warmth
Some degree of fat on the body is healthy and necessary. It protects our vital organs by providing physical cushioning and stability and helps us maintain a constant core temperature.
- The backbone to important hormones
Cholesterol is what we call the par