A lot of us have been taught to think that fats, in general, are harmful. Even considering how we look, we connect consuming fats with gaining weight—and many individuals view this as a disadvantage for athletic abilities.
However, it is a fact that fats have an important function in nutrition. They store energy, facilitate the absorption of vitamins, provide insulation, and contribute to athletic performances, especially endurance sports that involve lower intensities.
What are fats, exactly
Fats, along with protein and carbohydrates, are the third macronutrient that we consume in our diets. Among the three, fats are the most energy-dense as they contain 9 kcal per gram, while carbohydrates and proteins contain 4 kcal per gram of nutrients.
Even though fats are calorie-dense, they undergo oxidation at a slower rate compared to carbohydrates. Hence, our bodies rely on carbohydrates for quick energy when necessary, such as during high-intensity sessions. However, fats play a critical role in slow and steady-state forms of exercise.
Categorizing fats for sports
Burke states that previously, saturated fats were regarded as separate from mono- and polyunsaturated fats. However, there is now an understanding that there is some overlap even within these groups. The aim of establishing population guidelines for fat intake is to ensure a balanced distribution of fat consumption across different types, avoiding excessive amounts of certain types.
According to Burke, the beneficial factors are monounsaturated fats and small quantities of polyunsaturated fats. However, what truly makes a difference is not solely the fats, but rather the types of food in which they are found.
Burke recommends obtaining fat from nutritious food sources and incorporating a range of sources into your daily fat consumption. This approach enables consideration of not only the fats themselves, but also the diverse array of nutrients that may be present in the same food simultaneously.
Burke states that dairy products, meat, fish, poultry, as well as certain fruits, vegetables, nuts, avocados, and seeds are good sources of fat. Despite containing saturated fats, these foods have a beneficial composition. In contrast, consuming them with biscuits, crisps, or heavily processed food significantly reduces the overall nutritional value of the fat.
What percentage of fat should we eat
According to Burke, finding the correct equilibrium between the overall calorie count and the proportion derived from various nutrients can be challenging. The amount of calories consumed in a single day can vary significantly depending on one’s energy needs for growth or the type of physical activity being performed.
It is possible for two individuals to consume the same amount of fat grams per day. However, the percentage of fat intake relative to their total daily caloric intake may differ. For one person, consuming that amount of fat would constitute 10 percent of their daily caloric intake, whereas for the other person, it would be 20-25 percent. As long as these percentages align with the respective athletes’ goals, both are acceptable.
To work in a systematic manner, Burke uses grams of macronutrients per kilogram of body weight per day instead of focusing on a specific percentage. Typically, she determines the quantities of carbohydrates and proteins first, and then addresses the fat needs.
Additionally, she utilizes a periodized approach in her work, wherein she takes into consideration various factors such as her athletes’ sessions (differentiating between high-intensity and low-intensity sessions), their weekly schedule, goals, timing within the year, among others, to determine their specific requirements.
If an athlete’s goal is to lose weight, is there a way to do it in a healthy and sustainable way? And does that involve cutting fat intake?
According to Burke, there may not be a universal method that guarantees success for all athletes at all times. However, she believes that when it comes to lowering energy intake, it is often more convenient to decrease fat consumption in order to create a greater energy deficit.
In addition, there could be more precise tactics focused on metabolic interventions that activate metabolic benefits, particularly enhancing fat metabolism, which is vital for enduring performances.
There are two methods that involve adjusting eating patterns: fasted training, where athletes exercise in the morning without having breakfast, and time-restricted feeding, which aims to limit the duration of daily eating by finishing meals early in the evening and starting them later in the day.
Explaining the concept of time-restricted feeding, she suggests implementing a time limit wherein one would only consume food from 10 in the morning until 7 in the evening. By doing so, the duration of food intake is reduced, while the fasting hours are increased.
Body fat stores and endurance exercise
In comparison to our glycogen reserves, our stores of body fat (triglycerides) are significantly larger.
Our body stores this primarily in our adipose tissue, which refers to the body fat under our skin and around our vital organs. Additionally, it is also stored as essential fats, such as omega-3 and 6, in various parts of our body including the brain, nerves, bone marrow, and organ and cell membranes. Furthermore, intramuscular triglycerides exist as fat droplets stored within our muscle fibers.
In the cytoplasm, there is a supply of lipid stored which is easily accessible for aerobic metabolism in the mitochondria. It is noteworthy that intramuscular triglycerides are utilized at greater rates compared to triglycerides released from adipose tissue.
For endurance athletes, it is vital to maintain these stores.
A key point to consider is that decreasing the percentage of fats in our diet, such as following a high-carbohydrate diet that lowers it to 20% or below of total calories, can lead to a notable decrease in fat stores, especially those found within the muscles.
