Updated: Apr 30


Well, depends really how much of it you consume, as with everything else. But it's not so simple as that.

So far we have talked about the popular guy: protein, who builds muscles and helps recovery; and we've talked about carbohydrate, the real boss when it comes to providing energy and optimizing sports performance. Well, there's one guy left, a pretty controversial one, called fat. Once again, the "experts" are divided into those who state that fat makes you fat and you should eliminate it from your diet, and those who promote a high fat, low carbohydrate diet, as the best option. Which leaves the poor mortals desperate and confused. So let's start from the basics.

Different shapes and forms and whatnot

As with everything else, fats (or lipids, as they are formally known) appear in different shapes and forms. The term fat usually refers to lipids that are solid at room temperature, and the term oil refers to lipids that are liquid at room temperature. The one common attribute is that they are soluble in organic solvents, but not soluble in water. Despite the numerous forms of lipids, we can obtain them all through diet and our bodies are also capable of making many types of lipids from other substances. This ability to effectively manufacture different types of lipids, makes it unnecessary to consume large amounts of dietary fats.

Lipids have different levels of saturation (I won't go into the whole story about the double bonds and carbon chains, because this is not a chemistry class). Saturated fatty acids are mostly found in animal products, palm and coconut oil. Monounsaturated fats are highest in olive and canola oil, but are also present in fats of animal origin. Polyunsaturated fats are highest in vegetable oils (with the exception of olive oil).

Saturated fatty acids are associated with higher cholesterol, so they should be minimized when possible. For optimal nutrition in general, most people would benefit from reducing the total intake of fats and increasing the proportion of mono- and polyunsaturated fatty acids. In simple terms this means avoiding most fried foods, high-fat dairy products, processed meats and candy and consuming more fresh fruit, vegetables and whole-grain cereals.

There are also trans fats, used to extend the shelf life of processed foods. I will not go into detail about them here, cause they're just nasty. Try to avoid those guys.

What is it good for?

Loads of stuff, of course! Here's some of them:

  1. A certain amount of fat (20-35%) is necessary to ensure a sufficient energy and nutrient intake

  2. Fat soluble vitamins, like A, D, E and K (these are important, if you were wondering) must be delivered in a fat package

  3. Dietary fats give us a feeling of satiety (creating the important physiological signal that it is time to stop eating) and they also have a longer gastric emptying time, which contributes to the feeling of satiety during the day

  4. Omega-3 and Omega-6 fatty acids contribute to good health and may reduce muscle and joint inflammation; and most importantly

  5. Fat makes food taste good

Fat stores and fuel

Fat is stored in the form of triglycerides, which is manufactured when we consume excess calories. These triglycerides are stored in groups of fat cells (called adipose tissues) and inside muscle cells. Both of these are available as an energy source when needed, but the intramuscular triglyceride is more immediately available. Each fatty acid can be broken apart for the creation of ATP to provide energy for muscular work. Unlike carbohydrate, which can be metabolised both aerobically (with oxygen) and anaerobically (without oxygen), fatty acids can only be metabolised aerobically.

Even the leanest, healthiest athletes have a substantial energy pool of stored fat. The average storage in adipose tissue ranges between 50 000 and 100,000 kcal - enough energy to theoretically walk or run 500 to 1,000 miles without a refueling stop. In addition, athletes store approximately 2,000 to 1,000 kcal of lipids inside the muscle tissue, available as fuel under the proper conditions.

The weirdo who wants to be a carb

Fat stored in adipose tissue is broken down into its components: glycerol and fatty acids. Glycerol is available for all tissues for energy metabolism, while the free fatty acids are transported to the working muscles where they are oxidized for energy. Glycerol can also be burned for energy in the working muscles, or it can be transported through the blood as a source of energy for other tissues. Glycerol is a unique lipid that can be converted into sugar to help sustain blood sugar levels. It is the only lipid that is metabolised like a carbohydrate. It is also an effective humectant (it holds water). This can be useful for endurance athletes in extremely hot and humid environments, when water loss is likely to be higher that the athletes fluid replacement capacity. Adding glycerol to water helps retain more water and allows the athlete to start a competition in a superhydrated state. However, glycerol is now on the prohibited list of the World Anti-Doping Agency, so keep that in mind if competing in a sanctioned event. Being superhydrated is also likely to cause a degree of discomfort (feeling heavy or stiff) that requires adaptation. So the bottom line is: make sure you evaluate the pros and cons before loading up your water bottle with glycerol.

So how much fat should I eat, you ask

Fat is a highly concentrated source of energy, providing 9 kcal per gram. A small volume of fat goes a long way toward increasing caloric delivery.

The recommended daily fat intake for adults is 20-35% of total calories, and there is no scientific information suggesting that more than 25% is generally better for athletes, or does anything to improve athletic performance, body composition or weight. However, for athletes who have difficulty sustaining weight because of a massive energy expenditure (like cross country runners) or because they must sustain high weights (football linemen or sumo wrestlers), higher fat intakes (up to 35%) may be useful for satisfying energy needs. So even though increased fat consumption will not directly result in improved performance, for some athletes it can still be beneficial, if it is the only means to obtain sufficient energy. For example and athlete who needs more that 4,000 kcal per day (yes, that's four thousand, you read it right) to meet the combined demands of growth, exercise and tissue maintenance, might need a moderate increase in fat consumption in order to satisfy these requirements. Since fat is a more concentrated form of energy than carbohydrate or protein, more energy can be consumed through a smaller serving, if it contains more fat. The alternative of this would be an inadequate energy intake, which has its own set of negative consequences.

On the other hand, when reducing fat intake (in order to allow the consumption of more protein and carbohydrate to satisfy energy needs), a conscious effort should be made to provide enough total energy. Since fat has more than twice the caloric concentration of both protein and carbohydrate (9 kcal per gram, compared to 4 kcal per gram), more than twice the volume of food must be consumed to make up for the difference. Doesn't sound too bad to me...

