Maintaining Weight and Nutrients as an Athlete with IBS/IBD

Maintaining Weight and Nutrients as an Athlete with IBS/IBD

Published on Tuesday, May 23, 2023 by Kari Tallent

Planning goes a long way when you are working hard on your fitness goals.

As an athlete, it is imperative to not only have a training plan but to also follow a diet that fuels you properly to support your training. Inappropriate fueling can lead to big deficits in your performance as well as your recovery. This can be even more challenging when you suffer from IBS/IBD or runners' colitis. When designing a plan for energy intake you have to consider everything that goes into your total daily energy expenditure.

TDEE or Total Daily Energy Expenditure is a combination of your basal metabolic rate (BMR) and other factors. Other energy expenditure comes from the thermic effect of food (TEF), and physical activity energy expenditure (PAEE). The TEF and PAEE are added to the BMR to get a caloric range to work with when planning an athlete’s diet. Keep in mind that as a training cycle changes so does the caloric volume.

Another factor to consider if you have IBS/IBD or runners' colitis is what your triggers are if you have determined them, and the frequency of flare-ups. Keep in mind your ability to absorb nutrients during a flare-up is going to be limited until your GI tract recovers. Speaking from experience it can sometimes take up to 2 days after a flare-up to fully recover. Depending on the severity it may take longer. 

When this occurs you will have to decrease your PAEE so you are not losing significant amounts of weight and or muscle. When adequate calories aren’t consumed, or able to be absorbed, and you are already maintaining a very lean body mass your body will break down muscle to use as energy. This kind of defeats the purpose of all that effort you are putting into training. You want to focus on Macronutrients- large molecules that are made up of calories.

So how do you get back on track when your gut knocks you down? 

You want to focus on Macronutrients, which are large molecules that are made up of calories. You are going to have to increase your calorie intake to account for weight regain. 

A good place to start is with Carbohydrates. We store carbohydrates in our muscles and brain in the form of glycogen. When you increase the volume of your energy output, or you are recovering from a flare-up, replenishing your glycogen stores will help significantly. 

Protein is also very important as it is the structure of muscle, enzymes, hormones, and antibodies. Protein is not stored in our bodies so for it to be most effective you want to spread it throughout your day, eating it with every meal and snack. This will also help with blood sugar control, as pairing protein with carbohydrates will prevent spikes in blood sugar, which can throw off your hormone balance. Proteins are made up of 20 amino acids; 9 of these are essential, meaning you can only get them from the foods you eat. Amino acids are vital in muscle building and recovery. 

Fat is the third and final macronutrient essential for maintaining body temperature, assisting with nerve transmission, protecting and cushioning organs, promoting vitamin absorption, supporting immune function, and providing an energy source during long, low-intensity aerobic activities. Saturated and unsaturated fats are the two different types. Saturated fat intake should be kept at a minimum with the main focus on consuming unsaturated fat, as these reduce inflammation, help control cholesterol and blood pressure, and support brain health. 

Balancing caloric intake is very individualized to the person, the sport of choice, and where you are in your training cycle. Just like we all have different fingerprints, we all have different caloric needs. Starting with your RMR/BMR and then considering your activity factor. You also need to determine how to balance your macronutrient needs to optimize energy availability. To give you an idea of what this might look like- Carbs: ~5.8 gm/kg; Protein: 1.2-1.7 gm/kg; and Fat: ~1 gm/kg. (To convert your weight from lbs to kg divide by 2.2).

The most important thing to remember with fueling for your sport is to be reasonable. 

As a person who suffers from runner’s colitis, I have had to learn to listen to my body and learn from my flare-ups. Hydration is key to helping me as well as recognizing what foods I should be avoiding before a challenging workout or a race. You may have to back off the intensity for a couple of days to prevent a flare-up. Resting during a flare-up is also a good strategy to follow as you will not have as much weight loss due to an imbalance in energy expenditure. 

Always have a plan for your nutrition, just like you follow a training plan, as they go hand-in-hand.


  1. Rosenbloom, & Coleman, E. (2012). Sports nutrition : a practice manual for professionals (5th ed..). Academy of Nutrition and Dietetics.
  2. Phillips, S. M., & Van Loon, L. J. (2011). Dietary protein for athletes: from requirements to optimum adaptation. Journal of sports sciences, 29 Suppl 1, S29–S38. https://doi.org/10.1080/02640414.2011.619204 

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