10 Foods Runners Should Avoid

sarah cuff Food for Runners 4 Comments

As runners, there are certain foods we can choose to eat that will help us to build stronger bodies more resilient to injury and illness. There are also foods we may be better off avoiding as they tend to cause inflammation in the body and/or inhibit the recovery process, slow the healing process and block achievement of optimal body weight (let alone racing weight).

So when we are at the grocery store or settling into a restaurant for a good meal with our friends/family, what exactly should we be avoiding? Here are 10 foods you’re better off avoiding. And by avoiding, I mean not eating these foods 80-95% of the time. If a little bit slips in here or there, it’s not the end of the world – seriously, I’ve yet to meet someone that eats perfectly 100% of the time (certainly I know I’m not 100% perfect!!).

Without further adieu, the list of ‘better off to avoid most of the time’:

1. Processed sugar

I am sure you’re not surprised to see this one listed here. We know sugar is inflammatory and has been implicated for causing all sorts of chronic diseases from diabetes to cancer. It even lowers our immune system if we eat too much of it at once. Runners absolutely need to be eating enough carbohydrates to fuel our activity – but we’re better off not getting too many in the processed sugar form.

One type of processed sugar we want to especially avoid (personally I avoid it 99.9% of the time) is high-fructose corn syrup otherwise known as HFCS, and called ‘glucose-fructose’ in Canada. HFCS/glucose-fructose is metabolized differently than cane sugar and appears to activate the body’s fat storage hormone to an even larger degree than regular sugar does.

When you need to sweeten foods, reach for raw honey, pure maple syrup, medjool dates and ripe bananas. If you need something with a less distinctive taste you might reach for coconut sugar or raw cane sugar, but use even natural sweeteners in moderation of course.

2. Processed cooking oils

Most oils on store shelves and used in cooking have been highly processed (using hexane). Because they are delicate polyunsaturated or monounsaturated fats, most methods of processing render them rancid (oxidized). Processed cooking oils undergo bleaching and deodorizing to get rid of any off-putting odours and tastes. These oils cause inflammation in the body because the free radicals (which are produced when something is oxidized) damage our healthy cells. This excess inflammation delays recovery from running, among other long-term health concerns.

Avoid soy oil, corn oil, veggie oils, sunflower seed oil, canola oil, grapeseed oil and most other oils on the market that are not labeled virgin cold-pressed. The majority of these oils are also very high in omega-6 fatty acids (throwing off our omega-6 to omega-3 ratio), making them further inflammatory.

What to reach for? Choose virgin coconut oil and extra virgin olive oil, among the few good options available.

3. Margarine & shortening

Margarine and shortening are made with the aforementioned oils. Even if they do not contain trans-fats, they are still rancid/oxidized and are best off avoided.

Use real butter instead! Choose organic grass-fed butter if possible, which contains the anti-inflammatory omega-3 fatty acids. Butter also contains butyric acid, which is anti-inflammatory and promotes the growth of healthy intestinal cells.

4. Artificial sweeteners

Artificial sweeteners, such as aspartame and sucralose (Splenda), are chemical compounds – not natural foods, which is the first reason I choose to avoid them.

However, they also appear to contribute to weight gain (which obviously is exactly the opposite desired effect). I’ve seen people have a much easier time losing weight once they ditched the artificial sweeteners. Artificial sweeteners deliver the taste of sweet without the caloric content. It appears you can’t outsmart your body… Artificial sweeteners appear to disrupt the body’s ability to regulate incoming calories. Your body knows you only gave it the taste of sweet and this partial activation of the food reward pathways alters gut bacteria and triggers cravings.

5. Artificial colourings, artificial flavourings, preservatives

Some preservatives, most widely MSG, are known for being top on the list of foodstuff that causes food sensitivities and/or digestive upset or IBS. All of them are unnatural and as above, are not recognized by the body as real food.

6. Genetically engineered (GE) food

GE foods may cause inflammation in our bodies, negatively affect our immune systems and disrupt our hormonal balance – leading to all sorts of health complaints, food sensitivities due to inflamed GI systems and chronic disease not to mention delayed recovery and healing after our workouts.

When I first learned of genetically engineered food (or GMO, genetically modified organisms – meaning these foods have had specific changes introduced into their DNA), and the fact they may possible be harmful to our long-term health, I dismissed it as rubbish. I mean, how possibly could the food industry and our governments would allow something possibly so destructive to our health to flood our food system? Apparently, quite easily.

The more I learn (and experience), the more convinced I become that we are better off avoiding GE food. These foods were introduced into our food system only in the 1990’s and no long term studies have been done to show their safety (Monsanto owns the seeds and won’t allow for any long-term independent studies to be performed).

Sadly, 85-91 percent of all the soy, corn, canola, cottonseed and sugar beet crops are genetically modified. Unfortunately GE foods are not labels in Canada and most US states (even though 64 countries do label their foods, North America does not and many huge companies including Monsanto who owns all the GE seeds are fighting hard to keep it that way).

When purchasing any corn, soy or canola products, be sure to choose organic. One of the standards organic foods must meet is to be free from genetic engineering.

7. Soy protein isolate

Soy is a cheap food crop and therefore has been broken down and added to just about everything packaged and processed. Too much processed soy has been linked with flooding the body with phytoestrogens which may increase risk of some cancers. Avoid anything with soy isolates or derivatives added. Choose only organic tofu and tempeh, organic endamame, organic soy milk and organic fermented soy products such as miso and tamari, avoiding most other soy products.

