There’s little that will sully a ride quicker—or simply mess with the enjoyment of everyday life—than stomach woes.
If you’ve struggled with diarrhea, gas, or bloating a little internet detective work may have brought to light the low FODMAP diet, a type of elimination diet that is hailed as a way to suss out what may be causing your gastrointestinal problems.
The diet has caught on among an increasing number of athletes as a way to finally help stomach troubles that are negatively affecting training and race performance. So we dug into the nuances of this eating plan to see if it is truly the happy GI diet.
All About the Low FODMAP diet and Its Potential Benefits
The acronym FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, thus a low FODMAP diet is a way of eating that limits or restricts foods that contain these types of short-chain carbohydrates. For example, fruits that are high in FODMAPs contain higher levels of polyols—which put the “P” in FODMAP. Some foods including wheat-based pasta and onions are high in fructans—one of the oligosaccharides, and the “O” in the acronym. Disaccharides include lactose present in various dairy products.
“The mechanisms of how FODMAPs can cause GI issues are not fully understood,” says Kathryn Adel, MS, RDN, CSSD, LD, owner of Fitwave Nutrition in Charleston, South Carolina. But Adel, who specializes in addressing GI problems in athletes, explains that FODMAPs are not completely digested or absorbed in our intestines and instead are fermented by gut bacteria in the large intestine producing gas as a result. This can cause the intestinal wall to stretch and expand and in people with a highly sensitive gut result in symptoms, including stomach pain.
Adel tells Bicycling that people with irritable bowel syndrome (IBS), or other digestive diseases such as Crohn’s disease, are the most likely to experience symptoms when exposed to FODMAPs, but for many people this type of food doesn’t bother them at all.
For individuals who typically only have symptoms when they exercise, Adel says there are a couple of mechanisms at play. “When we start exercising, there is increased stimulation of the sympathetic nervous system, which reduces gastric emptying and intestinal motility. This can impair the transport of nutrients and lead to the malabsorption of FODMAPs which are harder to digest.”
She adds that simultaneously, the blood flow moves into the muscles to provide them with oxygen and nutrients. “Therefore, there is less oxygen available along the gastrointestinal tract, which creates damage and inflammation to the gut.”
Digestive upset such as gas, bloating, and diarrhea can ensue, none of which is conducive to a brag-worthy ride. “Following a low FODMAP diet before and during exercise can sometimes help reduce symptoms,” notes Adel.
The point of the low-FODMAP diet is to weed out foods that contain these types of carbs— and there are a lot of them. Following a period of low-FODMAP living, foods are slowly reintroduced to see what’s the most problematic.
It’s important to understand that the low-FODMAP diet is not designed to be a weight-loss plan or one that picks on a particular macronutrient. Instead, it’s designed to determine what foods trigger GI symptoms, and create an eating plan to reduce or eliminate those symptoms.
Also, while there is some overlap between a low FODMAP diet and a gluten-free diet, they’re not one in the same. That said, Adel says many gluten-free grains like quinoa, rice, and buckwheat tend to be lower in oligosaccharides so therefore, may work better for some people with GI distress.
Foods That Contain FODMAPs
Foods that are high in FODMAPs, meaning ones that may cause GI symptoms in some people, include:
- Dairy (milk, yogurt, ice cream, soft cheeses)
- Wheat-based foods, including cereal, bread, and crackers, and relatives of wheat including barley, rye and farro
- Beans and lentils
- Certain vegetables, including artichokes, asparagus, beets, cauliflower, Brussels sprouts, peas, onions, mushrooms and garlic
- Certain fruits, including apples, ripe bananas, cherries, pears, grapefruit, mango, peaches, and most dried fruit
- Honey, agave, and high fructose corn syrup
- Sorbitol, mannitol, xylitol
- Cashews and pistachios
The Monash University FODMAP Diet App provides a large list of which foods are low, moderate and high in FODMAPs. It’s worth noting that Adel explains that sourdough bread, even when made with wheat, is low FODMAP because the fermentation process reduces its fructan content.
As for the gels, bars, and sports drinks that so many riders count on to help them keep pushing the pace, Adel cautions that some are low FODMAP and some are not. “It is important to verify the ingredient list.”
For example, if your product of choice is made with honey, fructose, or corn syrup it will deliver a dose of monosaccharides that could upset sensitive GI tracts. Ditto for the sugar alcohols like xylitol found in some products that are a source of polyols.
A report in the journal Frontiers in Nutrition found that athletes typically consume high FODMAP foods during prerace dinners and breakfasts and more frequent sports nutrition product use was often related to increased frequency of GI symptoms—perhaps because many of the items the participants were using during exercise were high in FODMAPs.
How to Know if You Should Try the Low FODMAP Diet
If you’ve been experiencing long-term digestive issues on and/or off the bike it could be worth exploring a low FODMAP diet to try to pinpoint trigger foods. “Whether you try this diet depends on several factors including the timing of the digestive issues, if there are some red flags like unexplained weight loss and blood in stools, and what other dietary changes have been made,” says Adel. “It could be a good idea to consult with a gastroenterologist and/or a registered dietitian who specializes in gut health to rule out more severe issues and determine if the low FODMAP diet is appropriate.”
