Using the LOWFODMAP Diet leading up to Race week: Could this be the newest tool to add to your arsenal?

The low FODMAP diet has recently become one of the most widely searched diets in performance nutrition. This is because the low FODMAP diet can help athletes reduce stomach discomforts such as runner’s gut symptoms and help improve performance outcomes. It is a diet containing small amounts of fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are types of carbohydrates, commonly found in foods such as fruit and veg, breads and pasta and milk and dairy products. These foods form a large part of most people’s diet, however, if low FODMAP foods can be eaten instead of these foods, you can fuel your body to be competition ready.

In this blog post I’ll be taking you through the pros and cons of the low FODMAP diet. I’ll explain why you may benefit from it, what foods you can enjoy while on the low FODMAP diet and how you can make simple changes to your diet to help improve your performance.

My goal for you after reading this blog post will be to have a greater understanding of the low FODMAP diet. The focus is not about what foods you must remove from your diet, but how you can change your eating patterns to benefit most on race day. I will breakdown the science behind the diet and explain whether you need to alter your diet to achieve your performance goals hassle free.

 Why follow the low FODMAP diet approaching race week?

The importance of training for endurance events is never questioned, yet the importance of nutrition is often underappreciated, or only comes to mind close to race week. This is when many uncertainties around nutrition for training pop up and may lead to extra anxiety in your preparation for race week. In this nutrition guide we will explain what the low FODMAP diet is and how to best fuel for the week leading up to endurance events, using the low FODMAP diet. We will also talk about what foods you should avoid and how to implement the low FODMAP diet leading up to races to avoid gastrointestinal (GI) upset and help optimise your performance on race day.

So, what is the low FODMAP diet? The low FODMAP diet has been commonly used for the management of irritable bowel syndrome (IBS) but is becoming increasingly popular within endurance athletes for the management of GI symptoms, which can impact performance. It is a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs). These are types of short chain carbohydrates found in common foods such as fruit and vegetables, dairy products and foods made from wheat such as bread and pasta. It has been found that these foods are commonly consumed by endurance athletes, in large amounts, prior to and during endurance events. We all know that a bowl of pasta is a quick and handy meal that will fuel a race, but have you ever experienced GI discomfort from eating pasta before a race? Or who hasn’t eaten a banana before or during an endurance event? I most certainly find it a handy snack before games. However, these foods are considered high FODMAP foods and have been associated with GI issues and deficits in performance in athletes during endurance events.

Here is a list of common high FODMAP foods and low FODMAP food alternatives:

(MONASH-fodmap)

Sources of FODMAPs, how they are absorbed in the body and how these lead to GI symptoms.

Fructose

The main FODMAPs present in fruit and vegetables are fructose and fructans. Fructose, the natural sugar in fruit, is absorbed in the small intestines by carrier proteins which transport fructose across the cell membrane by a process called diffusion. In fructose sensitive individuals a limited supply of carrier proteins causes fructose to be malabsorbed.

Lactose

Lactose is the naturally occurring sugar in dairy and the main FODMAP in dairy products which is mainly found in soft cheeses, milk and yoghurt. Hard cheeses are naturally low in lactose and can be included in the low FODMAP diet. Lactose malabsorption occurs when there is a lack of the enzyme lactase needed to breakdown lactose into smaller molecules, glucose and galalactose. It is important to say that if you are excluding dairy products from your diet, it is vital to check that the dairy alternatives you choose are fortified with calcium to ensure you are not lacking in this nutrient.

Oligosaccharides

Galacto-oligosaccharides (GOS) are found in nuts, legumes and pulses. GOS are particularly high in red kidney beans, split peas and baked beans, as well as falafels which contain a combination of high FODMAP foods. Oligosaccharides have been reported to be poorly absorbed and result in becoming fermented by bacteria in the gut.

Polyols

Polyols are sugar alcohols and include sorbitol and xylitol which are commonly used as sweeteners in foods. These include artificially sweetened drinks, confectionary and sugar free chewing gum products. You should look out for these ingredients on the back of food packets. As a rule of thumb, if you can’t pronounce or don’t recognise the ingredient then it probably isn’t good for your gut! Large polyol molecules are thought to be absorbed poorly across the intestines and may lead to adverse GI symptoms.

