Gut health has been a hot topic in recent media – and for good reason! While diet culture often distorts the conversation, understanding how proper fueling supports gut health can be a game-changer, especially for athletes and active individuals. In my work with clients, I often see GI issues as one of the first underfueling symptoms. When my clients understand how their GI system works, they’re better equipped to identify what’s causing their symptoms – and how to fix it.
That’s why I teach the 5 ‘F’ Factors of Fueling to stay fed and avoid the RED: Factory Belt, Flow, Feeling, Fiber, and Feeding.
5 Key Fueling Factors to Prevent Underfueling and RED-S in Athletes
#1: Factory Belt
Digestion begins at the smell, sight, thought, and/or ingestion of food. This stimulates our factory belt to start slowly moving from the beginning of the belt to the end (mouth to anus).
The speed of the factory belt depends on:
- Food composition (carbohydrates, fats, proteins, fiber).
- Time since your last meal or snack.
- How fast you consume your meals.
- Additional factors.
When this system slows down, it contributes to common underfueling symptoms like bloating or constipation.
#2: Flow
After food is broken apart in the stomach, it is then absorbed in the intestines by villi, which contain digestive enzymes that break food into absorbable nutrients. For example, villi contain lactase which helps break down lactose.
Villi can become stressed and flattened out due to:
- Underfueling.
- Dehydration.
- Lack of sleep.
- Alcohol use.
- Unmanaged day to day stress.
This flattening may result in malabsorption and lead to bloating, diarrhea, constipation, reflux, etc.
If you experience sudden food intolerances, they may be due to an inflammatory reaction and NOT an immune reaction.
Not all stress is inherently bad. For example, training results in a desired adaptation, as long as it is accompanied by proper rest and nourishment.
#3: Feeling
You may have heard our gut (GI system) referred to as our second brain. That is because our gut is in constant communication with our brain through the vagus nerve. The vagus nerve is the grand communicator acting like a traffic light between our gut, heart, lung, and brain.
(What happens in vagus does NOT stay in vagus).
The vagus nerve communicates signals to the brain that tell us when it is time to eat and when we have consumed enough food for this eating period.
If we constantly ignore the signals coming in, our brain becomes trained to ignore them too, resulting in a disconnected body.
#4: Fiber
While fiber, fluids, and focusing on protein are important, in excess they can lead to a “fake” fullness. Fiber and fluids take up space in our gut while providing little to no calories. Fiber and protein slow digestion and increase satiety. Because of these factors, too much fiber, fluids, and focus on protein can make it harder to meet our calorie and carbohydrate needs.
Too much of a good thing can be a bad thing, and excess fiber, especially if you have an already slow GI motility, may add unnecessary strain and make digestion even harder.
We don’t need food to take up space and not pay rent (provide energy).
#5: Feeding
Grazing throughout the day (whether to avoid the feeling of fullness, perceived fatigue from a larger meal, GI issues during training, or due to lack of time) typically results in inadequate energy intake at the end of the day. Continually turning on the factory belt (grazing) may lead us to miss signals of hunger & fullness. (Think… only ever filling up ¼ of your gas tank).
This can confuse our interconnected GI system that uses sensations and nutrients to promote satiety and may contribute to GI issues such as reflux, bloating, and bacterial overgrowth.
Adequate meals with time in between allows our digestive system to rest and digest.
Ready to Stay Fed and Avoid the RED?
Understanding and applying these 5 ‘F’ Factors – Factory Belt, Flow, Feeling, Fiber, and Feeding – can help you optimize digestion, prevent underfueling symptoms, and avoid RED-S as an athlete.
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