Fats role in Plant-Based Nutrition and Endurance Athletics; Part 2 of 2
Updated: Oct 25, 2019
You can read Part 1 of 2 on Fats HERE:
Metabolism of macronutrients was touched on in the carbohydrate articles. Let’s talk about metabolism of fats and the logistics around this happening. Although fats are a very powerful and useful energy source for all athletes both omnivorous and plant-based, there are several rules that we have to remember which should be reflected by our dietary choices.
"There is little to no evidence suggesting that high-fat diets improve athletic performance, increase endurance, aid in weight loss or improve recovery."
Fat burns in the flame of carbohydrates. This means that even the most fat adapted athletes need to consume some carbohydrates to utilize their endogenous fats as energy. In order to utilize fats as energy, we need carbohydrates as a puzzle piece to make this happen [Benardot].
Fatty Acids can only be metabolized aerobically. Aerobic is ‘using oxygen’. We’ve all felt that ‘muscle burn’ feeling. It’s when we shift from aerobic to anaerobic and start feeling that ‘muscle burn’. That muscle burn is lactic acid which is a metabolic byproduct of anaerobic glycolysis, something that will be covered in future articles. Anaerobic means ‘without oxygen’. We’re exercising at such a high intensity, that our muscles’ demand for oxygen is above what our bodies can supply. Thus, our physiologic engine starts to produce energy anaerobically. The downside is that the byproduct of anaerobic glycolysis is lactic acid and during this process our bodies are using predominantly carbohydrates instead of fats. Remember, the higher the exercise intensity, the lower the percentage of fats the body uses.
Maximal fat oxidation occurs at 60-65% VO2 max. This means that when we’re exercising at a moderately high intensity, we’re using quite a bit of fat for muscle contractions. Again, this is still within the aerobic zone.
The proportion of fat burned should not be confused with the total volume of fat burned. This applies to the notion that if we exercise at a lower intensity, we’re burning more fats which is a desirable outcome if we’re looking to lose weight. For example, when we exercise at 30% VO2, we’re burning a much larger proportion of fat for energy because it’s very much aerobic. One may argue that when we increase our intensity to 70% VO2, we’re burning less fat because as our intensity goes up, our reliance on carbohydrates goes up and reliance on fats goes down. To a degree, we would be burning a greater percentage of carbs, but the flaw in this thinking is not realizing the distinction between proportion of fat and total volume of fat. Although the proportion of fat being metabolized at a lower intensity (30% VO2) is higher, the total volume of fat being metabolized is higher when we exercise at a higher intensity because our body’s demand for energy is greater. So if we want to burn the most volume of fat, exercising at around 60-70% VO2 is the most efficient zone. In simple terms, exercising at a pace where you can still carry on a conversation is probably Low Intensity. A pace where it’s hard to have a conversation is most likely moderate- Shoot for this zone. If you’re feeling too much muscle burn, back off, you’re passing into the anaerobic zone.
Fat oxidation cannot be improved to the point of eliminating the need for carbohydrates during intense exercise. We can certainly improve the efficiency of our bodies to use fat as a fuel source. Training can allow us to use more fat at higher intensities so that we can conserve valuable carbohydrate stores for when we really need them, like at the end of a race for the sprint. But, we can never eliminate carbs from our diet.
Because there is so much energy contained within fats, there is a growing interest in having athletes take in more fats to improve athletic performance and act as an ergogenic aid. After reading several review articles, the results of studies published do not show a clear benefit. Results are mixed, at best, and the body of evidence shows that eating high fat diets (60%) are detrimental to performance . Beyond 4 weeks, high fat consumption has been shown to have a definitive detrimental effect on endurance [Eberle]. She includes that, in theory, ultra-endurance athletes, exercising at relatively low percentages of VO2, may benefit from eating more fat or ‘fat loading’, but also adds that studies have not shown a statistically significant effect. An important factor to consider is that high fat diets squeezes carbohydrates out of the mix and lowers glycogen stores. Eberle adds that increasing fat Increases the risk for heart disease, certain cancers, and cyclists saw an increase in their cholesterol on a high fat diet. Conversely, no source advocates eating zero fat and for endurance athletes burning 4000+ calories per day. Eating fat provides more energy per pound, which may be advantageous for those struggling to get in enough calories [Eberle]. In an editorial in the Journal of Applied Physiology, the authors state “Those at the coal-face of sports nutrition can delete fat loading and high-fat diets from their list of genuine ergogenic aids for conventional endurance and ultra-endurance sports...The strategic activities that occur in such sports, the breakaway, the surge during an uphill stage, or the sprint to the finish line, are all dependent on the athlete’s ability to work at high intensities…” and there is “growing evidence that this critical ability is impaired by dietary fat adaptation strategies.” In other words, if you’re a competitive cyclist, triathlete, swimmer or an athlete who needs to ‘surge’ at any time in the race, a high fat diet is not the way to go.
