Fat is one of the most important nutrients and a great supplement especially with exercise. One gram of dietary fat equals nine calories, and one pound of stored fat gives about 3600 calories of energy. This calorie amount (the highest among all nutrients) makes it our biggest energy reserve.
These calories are easy to get for athletes doing quick and intense efforts like running or weightlifting. But fat is key for longer, slower, less intense endurance workouts like cycling and walking.
What dietary fats are:
Everything we eat is made of macronutrients (protein, carbs, fats) and micronutrients (vitamins, minerals) that turn into energy inside the body, helping all body functions. But many think some fats cause health issues, while in truth fats are essential for good health. Fat tissue (stored fat) cushions and insulates organs, protects nerves, carries certain vitamins (A, D, E, K) around the body, and is the largest stored energy reserve for activity.
How does the body use fat for fuel?
Fat is a major fuel source for long, low to moderate intensity exercise. Even during high intensity workouts where carbs are the main fuel, the body needs fat to help access stored carbs (glycogen). But using fat for energy isn’t simple. It has three main parts:
- Digestion: Fat is slow to digest and turns into a usable form of energy. This process can take six hours.
- Transport: After fat breaks down in the body, it takes time to move it to the muscles before it can be used for energy.
- Conversion: Turning stored fat into energy needs a lot of oxygen, so exercise intensity must be lower.
So athletes need to be careful about when and how much fat they eat. Generally, it’s not good to eat fatty foods right before intense exercise. Doing that can cause nasty stomach issues like nausea, vomiting, and diarrhea.
High-fat diet:
Common low-carb, high-fat diets like keto and paleo work the same way. The idea is that eating low carbs, lots of fat, and moderate protein makes your body burn fat as the main fuel when working out.
There is actually some scientific evidence that low-carb, high-fat diets are safe long-term and might help improve metabolic risk factors for chronic diseases. Studies show these diets help performance in endurance sports, but you need at least a few months adapting to a low-carb, high-fat diet for metabolic changes to happen.
