Calorie Restriction for Endurance Athletes: Why It’s Not Always A Good Idea

What Is Intermittent Fasting?

Intermittent fasting (IF) is defined as a period of time during which one does not consume any food or drink except water. IF is used to lose weight, improve health, and increase athletic performance. Some studies have shown that IF improves insulin sensitivity, increases fat burning, decreases appetite, reduces blood sugar spikes after meals, and boosts mental alertness.

The Benefits Of Intermittent Fasting For Women

Intermittent fasting may be beneficial for women because it helps them lose excess body fat while maintaining their lean muscle mass. According to some research, IF can help women lose up to 3 pounds of body fat per week!

Women who are trying to gain muscle mass tend to eat more calories than men, but they don’t burn off those extra calories as quickly. They may end up gaining too much body fat. IF allows women to eat less and still maintain a healthy weight.

According to the National Institutes of Health, women need about 2,000 fewer calories per day than men in order to maintain their current body weight.

Let’s say a woman who practices IF eats 1,000 calories per day. If she eats 1,000 calories per day while not practicing IF she might gain weight because the body may think it is starving. The body may store the energy from food as fat in order to “protect” itself.

However, the same woman could eat 1,000 calories per day while practicing IF and lose weight.


Because the act of fasting turns on a process called autophagy. During autophagy the body breaks down and removes waste, such as mitochondria. The mitochondria are the “powerhouses” of the cells. When they start to malfunction the body cannot burn off fat as easily. By fasting, the body starts to burn off excess waste within the cells, which in turn improves how the body processes and uses energy.

The Downsides Of Intermittent Fasting For Women

There are some potential downsides of IF for women as well. For one, women often have a harder time building and maintaining muscle than men. IF may make this problem worse by decreasing a woman’s desire to strength train.

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This is not always the case, however. Some women may perform resistance exercise while practicing IF and find that their strength actually increases. In order to get the most out of your IF routine, you may choose to strength train during your feeding window only. You may also want to perform high intensity interval training (HIIT) during your feeding window.

The other big concern for women is fertility. For some reason, intermittent fasting tends to reduce a male’s fertility but it tends to reduce a female’s even more. If you’re a woman who wants to have children in the near future, you may want to avoid intermittent fasting altogether.

I personally practice IF on and off. I’ll go weeks eating all of my calories within a 6 or 7 hour window and then I’ll go weeks without restricting my eating window at all. I don’t track calories either. I just eat when I’m hungry and stop when I’m full.

For women who want to gain muscle, lose fat, improve athletic performance, and maintain fertility, it may be best to perform HIIT during your feeding window only. You should eat plenty of nutritious foods, get enough high quality sleep, and strength train 3 to 4 times per week.

If you can afford the time, you may also want to consider implementing a constricted feeding window as well.

Research has shown that eating a large breakfast containing mostly protein and fat increases metabolic rate and promotes fat burning. Eating a large breakfast has also been shown to improve cognitive performance, reduce food cravings, and regulate the hormones that affect hunger.

If you are going to implement a feeding window, eating a large breakfast is a good place to start. The morning is the best time to eat because your body hasn’t had anything to eat or drink for about eight or more hours. Your insulin sensitivity is at its peak while your body’s energy stores are low. In other words, your body is ready to absorb nutrients and utilize them immediately.

The following recipes are high fat, high protein breakfast recipes that you can enjoy during your feeding window. Feel free to portion out your servings and eat them over the course of a couple of hours. Store the rest for later. You may also want to practice cooking everything the night before so that you’re able to quickly reheat things and eat within your feeding window.

Calorie Restriction for Endurance Athletes: Why It's Not Always A Good Idea - Picture

Hard Boiled Eggs


– 6 eggs


Place the eggs in a pot and cover them with water Add 1/2 tablespoon of salt to the water. Bring the water to a boil, then remove from heat, cover, and let sit for 12 minutes. Dump out the water and cover the pot with a lid for about 10 more minutes. Then transfer the eggs into an ice bath to chill.