One aspect of dietary fat consumption that has been shown to have beneficial properties for endurance athletes, especially those on a plant-based diet, is essential fatty acid consumption. Additionally, there is growing concern that those eating a predominantly plant-based or vegan diet won’t get enough of these essential fatty acids as these fats are widely assumed to be only in animal foods, namely oily fish. There are 2 essential fatty acids, Omega 3 (linolenic acid) and Omega 6 (linoleic acid). Like essential Amino Acids, we need to consume essential fatty acids from our diet, our bodies cannot synthesize them. One must consider the ratio of Omega 3 to Omega 6. “We’ve seen major changes in the amount of fat and the type consumed in the past 150 years, but our genetics have not changed” . The western diet is rich in Omega 6’s, which in high quantities have been shown to increase inflammation, increase the risk for blood clots, increase the viscosity of blood and vasoconstriction [76[. Conversely, the SAD diet is quite low in Omega 3, which is quite anti-inflammatory, leads to increased production of endogenous antioxidant enzymes, increase oxygen delivery to the heart  and improves aerobic metabolism . There is a an amount and ratio that we should adopt when it comes to these Omega FA’s. Ratios in the literature of Omega 6’s to Omega 3’s are 1:1 , 2:1 or even 3:1 . But these ratios are very different than what Americans are consuming, which are closer to ratios of 10:1 or 20:1 . The Acceptable Macronutrient Distribution Range for Omega 6 is 5-10% of total calories, or 11-22g/day. For Omega 3 it’s .6-1.2% of daily calories, or 1.3-2.6g/day . for Sources of Omega 3’s and Omega 6’s are included in a graph, courtesy of Ryan .
Because there is so much energy contained within fats, there is a growing interest in having athletes take in more fats to improve athletic performance and act as an ergogenic aid. After reading several review articles, the results of studies published do not show a clear benefit.
There is a subset of Omega 3 fatty Acids that “are of great interest to health experts and to endurance athletes”. These are abbreviated EPA and DHA , and are difficult to find in grocery store foods. The third subtype of Omega 3 is abbreviated ALA which is in sufficient quantities in many easily found plant-foods. Dr. Artemis Simopoulos, MD in his paper on Omega-3 Fatty Acids and Athletics stated that supplementation of EPA and DHA for elite athletes are essential . EPA/DHA have the same general effects on the body as Omega-3’s. The reason why these two Omega-3 FA’s are of particular importance is because the body may have a difficult time producing them and will have an even harder time finding native EPA and DHA from grocery store whole plant-foods.
The body can can produce EPA and DHA from sufficient quantities of ALA, but some “individuals do not self-produce ideal levels of DHA and EPA even when proper attention is placed on obtaining sufficient ALA .” Because of this, Furhman  suggest supplementation of DHA, and for plant-based or vegan athletes, algae-based DHA. What about supplemental EPA? The body can readily convert ALA to EPA and can undergo retroconversion to turn DHA to EPA, therefore supplementation of EPA is not necessarily recommended. Dr. Michael Greger in his Optimum Nutrition Recommendations suggests supplementing with 250mg of DHA/EPA.
"Fat burns in the flame of carbohydrates. This means that even the most fat adapted athletes need to consume some carbohydrates to utilize their endogenous fats as energy. In order to utilize fats as energy, we need carbohydrates as a puzzle piece to make this happen."
There is little to no evidence suggesting that high-fat diets improve athletic performance, increase endurance, aid in weight loss or improve recovery.
Fats are important. Plant-based athletes shouldn’t be afraid of plant-based sources of fats and they should not make a conscious effort to limit them.
Some fats have been shown to be beneficial to the body, whereas some have been shown to be detrimental. If we consume animal products to benefit from certain nutrients (i.e protein, iron etc) we inevitably consume many unhealthy fats. Understand that we can consume healthier foods that contain the nutrients we’re looking for AND healthy fats at the same time. It's a triple win: Beneficial nutrients, beneficial fats and no harmful fats.
Consider supplementing with Algae-based DHA. This would ensure more advantageous levels of EPA and a better ratio of Omega 6 to Omega 3. Add plant-based sources of Omega-3 Fatty acids a regular part of your daily diet.
What do you think?
Are you, or were you, scared of fats? Did you tend to shy away from them?
How will these articles on fat influence your dietary habits?
Questions? Comments? Let me know below or reach me on social media.
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