Essential fatty acids (the BCAAs of fats)

Just as essential amino acids, there are also essential fatty acids. These are required for metabolic processes, but we are incapable of synthesizing them, so they must be consumed in the foods we eat. So who are these guys? I'm sure you've heard of them: omega-3 and omega-6 fatty acids. Omega-6 fatty acids are required for normal skin health, while omega-3 is necessary for neural function and growth. Both are easily obtained from vegetable oils and fatty cold-water fish.

There are some added benefits of omega-3 fatty acids for athletic performance, including:

  1. Improved delivery of oxygen and nutrients to muscles and other tissues because of reduced blood viscosity

  2. Improved aerobic metabolism because of enhanced delivery of oxygen to cells

  3. Improved release of growth hormone (somatotropin) in response to exercise, sleep and hunger, which may have an anabolic effect or improve post-exercise recovery time

  4. Prevention or reduction of inflammation, which may also speed up post-exercise recovery

Even though studies have not found any consistent improvements in strength and endurance from consuming omega-3 fatty acids, the enhancement of aerobic metabolic processes is still an important factor in both athletic performance, and the ability to effectively burn fat for fuel. These oils have also been shown to decrease the chance of unwanted blood clots and reduce the risk of heart attack.

The recommended standard for omega-3 fatty acid intake for athletes is approximately 1 to 2 grams per day. Good food sources of omega-3 fatty acids include: fatty cold-water fish (salmon, tuna, Atlantic herring), seeds and nuts, flaxseed and flaxseed oil, soybeans and soybean oil. Good food sources of omega-6 fatty acids are: sunflower oil, sesame oil, hemp oil, pumpkin oil, soybean oil, walnut oil.

Exercise intensity and fat burn - back to the eternal debate: LSD vs HIIT

In a previous article (you can read it here) I have talked about the eternal debate between long slow distance training (LSD) and high intensity interval training (HIIT) in the context of improving cardiovascular endurance. The same debate arises when it comes to fat burn, and here's why: the lower the exercise intensity, the greater the proportion of fat burned to satisfy energy needs. As exercise intensity increases, the proportion of fat burned decreases and the proportion of carbohydrate burned increases. This is a fact. A highly misunderstood fact, which explains why so many people perform low intensity activities to burn fat. However, the proportion of fat burned should not be confused with the total volume of fat burned. As exercise intensity increases, the total number of calories burned per unit of time also increases. Although there is a decrease in the proportion of fat burned in higher intensity activity, the total volume of fat burned is greater, because the total energy requirement is higher. Exercising at lower intensities burns a greater proportion of fat, but a lower volume of fat than exercising at higher intensities. Athletes interested in lowering body fat should exercise at least as high as 65% of VO2 max to optimize the total amount of fat burned.

Athlete conditioning and metabolising fat

Improving athletic endurance increases both the number and size of mitochondria, which increases the capacity of the athlete to use a greater amount of fat during physical activity. Since we are able to store far more fat calories than carbohydrate calories, increasing the ability to use fat as fuel leads to a proportionate reduction of carbohydrate reliance, thereby increasing endurance. Put simply, if you can burn a greater volume of fat at higher exercise intensities, you can make your carbohydrate stores last longer, and so your endurance improves. It is important to note that fat oxidation cannot be improved to the point of eliminating the need for carbohydrate during intense exercise. This is also not a reason to increase the proportionate intake of fat. Assuming an adequate caloric intake, athletes can manufacture and store the fat they need, and higher intakes of dietary fat can be a risk factor for heart disease. Even a short-term (3-5 days) increase in fat intake and decrease in carbohydrate intake leads to a reduction in endurance performance when compared to a high carbohydrate intake. This means that the only way of improving the body's ability to use fat as fuel is doing some serious endurance training. Sorry guys, no easy way out here.

If you're looking for inspiration, next week I will share with you my favourite high intensity running intervals that will get your heart rate up in the right place for some serious fat burn, while improving cardiovascular endurance and ensuring you'll never gas out in the ring.


-Fats come in different shapes and forms. Mono- and polyunsaturated fats should make up the majority of fats consumed

-Fat is a highly concentrated source of energy, providing 9 kcal per gram. That's more than twice the amount provided by both carbohydrates and proteins (4 kcal per gram). Bear that in mind when adjusting the proportion of macronutrients in your diet.

-Fats are important for ensuring a sufficient energy and nutrient intake, contribute to the feeling of satiety and, most importantly, make food taste good.

-Some vitamins are only soluble in fat. Vitamins are good. So don't eliminate the fat.

-Fat can only be metabolized aerobically (there has to be sufficient supply of oxygen - low intensity training).

-Fats should make up around 25-35% of total calories consumed. Consuming more than this will not result in improved athletic performance and can lead to a decreased endurance if it replaces carbohydrates.

-The only valid reasons for a moderate increase in fat consumption are: a) being a sumo wrestler and b) not being able to provide adequate caloric intake to sustain extremely high energy demands. Consuming more fat than recommended is still better than not consuming enough total calories.

-Omega-3 and omega-6 are essential fatty acids - make sure you include them in your diet for nice skin, good neural function and growth, as well as improved aerobic metabolism and better recovery. Simply put: eat some fish.

-If your aim is to burn fat through exercise, don't fall for the "low intensity burns fat" myth. Lower intensity = greater proportion, but a lower total volume of fat burned. Exercise at a minimum of 65% VO2 max to optimize fat burn.

-The better your body gets in metabolizing fat for fuel, the longer your carbohydrate stores are going to last and your endurance will increase. This can only be achieved through endurance training.