Ham and Egg Muffins


– 8 slices of ham, chopped

– 1/4 cup of chopped red onion

– 1 cup of chopped button mushrooms

– 6 eggs

– 2 cups of milk (2% or whole)

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Preheat the oven to 350 degrees Fahrenheit. Grease a 12-cup muffin pan. In a large pan, heat a little oil over medium-high heat and cook the ham until it starts to brown. Add in the mushrooms and onions and cook until the mushrooms begin to release their juices.

In a large bowl, whisk together the eggs and milk. Stir in the ham and mushroom mixture. Fill the cups in the muffin pan 3/4 of the way full with the egg mixture. Bake for 20-30 minutes or until the tops are firm.

Oatmeal with Peanut Butter and Banana


– 1 cup of oats (quick or old-fashioned)

– 2 tbsp of peanut butter

– 1 large banana, sliced


Cook the oats however you normally would. Add the banana and peanut butter before serving. You can also add any other toppings you like, such as honey, flax seed, or cinnamon.

Beef and Vegetable Burger

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1 lb of lean ground beef

½ cup of finely chopped onion

2 tbsp of seeded and finely chopped jalapenos (use less for a milder flavor, or more for extra heat)

¼ cup of flat-leaf parsley, finely chopped

3 cloves of garlic, minced

2 tsp of salt

¼ tsp of pepper

1 large egg

¼ cup of whole-wheat breadcrumbs

2 tsp of olive oil


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In a large bowl, combine the beef, onion, jalapenos, parsley, garlic, salt, and pepper. In a small bowl, lightly beat the egg. Add the egg to the beef mixture and combine well. Shape into 6 patties and coat with breadcrumbs.

In a large skillet, heat the oil over medium-high heat. Place the patties in the pan and cook for about 5 minutes per side for medium.

Tip: Serve on a Kaiser roll with butter lettuce, tomato, onion, and mayonnaise.

Cottage Cheese and Fruit

Blend together:

1 cup of low-fat cottage cheese

1 cup of fat-free Greek yogurt

1 tsp of cinnamon

¼ cup of honey (or your preferred sweetener)

Stir in 1/2 cup of your favorite berries.

Snack Option 1: Greek yogurt mixed with fruit, such as blueberries or raspberries.

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Snack Option 2: Trail mix. Mix together ¼ cup of raisins, ¼ cup of peanuts, and ¼ cup of m&m’s (plain or peanut).


Southwestern Chicken Wrap


4 oz of cooked and shredded chicken (breast or thigh)

2 large tomato slices

2 tbsp of shredded lettuce

1/3 cup of fat-free ranch dressing

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1 large flour tortilla (8 inches across)

1 cup of salsa (sugar-free)


Place the tortilla flat on a plate and coat with the salsa. Place the chicken in the center of the tortilla and top with the tomato and lettuce. Fold the bottom of the tortilla up over the filling, then fold both sides toward the middle and finish rolling until completely wrapped. Cut in half on a diagonal and enjoy!

Tip: If you don’t have cooked chicken on hand, poach 2 chicken tenders in a pan with water or chicken broth for about 15 minutes—or until cooked through. Then shred or cut into small pieces to serve.

Dietitian’s tip: Look for wraps that are around 100 calories, especially if you’re planning on having a second wrap. If you’re not, aim for those that are around 120 calories.

Sources & references used in this article:

Calorie Restriction for Endurance Athletes: Why It’s Not Always A Good Idea by G Turner, ES Triathlon –

Effects of long-term calorie restriction and endurance exercise on glucose tolerance, insulin action, and adipokine production by L Fontana, S Klein, JO Holloszy – Age, 2010 – Springer

Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes by C Zinn, M Wood, M Williden, S Chatterton… – … Society of Sports …, 2017 – Springer