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.😊[9]

What does fat do for us? Why is it so important? 

  1. 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. [5]

Table 1 – Estimated Energy Stores in Humans
Energy Source Storage Site Approximate Energy (Kcal)
ATP/CP* Various tissues 5
Carbohydrate Blood glycogen 80
Liver glycogen 400
Muscle glycogen 1,500
Fat Serum free fatty acids 7
Serum Triglycerides 75
Muscle triglycerides 2,500
Adipose tissue 80,000+
Protein Muscle protein 30,000
*ATP/CP = adenosine triphosphate/creatine phosphate

 

  1. 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.

  1. 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.

  1. The backbone to important hormones

Cholesterol is what we call the parent hormone – it’s the backbone on which progesterone, DHEA, testosterone and our estrogens are made from.

  1. Fat is important in brain health

Fat surrounds neurons and allows electrical signals to flow efficiently, giving us the ability to think and act quickly. 60% of our brain is fat and it’s the quality of healthy fats that are linked to improved cognitive function, not the quantity.

  1. Assists in the absorption of fat-soluble vitamins A,D,E and K

Fat-soluble vitamins will not dissolve in water. Instead, fat-soluble vitamins absorb best when taken with or in higher-fat foods. (We will talk more about these in Part 6 next week)

  1. Maintain cell membranes

Vital for every cell in our body

  1. Maintain healthy blood cholesterol

Knowing which fats lower your bad LDL cholesterol and increase your good HDL cholesterol can help keep your heart and arteries in good health

Foods we eat that are high in saturated and trans fats promote inflammation. It’s best to minimize the amount of these foods

Fun Fat Fact – First the good news…fat cells generally do not increase in number after puberty so even if you gain weight the number of fat cells you have remains the same. Now the bad news… Each fat cell simply gets bigger and can expand up to ten times its normal size. 😊[9]

There is “good fat” (unsaturated fats) and “bad fat” (saturated fats). What are the differences?

A) Good fats – Unsaturated Fat

Unsaturated fats are considered the good“healthy fats” when eaten in moderation. They help increase your good cholesterol – HDL, which lowers your bad cholesterol – LDL. This helps reduce your risk of coronary artery disease and provides many other health benefits. Typically, unsaturated fats are liquid at room temperature (e.g. olive oil). They mainly come from plant-based sources like nuts, seeds, and vegetable oils, as well as fish. They can be further categorized as:

  • Monounsaturated fats (MUFA’s)

This type of unsaturated fat contains only one – mono – double bond in its structure, thus fewer hydrogen atoms. MUFA’s are typically liquid at room temperature and include olive oil, avocados, almonds and cashews. The next time you dip your bread in olive oil at an Italian restaurant, you’re getting mostly monounsaturated fat.

  • Polyunsaturated fats (PUFA’s)– These are essential fat acids (EFA’s)

These are called essential because your body cannot make them itself or work without them. These EFA’s are needed for brain development, blood clotting and controlling inflammation and much more. This type of unsaturated fat contains two or more – poly – double bonds in their structure. They can be liquid at room temperature. Polyunsaturated fats are found in oily fish, nuts and seeds.

There are two main types of polyunsaturated fats:

  1. Omega-3 fatty acids – Key family of polyunsaturated

There are 3 main types of Omega 3 fatty acids:

  • Alpha Linolenic acid (ALA)– Not the most important omega 3, but it is the most common omega-3 fatty acid in most Western diets. It is found in seeds, nut and plant sources such as flaxseed, chia, hemp, walnuts, leafy vegetables, and some animal fat, especially in grass-fed animals.
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

EPA & DHA– Most important and useful essential omega 3 fatty acids. These mainly come from fish, so they are sometimes called marine omega-3s. Examples include salmon, mackerel, sardines, and algae oils. Health Canada recommends at least two servings of non-fried fish per week.

2. Omega-6 fatty acids– Linolenic acid (LA) – found in many plant oils, including palm oil, sunflower oil, flaxseed oil, corn oil and evening primrose oil. Most diets provide adequate amounts of this fatty acid, and therefore planning is rarely required to ensure proper amounts of omega-6 fatty acids.

These unsaturated fatty acids are important to keep your body working like a well-oiled machine. But don’t go overboard. All fats, including MUFA’s and PUFA’s are high in calories, so use them only in moderation. Consume MUFA and PUFA rich foods instead of other saturated fatty foods, not in addition to them.

Fun Fat Fact – there are no fat cells in your eyelids or parts of the esophagus. 😊[9]

B) Bad fats – Saturated Fat and Trans Fat

These are considered unhealthy fats due to their chemical structure. They are common in the American diet. Trans fats are similar in structure to saturated fats. Too much of these two fats can increase the amount of bad cholesterol (LDL) – in our blood. This can lead to heart disease, type 2 diabetes and much more. Trans fats may also raise blood triglycerides and lower our good cholesterol (HDL).

