Is your Food Intolerance Inhibiting your Fitness?


Author: Jennifer May

Do you find yourself tiring more quickly than your used to? Do you feel breathless, bruise easily, struggle with long recovery times?

Do you experience generalised fatigue and reduced motivation for exercise? Do you find it difficult to get results from your training program despite following a very healthy diet?

If the answer is yes to any of the above, you may be suffering from a food intolerance. Food intolerances are becoming increasingly common and yet often are undiagnosed or mismanaged.

While for some food intolerance can feel like nothing more than embarrassing gas after a pizza, for others the symptoms can be severe, systemic and debilitating.

What is a food intolerance?

A food intolerance or sensitivity is your body reacting negatively to a food causing symptoms of ill health. Intolerance typically results from a combination of poor gut health, intestinal permeability (leaky gut) and an imbalanced immune system. This combination of conditions allows large food molecules to be released into the blood. Your immune system then responds by releasing immunoglobulin G (IgG).

IgG forms an immune complex with a substance called complement, traps the invader (in this instance the food protein) by binding to various tissues around the body and neutralise/destroy it. Whilst this is an immune response designed to help protect you, in the instance of food intolerance this is an unnecessary and chronic response to a frequently consumed substance which can cause wide-spread damage to tissues such as the muscles, digestive system and more.

How could food intolerance affect your fitness?

Now you have a better understanding of the physiology of food intolerance, let’s discuss the how and why this condition may affect your fitness…

Nutritional deficiencies

The lining of the gut wall is an active filter system. Nutrients do not simply slip across the lining; they are actively absorbed – meaning there are several necessary steps of this process which happens within the lining of a healthy digestive system.

With food intolerance nutrient absorption is reduced. Ineffective daily absorption over time leads to nutritional deficiencies.

Many nutrients, such as Vitamin C, Zinc and Glutamine are essential for tissue repair and enzyme production. So, here’s the paradox: as levels of these valuable nutrients decline, we lose the ability to digest foods, absorb nutrients and heal the digestive system (or any other damaged tissues).

Poor muscle growth and slow recovery from exercise

In addition to the muscle breakdown from the IgG response, the overactive immune system coupled with nutritional deficiencies can have a significant impact on muscle growth, recovery and overall fitness.

Each time you perform a new exercise, or push yourself past your usual limit, you are stimulating muscle breakdown. The immune system then responds by sending out neutrophils and macrophages to eat the damaged tissue. You’ll then relay more capable, more specific muscle tissue which is better at that particular activity. This is how we get stronger, fitter and of course is how we build bigger muscles.

To make neutrophils and macrophages we need Zinc. To regulate the immune response, we need many nutrients including vitamin A, vitamin D and vitamin C. To re-build muscle tissue we need zinc, glutamine, protein, vitamin C, iron and many more nutrients. Deficiency of any of these nutrients as seen in food intolerance may lead to earlier fatigue, slower recovery time, poor ability to build muscle and lower level of fitness.

Dizziness, fatigue and lactic acid build up

Iron is a difficult mineral to absorb even in a healthy digestive system. Iron is responsible for the production of red blood cells – which carry oxygen around the body. Lower levels of iron lead to small red blood cells called microcytes which are poor oxygen transporters. This leads to early fatigue, quicker lactic acid build up and a longer recovery time. Some of the fittest people may begin feeling breathless when walking up a small flight of stairs whilst iron deficient. Iron deficiency, as seen in food intolerance can lead to weakness, fatigue, dizziness, anxiety, depression and poor sleep. Symptoms include all of the above plus easy bruising, frequent yawning and poor memory.

Poor cellular energy production

Nutrients such as iron, magnesium and B Vitamins are crucial for the production of cellular energy. Inside each cell of the body (particularly muscle cells) there are little batteries called mitochondria.

Inside the mitochondria we convert carbs, fats and proteins from food into energy through processes called the Krebs cycle and Electron Transport Chain (ETC). These processes require several nutrients for their function. Put simply, we cannot convert food into energy without the assistance of nutrients such as iron, magnesium, B Vitamins, Lipoic acid, Carnitine and many more. Deficiency of these nutrients, common in food intolerance, will lead to us feeling fatigued, unfit and slow.

I hope this article has been helpful and informative. These are just some of the many ways that food intolerance can inhibit your fitness, reduce strength and inhibit muscle building. If you or someone you know are currently experiencing difficulties with your fitness progression despite following a healthy diet and exercise program, it may be time to explore your options for food intolerance assessment. Feel free to reach out if you require any assistance – my team would love to help you.


Jennifer May is a Nutritionist, Author and Health speaker in Sydney Australia. Jennifer is the Director of Food Intolerance Australia and Sydney City Nutritionist where she works directly with patients and with large organisations to support their corporate wellbeing initiatives.

In her spare time, Jennifer also mentors students and new graduates of Nutrition and Dietetics.

Follow Jennifer and her team to get more information like this on her social media pages and or buy her book Pure Health & Happiness.