When FODMAPs are poorly absorbed in the body they become fermented by bacteria in the gut and can cause GI symptoms such as bloating, diarrhoea, fluid retention, flatulence and discomfort. For these reasons FODMAPs may be excluded from the diets of people experiencing GI discomfort and be gradually reintroduced over time to help identify what foods are causing the triggers to their symptoms.

Low FODMAP and athletes

It has been shown that up to 50% of athletes report GI issues as the main cause of underperformance in endurance events. Recent studies have shown that athletes who exercise excessively or undergo endurance events may be more prone to gut issues and this has been termed ‘exercise-induced gastrointestinal syndrome’. This can lead to health consequences such as malabsorption of nutrients and nutritional deficiencies if gut cells become damaged. Endurance events lasting 2 or more hours seems to be the cut-off point where significant GI issues occur, irrespective of an individual’s fitness level. The low FODMAP diet is applicable to endurance athletes because they commonly report high FODMAP foods as part of their pre-race nutrition strategies, including tailor made sports nutrition products such as energy drinks and gels. With that being said, GI symptoms are not only caused by dietary intake but are transient, multifactorial and are specific to everyone. However, it has been found that GI symptoms are commonly the limiting factor in endurance exercise. So, if you can relate with GI symptoms negatively affecting your performance, following a low FODMAP diet in the 7 days leading up to an endurance event may help reduce GI issues like cramping, bloating and pain during exercise. This is because there is a reduced fermentable carbohydrate load in the body. However, the pros and cons of the low FODMAP diet should be weighed up by you first.

Pros of the low FODMAP diet for endurance athletes:

• Reduced GI symptoms related to exercise.
• Increases in perceived endurance capacity and intensity.
• Improvements in performance outcomes.

Cons of the low FODMAP diet for endurance athletes:

• The restrictive nature of the low FODMAP diet may be hard for athletes who want to continue training during this period if calories and other nutrients are not sufficiently replaced in the diet.
• Changing your usual food intake may take time to adjust to.
• Increased burden on you to prepare your own food and snacks as readymade foods are typically high in FODMAPs.
• Further studies are needed to examine the effects of the low FODMAP diet in athletes in the long term.

Take home messages

So, when and how should you implement the low FODMAP diet?

1. Try the low FODMAP diet if you have attempted all other options and GI symptoms still persist
2. Implement the low FODMAP diet with the help of a registered nutritionist
3. Keep a food dairy to determine the exact FODMAPs which are triggering the GI issues
4. Plan an elimination and reintroduction phase for each FODMAP
5. Only eliminate FODMAPs which cause GI upset as maintaining a full low FODMAP diet in the long term can be very restrictive. 

I would just like to thank you for checking us out and having a look at our blog. This is the first edition from our newest team member Michelle.

And please do remember that we are here to help you in any way we can so don’t be shy and get in touch with any of your questions, Id be more than happy to help you.

Don’t forget to download our E-book on Carbohydrate periodisation, where I will take you through the key concepts of how to match your carb intake to your training intensity.

Grab the eBook

Here are the main areas that I cover in this eBook that can help you take control and push your performance to the next level.

1. How to fuel training sessions based on intensity (high/low)
2. 6 key ways to pull off training low 
3. 3 ways to optimise training high 
4. The 3 most important variables to take into account 

References

Wiffin, M., Smith, L., Antonio, J. et al. Effect of a short-term low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet on exercise-related gastrointestinal symptoms. J Int Soc Sports Nutr 16, 1 (2019).

Killian LA, Muir JG, Barrett JS, Burd NA and Lee S-Y (2021) High Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAP) Consumption Among Endurance Athletes and Relationship to Gastrointestinal Symptoms. Front. Nutr. 8:637160.

Costa RJS, Snipe RMJ, Kitic CM, Gibson PR. Systematic review: exercise-induced gastrointestinal syndrome-implications for health and intestinal disease. Aliment Pharmacol Ther. 2017 Aug;46(3):246-265.