  • Saturated Fat 

These are simply fat molecules that have no double bonds because they are saturated with hydrogen molecules. Saturated fats (butter or cooled bacon grease) tend to be solid at room temperature. Common sources include red meat, whole-milk dairy foods, cheese, and coconut oil.  Currently the American Heart Association (AHA) recommends that between 20 to 35 percent of your total daily calories should consist of fat and less than 5 to 6 percent of that fat should be from saturated fat with the rest being polyunsaturated fats.

  • Trans Fat

These are naturally occurring trans fats and artificial trans fats. Small traces of natural trans fats are produced in animals guts and in turn tiny amounts turn up in foods they create. But according to AHA, we don’t have enough research to determine the impact these types of natural trans fats have on our health. Several review studies have concluded that a moderate intake of naturally occurring ruminant trans fats does not appear to be harmful. [6,7,8]

Fun Fat Fact – pound of body fat is equal to 3,500 calories. To burn off 3,500 calories the average woman would need to do 6 step classes, walk briskly for almost 9 hours or run for 33 miles. 😊[9]

Artificial trans fats – These are the worst type of dietary fat!

While they’re actually unsaturated fats, their chemical structure is changed by a man- made process called hydrogenation, in which hydrogen molecules are added to the unsaturated oil to change them into a solid saturated fat called partially hydrogenated oils (PHO’s). This was done to try and synthesize a cheap, stable, easy to use, long shelf-life and tasty oil – The result was the birth of “The Frankenstein’s monster of fats” – artificial trans fats.

Some common sources of (PHO’s) artificial trans fats are margarine, fast food, coffee creamer, baked goods, crackers, fried potatoes, chips, microwave popcorns, frozen pizza, refrigerated dough products (such as biscuits and cinnamon rolls), and ready-to-use frostings. Many restaurants and fast-food outlets use trans fats to deep-fry foods because oils with trans fats can be used many times in commercial fryers.

GOOD NEWS!  Canada has been trying to ban artificial trans fats, (PHO’s) for 15 years.

Just recently, on September 17th  2018  an important milestone in terms of nutrition policy in Canada occurred; Canada’s artificial trans fats ban came into effect. Retailers will be given a grace period of two years to clear the inventory already on store shelves. Keep watching those nutrition labels – it will be roughly two years before all PHO’s are eliminated in Canada … that’s pretty significant!

Note – fats contain a combination of different fatty acids. No fat is pure saturated fat or unsaturated fat. This is where it is important to read nutrition labels on food. (We will talk about reading food labels in a future article)

So, as you can see, healthy fat is good and necessary in moderate amounts. But, not all fats are equal and some are actually silently harmful to our overall health in the long run. Dietary fat is a confusing concept, with both evolving science and areas that still remain uncertain. Now that we have this background information about fat, in a future post we will look at 2 lipoprotein biomarkers we can obtain from a simple bloodwork panel. We can use this information to optimize our health, athletic performance and prevent an array of illnesses.

References:

  1. Diekman C, Malcolm K. Consumer perception and insights on fats and fatty acids: knowledge on the quality of diet fat. Ann Nutr Metab. 2009;54(Suppl 1):25–32.
  2. International Food Information Council Foundation. 2014 Food and Health Survey: consumer attitudes towards food safety, nutrition
  3. Jensen MD, et al. AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association task force on practice guidelines and the Obesity Society. J Am Coll Cardiol. 2014;63(25 Pt B):2985–3023. n and health. Washington D.C.; 2014.
  4. Estruch R, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013;368(14):1279–90.
  5. Girard Eberle, Suzanne. Endurance Sports Nutrition, 3rd Edition. Champaign: Human Kinetics Publishers, 2014.
  6. Eur J Clin Nutr. 2009 May;63 Suppl 2:S5-21. doi: 10.1038/sj.ejcn.1602973. Health effects of trans-fatty acidsexperimental and observational evidence.
  7. Bendsen NT, Christensen R, Bartels EM, Astrup A. Consumption of industrial and ruminant trans fatty acids and risk of coronary heart disease: a systematic review and meta-analysis of cohort studies. Eur J Clin Nutr. 2011;65:773–783. pmid:21427742
  8. Gebauer SK, Chardigny JM, Jakobsen MU, Lamarche B, Lock AL, Proctor SD et al. Effects of ruminant trans fatty acids on cardiovascular disease and cancer: a comprehensive review of epidemiological, clinical, and mechanistic studies. Adv Nutr. 2011;2:332–354. pmid:22332075
  9. https://www.weightlossresources.co.uk/body_weight/body_fat/fifteen-fascinating-fat-factoids.htm