Irritable bowel syndrome, or IBS, is a common gastrointestinal disorder, affecting about 10% to 15% of Americans, according to the American College of Gastroenterology. An expanding body of research suggests that following a low-FODMAP diet may help alleviate several of the objectionable symptoms of IBS, like bloating and gas.
For example, a study in the American Journal of Clinical Nutrition published in 2022 found that people with IBS experienced fewer GI problems when placed on a low FODMAP diet, but eliminating gluten had no benefit. However, there was a fair amount of individual variability in how effective the diet was in reducing symptoms, meaning it works for some people with IBS but not all.
What is less clear is whether avoiding FODMAPs can improve gastro health and result in fewer trips to the bathroom for people without a diagnosed GI condition like IBS. This includes cyclists who frequently struggle with stomach distress during rides.
A small study of 16 individuals published in the Journal of the International Society of Sports Nutrition showed that cutting out specific FODMAP-containing foods for a week alleviated the exercise-related gastrointestinal issues including cramps and bloating in 69% of people who experience these when they work out, and improved a person’s perceived ability to exercise.
The study authors speculated that this outcome is likely explained by a reduction in intestinal water volume and gas production, caused by fewer indigestible carbohydrates available for fermentation in the gut. But this investigation was conducted on runners who can be more susceptible to GI symptoms during exercise than cyclists. Further studies are needed to examine the benefits of this diet in athletes participating in various sports when combined with various fueling strategies.
In reality, Adel says midride stomach issues often has more to do with fueling methods than being sensitive to any FODMAPs. “Dehydration is a huge factor, which can include not drinking enough fluid, but also not getting enough electrolytes, especially sodium.”
Not training your gut to better tolerate a high intake of carbs during activity can also spur on gastro woes and urgent bathroom breaks. Adel stresses that it is important to trial different foods and sports products (gels, bars, drinks, etc.) during training to find the ones that work for you. And perhaps look at what you are eating before hopping on the saddle. Too much fiber, fat, or protein can slow digestion leading to GI symptoms that are similar to being sensitive to FODMAPs.
You should always be aware that cutting out FODMAP foods can become restrictive—it requires limiting foods like traditional pasta and fruits like apples that many cyclists rely on for their daily fuel. But making simple swaps, like an orange instead of that apple, can make the diet more approachable.
Some research does suggest that low FODMAP dieters may fall short in a handful of key nutrients including fiber, iron, calcium, and vitamin C that overtime can impact health and performance. Adel adds that it’s important for athletes following a low FODMAP diet to make sure they are still meeting their calorie, carbohydrate, and micronutrient needs. “If you are using numerous FODMAP-containing foods to fuel up on and off the bike you need to find appropriate alternatives,” she says.
Some initial research also suggests a diet that strictly eliminates FODMAPs has a potentially unfavorable impact on the gut microbiota, and could potentially lead to nutrient deficiencies and disordered eating. But more research is needed.
How to Follow a Low FODMAP Diet
To be clear, the low FODMAP diet isn’t meant to be a long-term solution. It’s designed to help you figure out what leads to your uncomfortable stomach symptoms, so you can cut back on only those foods, not whole food groups.
The low FODMAP diet can be considered an elimination diet, and there are three phases to it. Adel explains that you start by cutting out high-FODMAP foods for two to six weeks to allow your gut time to respond to the different eating pattern. “It is not recommended to stay on a low FODMAP diet beyond this time,” she adds.
During this elimination phase, you may start to notice some improvement in your GI symptoms. Because it can be tricky to navigate on your own, working with a registered dietitian can help you design a plan that limits FODMAPs while making sure you’re still getting the nutrients you need to be healthy and support training.
Here is a sample meal plan that would provide a low-FODMAP diet:
- Breakfast: Cooked oatmeal with strawberries and almonds, and a hard-boiled egg
- Lunch: Grilled chicken quinoa salad with spinach, cucumber, and bell pepper
- Snack: Lactose-free yogurt topped with sunflower seeds and blueberries
- Dinner: Baked salmon with brown rice, and sautéed kale with olive oil
After the initial two- to six-week period, you’ll start to slowly re-introduce those foods back into your diet. “There is a specific protocol to follow which consists on using foods that represent FODMAP family and trial them in increasing amounts over three days,” says Adel. You may discover that certain high-FODMAP foods give you issues, while others don’t. Remember, this includes any on-bike fuel you want to consume while training.
It’s important to log your symptoms as you re-introduce foods, to help pinpoint problem items. If you re-introduce more than one FODMAP group at a time and experience symptoms, it will be a challenge to figure out which food(s) caused the problem.
Finally, you’ll work on maintaining the right diet if any changes are required. This means steering clear of your triggers and instead focusing on the healthy foods and sports nutrition products that don’t aggravate your issues.
If you’re on a low-FODMAP diet for about two weeks and it is not helping you, Adel stresses there’s no reason to be on it indefinitely and you should stop following it and talk to you doctor or a registered dietitian to figure out next steps.
The Bottom Line on the Low FODMAP Diet
This diet can certainly help some people—especially those with IBS—identify their trigger foods and offer a line of defense against digestive issues. And it can still be nutritious if appropriate food substitutions are made. But it’s not a dieting decision to take lightly.
The low-FODMAP is too restrictive and challenging to follow to try to make it your first choice for battling run-of-the-mill GI issues. You should only turn to it when you’ve exhausted other options, like eating enough fiber, hydrating properly, and perhaps training your gut for long rides.