Food myths are rampant which is no surprise with media headlines like “Coconut Oil is Pure Poison” coming shortly after “Is Coconut Oil a Superfood?” Media sources sell catchy headlines that don’t capture the entire story and use research articles that are not generalizable to the population resulting in conflicting and confusing dietary advice. Runners looking to maximize their diet and performance are especially susceptible to this misinformation. So lets put an evidence-based stop to a few nutrition myths, once and for all.
Low-Carbohydrate Diet is Best
This myth has been around for a long time. Starting with Atkins diet in the early 2000s and now rebranded as Paleo, Keto, and Whole 30. This myth perpetuates despite the fact that researchers have not been able to prove that a low-carbohydrate diet is any more effective for weight loss than a low-fat diet (1).
Low-carbohydrate diets also don’t take into consideration nutrient density. Both a small slurpee and a cup of chickpeas contain approximately 45g of carbohydrates. Both foods are restricted on a low carbohydrate diet despite the fact that chickpeas also contain fibre, protein, iron, and calcium. Removing complex carbohydrates such as whole grains, fruit, and legumes from the diet reduces dietary fibre and valuable vitamins and minerals. A series of systematic reviews published in The Lancet showed that higher intake of dietary fibre and whole grains is associated with less risk of cardiovascular disease, diabetes, and colorectal cancer (4). Not to mention that carbohydrates provide satisfaction and enjoyment, an important dietary component that is often forgotten when following any diet.
As for runners, I’d hold off before you go on a low-carb diet. Carbohydrates are the primary fuel source for muscles. And while it is possible to adapt to fat burning through a ketogenic diet, there have been no advantageous benefits to athletes doing so. In fact, a very-low-carbohydrate diet reduces the ability to perform high-intensity work such as hills or sprints to a finish line (2,3).
2. You Should Never Eat Past 7 pm
This anecdote is so widespread and stated as fact that no one ever stops to ask, is this true? There is one study that is widely cited in online weight loss articles that showed a decrease in weight from participants who didn’t eat past 7 pm vs the control group that did (5). However, this study had only 29 male participants and lasted only 2 weeks, hardly proof that an entire population should follow a 7 pm cut off time. So with limited evidence to support this claim, why is it thought of as absolute truth? Because one woman in the early 2000s proclaimed it true on T.V., Oprah Winfrey. With Oprah’s seal of approval, this myth has been passed between friends, family members, and colleagues for over a decade.
The problem with picking a time on the clock to dictate when to stop eating is that it doesn’t consider nuances in schedules. How does the rule doesn’t fit shift workers, night owls, people who exercise at 8 pm or mom’s up multiple hours per night breastfeeding their child? Additionally, having any diet rule in place sets up a dichotomy of rule following vs not rule following (IE good vs bad), which can lead to feelings of shame and guilt if a rule is not followed. A broken rule leads to “what the heck” eating where you eat regardless of fullness and satisfaction knowing that tomorrow the rule will be back in place.
So break free of your 7 pm rule and focus inward. Are you hungry after 7 pm? Then eat. Are you eating for other reasons - emotions, boredom, or routine? Then it’s time to focus on mindful eating strategies and ensuring you have additional coping skills outside of food.
3. Some Sugars are Healthier Than Others
Peruse Pinterest for healthy homemade baking and you’ll find a number of recipes with a “sugar-free” claim only to find they substitute white sugar with honey, maple syrup, or coconut sugar. But wait, aren’t those still sugar? The answer is yes. However, some types of sugars have a health halo around them making you believe they are healthier than the typical white table sugar.
Table sugar is sucrose - a type of sugar that is 50% glucose and 50% fructose. Other sugars - honey, maple syrup, coconut sugar, etc. are the same components but in slightly different proportions. The varying levels of glucose and fructose can alter the level of sweetness and glycemic index (a measurement of how much a food/drink raises blood sugar levels). However, the differences in glycemic index are minimal and would only make an impact if consuming large quantities of sugar.
Many also believe that honey or maple syrup is healthier because they contain iron, zinc, and B vitamins but again, in order to receive any quantifiable amount of these nutrients, you would need to eat large quantities. Choosing a balanced diet would be a better option to get your vitamins and minerals than honey and syrup.
Ultimately, it’s best to aim for less added sugar in your diet. If you put less honey into a recipe than sugar because of its increased sweetness, that is a healthy swap but don’t fool yourself into believing your recipe is sugar-free or filled with vitamins and minerals. That’s simply a myth.
1. Johnston, B., Kanters, S., Bandayrel, K. et al. (2014)Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults A Meta-analysis. JAMA, 312(9),923-933.
2. Urbain, P., Strom, L., Morawski, L., Wehrle, A., Deibert, P., & Bertz, H. (2017). Impact of a 6-week non-energy-restricted ketogenic diet on physical fitness, body composition and biochemical parameters in healthy adults. Nutrition & metabolism, 14, 17.
3. Zajac, A., Poprzecki, S., Maszczyk, A., Czuba, M., Michalczyk, M., & Zydek, G. (2014). The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists. Nutrients, 6(7), 2493-508.
4. Mann, A., Cummings, J., Winter, N., Mete, E., Morenga, L. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 393(10170), 384-386. British Journal of Nutrition, 110, 2108-2113