8. ‘Low-fat’ foods

Most often ‘low-fat’ means sugar, flour, thickeners or salt has been added to make up for the lack of flavour, now that the flavourful fat has been removed. Obviously, sugar, flour, ‘thickeners’ and excess sodium are things to be avoided. ‘Diet foods’ by no means should be thought of as ‘healthy foods’. And although common advice is to choose low-fat dairy products, I highly recommend the opposite – choose full-fat organic yogurts and cheeses. In fact, eating butter, cream and cheese has been found to have either a beneficial effect or no effect on inflammation, while the opposite is true for low-fat dairy.

At the end of the day it appears we’re better off choosing the whole, unprocessed, full-fat food.

9. Alcohol

This one is a tough one. I go back and forth on whether it belongs on the list of things to avoid. At the end of the day, I do find that the majority of runners preform and recover better when alcohol is avoided 80-95% of the time. Certainly, if a runner is attempting to lose weight or reach their racing weight, alcohol really does need to be cut out. Similarly if a runner is injured, the alcohol tends to exacerbate the issue, delaying or even altogether preventing healing. I’ve seen a number of cases of injured athletes who simply did not heal until giving up alcohol altogether.

For those runners who are not injured and not looking to lose weight – it’s probable that one or two drinks a few times a week won’t get in the way of training (in fact studies have showed this to be the case). Personally I avoid alcohol when I’m actively engaged in a training cycle leading up to my next marathon. However, I’ll be the first to admit I absolutely celebrate with my favourite pinot grigio upon crossing the finish line!

10. Anything you have a sensitivity to

This one may be listed last but it is so very important. When we eat foods our bodies cannot digest well or react inappropriately to, we experience constant inflammation in our GI systems or a disruption of our hormonal system. Either of these unfortunate reactions can lead to systemic inflammation and cause anything from extreme fatigue and/or muscle weakness to mood swings and/or cravings to diarrhea and/or constipation, among other symptoms.

The most common foods I find to cause problems in certain individuals are dairy and gluten. In fact, I am constantly amazed at how many clients do so much better upon removing dairy (often bringing back only high quality organic cheese and yogurt is okay). Personally, I know I must avoid gluten – it causes me extreme fatigue and lethargy along with brain-fog, particularly when I’m in a high mileage training cycle.

Past dairy and gluten I’ve found soy, corn, MSG, alcohol and caffeine to be common offenders. If removing these foods still do not ease your symptoms, you might look at eggs, nuts, citrus, yeast and vinegar – and if you suffer from an inflammatory condition you might try removing nightshades (tomatoes, bell peppers, goji berries, potatoes and eggplant).

To run strong with good health is all I really ask for out of my nutrition. From personal experience I know that sometimes it doesn’t feel easy to figure out exactly what we should be choosing and what to avoid. However, I can definitely tell you once you’ve figured it out life feels SO much easier. The added benefit of running strong and healthy, achieving personal bests along the way is simply the cherry on top.

Eat clean, run strong, be well… Cheers,


Sarah J Cuff, RHN

Image 1PS. There’s nothing more inspiring than to see my clients reach new levels of success and experience a newfound love for running. When Pamela Granum first came to see me, she was suffering from extreme exhaustion following her workouts. That doesn’t make running feel like too much fun. But within a few weeks of eating 2 run, Pam’s energy levels shot up and she began having really good, strong runs! Plus, there was an added bonus she wasn’t expecting… Read Pam’s story here.

Comments 4

  1. Aspartame is mentioned in the article as a food to avoid due to it being a chemical compound, and leading to weight gain. While aspartame is a chemical compound, it is made up of 3 components found in foods you eat every day including poultry, nuts, fruits and vegetables, and is quickly broken down into these natural food components in your body before ever reaching your blood or large intestines. The myth surrounding aspartame and weight gain is also not supported by the large majority of scientific literature, and new studies are showing that diet soda (containing aspartame) can actually lead to reduced body weight and maintenance of that weight loss compared to water. So if aspartame will satisfy your sweet craving, while keeping down calories, they are great options.

    1. Post

      Hi Sweetner Council… Thank you for pointing that out – it’s true that aspartame is made up primarily of the amino acids phenylalanine and aspartic acid (as well as methanol, it’s 3rd component), all of which are found in nature… And true, unlike other artificial sweetens the body does metabolize it. This does not however render it harmless.

      The form in which these amino acids are found in aspartame is not natural. When phenylalanine and aspartic acid are consumed as free-form amino acids, as they are in aspartame, they enter the central nervous system in unusual and abnormally high concentrations which can have negative side effects (the body doesn’t know what to do with this foreign combination, therefore attempts to metabolize and excrete it).

      You mention studies now show aspartame can lead to weight loss… I’d be most appreciative if you could direct me to those links as I’d be curious to see them. I was in fact going off of these studies (and many others in fact with similar conclusions) citing weight gain from artificial sweeteners:

      – 2013, Saccharin and aspartame, compared with sucrose, induce greater weight gain in adult Wistar rats, at similar total caloric intake levels –> http://www.ncbi.nlm.nih.gov/pubmed/23088901

      – 2010 (a review of studies), While people often choose “diet” or “light” products to lose weight, research studies suggest that artificial sweeteners may contribute to weight gain –> http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892765/

      – 2008, Artificially sweetened beverage use may be fuelling (rather than fighting) long-term weight gain –> http://www.ncbi.nlm.nih.gov/pubmed/18535548

      Plus (weight loss debate aside), there are also studies (recent) such as this one that suggest aspartame may negatively affect our brain health:

      – 2014, When consuming high-aspartame diets, participants had more irritable mood, exhibited more depression, and performed worse on spatial orientation tests. –> http://www.ncbi.nlm.nih.gov/pubmed/24700203

      However, I am not necessarily an expert on artificial sweeteners – so any studies or links you have would be appreciated.

      Sincerely… Sarah

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