Endurance exercise performance could potentially be affected by this. Specifically, endurance athletes might experience a decrease in intramuscular triglyceride levels when following a low-fat, high-carbohydrate diet.
Intramuscular triglyceride (Fat) stores and endurance exercise
During exercise, intramuscular triglyceride stores can provide approximately 2,000-3,000 calories, which is significantly more than the glycogen stores of most athletes. The capacity of glycogen stores to supply energy ranges from 1,200 to 2,000 calories, depending on factors such as body size, training history, and carbohydrate intake.
Intramuscular fat stores are found within your muscle fibers, specifically in larger amounts within type I (slow oxidative muscle fibers). This is not surprising because fat metabolism mostly takes place within the mitochondria of slow twitch muscle fibers.
We are of the belief that intramuscular triglycerides provide approximately 50% of the total fat calories during moderate intensity exercise, which equates to approximately 25% of the total calories.
In addition to endurance training inducing heightened intramuscular fat stores, it also promotes increased utilization of fat during endurance exercise. Notably, resistance and sprint training also result in augmented intramuscular breakdown and utilization.
Just like muscle glycogen, the levels of intramuscular triglycerides decrease after endurance exercise. Additionally, engaging in prolonged endurance exercise for approximately 2 hours or longer will result in a substantial decline in our intramuscular triglyceride reserves.
When we participate in prolonged exercise for multiple days, we worsen this situation. Additionally, once the intramuscular stores are depleted, they can stay depleted for several days.
High-Carbohydrate diets may impair replenishment of intramuscular fats
A high carbohydrate/low-fat diet (~62% carbohydrate and 24% fat) has been observed by researchers to hinder the replenishment rate of intramuscular triglycerides when compared to a carbohydrate/fat proportion that is more typical.
To counteract this, we should ensure that our fat intake falls within the “normal” range recommended for a healthy adult.
In maintaining the rate of intramuscular fat replenishment, we can also achieve this by following this approach. Additionally, a high-fat diet can increase muscle triglyceride stores in type I and type IIa fibers by approximately 50-75%. Moreover, it can enhance the rate of intramuscular triglyceride breakdown/metabolism, particularly in type IIa fibers.
Maintaining sufficient fat intake is important
This demonstrates that increasing the amount of dietary fats to match those consumed in a traditional diet could have advantages for endurance. This is because it helps to sustain the breakdown of intramuscular triglycerides, even when in a state of high carbohydrate intake.
Additionally, it is worth noting that individuals who engage in approximately 5 hours of exercise per week at 70-85% of their maximum heart rate can adequately maintain muscle glycogen levels with a diet consisting of only 50% carbohydrates.
Fat intake and endurance exercise performance
Although consuming a higher proportion of fat calories compared to the traditional high-carb low-fat proportion seems to have training benefits, it is uncertain whether a high-fat diet before endurance competition is advantageous, according to current research.
Research has failed to find improved exercise performance despite the knowledge that a high fat intake can increase the mobilization and metabolism of free fatty acids.
Most of the studies examining the impact of a high-fat diet on exercise performance have used small amounts of carbohydrates. This could have led to decreased levels of muscle glycogen and subsequently restricted exercise performance.
During a study, researchers examined how consuming a high-fat meal before exercise, followed by a small amount of carbohydrate jelly, affected individuals in a state of carbohydrate loading. The researchers discovered that when combined with three days of carbo loading, the pre-exercise high-fat meal and carbohydrate jelly improved endurance performance in running.
The athlete must be in a carbo-loaded state for them to determine that this is a beneficial nutritional strategy for a marathon race.
Moderate the intake of saturated fats
It is important to note that while the amount of fat consumed may need to be higher than in a regular diet, it is crucial to keep the level of saturated fat within the range of a normal healthy diet.
It is advised that a regular, healthy diet should not exceed 30g of saturated fat in a day. This guideline should also apply to endurance athletes. If you want to increase your fat consumption without a substantial increase in saturated fats, you might consider incorporating nutritious alternatives.
- Unprocessed vegetable oils such as extra virgin olive oils.
- Cold pressed sunflower oils and olive oil spread instead of margarine.
- Aim to consume 2-3 portions of oily fish per week, (mackerel, herring, sardines, etc) as these contain the important essential fatty acids omega-3 which are vital for heart health, good circulation, mobility of joints, and may have positive effects on fat metabolism.
- Some other excellent sources of healthy fats include olives, mayonnaise, some types of nuts (almonds, walnuts, and Brazil nuts), and seeds (sesame, sunflower, pumpkin).
- You may also wish to consider taking fish oil capsules (containing high concentrations of the important Omega-3 fatty acids EPA and DHA) to ensure you are getting an adequate supply of these important substances.
