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Is Your Client’s Digestion Preventing Them From Getting Fitter?


Digestion is not something that gets mentioned much in articles or discussions about the importance of diet in fitness and exercise, but the personal trainer who can get their clients to optimize the efficiency of their digestive system will do them a good service that will help them achieve the results they want...


Most of us will have heard the fitness cliche: “you are what you eat”, but this statement doesn’t give due attention to digestion. It should be: “you are what you eat, absorb and don’t excrete”.

It’s great if you’re a personal trainer with a client who understands the importance of nutrition and is putting the right foods into their body to support the work you’re doing with them, but you should also try to make sure those foods are getting properly stored by their bodies.

The digestion process is supposed to break down the food we eat, transform the useful ingredients into substances the body requires and send them off to be stored, and identify the useless or toxic ingredients and send them elsewhere to be excreted.

Sometimes, for a variety of reasons, this does not happen as it’s supposed to. If the digestive system does not work properly, useless or toxic ingredients can be stored in the body instead of excreted, or useful ingredients can be allowed to pass out of the body and go to waste.

Either of these things, if it happens consistently, will certainly diminish the power of a client’s diet to help them achieve their fitness goals, whether those goals are building pounds of muscle or shedding pounds of fat.

This is why it’s very useful for a personal trainer to know how to evaluate whether or not a client’s digestive system is functioning properly.

A complete discussion of all the things that can prevent the human digestive system from working as it should do is well beyond the scope of this article. We’re only going to discuss one common problem that personal trainers can help their clients deal with - food intolerance.

Food intolerance

Let’s start by saying that food intolerances are not the same thing as food allergies.

Allergies are relatively easy to identify because the onset of symptoms is fairly rapid after ingesting something one is allergic to. The negative effects of food intolerances can take hours or days to manifest, and are often not significant enough to make a sufferer realize anything is happening.

It isn’t strictly necessary for a personal trainer to understand the main factors that cause people to be intolerant to certain foods or food groups, but they should make sure they know how to identify and treat them.

The following are common symptoms of food intolerances. If your client is experiencing these things and there appears to be no other obvious explanation, this is an indication that the client could have a food intolerance that’s compromising their digestive system:

Weight gain - Food intolerances can prevent the body from absorbing nutrients correctly, forcing it to use extra nutrients to compensate, and in turn forcing it to compensate for this by devouring extra calories, which can result in weight gain. Is your client gaining weight when they should be losing it? Or gaining weight in fat when they should be gaining it in muscle?

Breathing difficulties - Does your client ever seem to be having trouble breathing or do they suffer from asthma, hay fever or sinusitis? Food intolerance can sometimes cause or aggravate these kind of allergic airway diseases.

Fatigue - When the body has to try to digest foods it’s intolerant to, it triggers an immune system response. If this happens consistently it will tax the immune system and cause fatigue in the body. Does your client complain of feeling tired and worn out a lot despite getting enough sleep and not eating anything that would deplete the body’s energy?

Skin reactions - Does your client appear to have skin problems such as acne or eczema?

IBS - Has your client ever mentioned suffering from irritable bowel syndrome?

Breathing difficulties - Does your client ever seem to be having trouble breathing or do they suffer from asthma, hay fever or sinusitis? Food intolerance can sometimes cause or aggravate these kind of allergic airway diseases.

Headaches - Does your client get headaches or migraines quiet a lot?


Food intolerances are something that, when identified, are actually very easy to treat.

When you’ve discussed with your client the possibility that they might have a food intolerance, you should have them keep a food diary of the things they eat, and make a note of the days on which they experience any of the symptoms described above, or feel particularly lacking in energy and reluctant to work out.

This process is described in more detail in this article on food sensitivity testing.

Once you and your client feel that you’ve identified which foods or food groups they are intolerant to, the client needs to cut them out of their diet. Do this, and see if they perform any better or their body reacts more positively to their exercise regime over the coming weeks.

If you notice an improvement, then you’ve probably successfully eliminated a food intolerance that would have been interfering with your client’s digestive system and reducing the effectiveness of whatever amazingly healthy diet you’ve put them on to help them achieve their fitness goals.


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