3 Nutrition Myths That Affect Athletic Longevity

By Susan Kleiner, PhD, RD

A long list of concepts and diet strategies target women and girls who prioritize their fitness and health. Of that long list, a few rise to the top as the most frequently cited. Which ones are myths and which ones work magic? I’ve put them head to head to find out.

Glycemic Index vs. Whole Foods

You might be surprised to learn that the Glycemic Index (GI) is a myth when it comes to a dependable health promotion strategy. While most people believe that the GI is a measure of how quickly carbohydrate (sugar) is digested and absorbed into the bloodstream, it actually does not measure that at all. The GI is a measure of the total rise in blood sugar, a value that reflects both the appearance of glucose and disappearance of glucose from the bloodstream. Speed, or rate of entry into the bloodstream has never been part of the GI measurement.

Since insulin is primarily responsible for the clearance, or disappearance of glucose from the bloodstream, a greater insulin response will clear glucose more quickly, and a less robust insulin response will clear glucose more slowly. The result is that with a rapid insulin response the total rise in blood sugar is lower, leading to a lower glycemic index value. A slower insulin response depresses glucose clearance and creates a higher total rise in blood sugar, and a higher glycemic index value.

bread-450x300Studies have shown that when the speed of entry of glucose into the bloodstream is actually measured, glucose from a specific low GI food can enter into the blood at the same speed as a specific high GI food: high fiber bread compared to white bread, for example.1,2 By the time the total glucose rise is measured, the glucose from the low GI food has already cleared from the bloodstream, whereas the high GI food has a higher GI value because glucose clearance is slower.

While this may seem difficult to ponder, the point is that our interpretation of the meaning of Glycemic Index is mythical; it has nothing to do with speed of absorption into the bloodstream, because that has never been part of the GI measurement. It has led to an extensive association with health claims that are not conclusively holding up under research investigations.

Finally, and perhaps most importantly, we are encouraged to make food purchases based on this index. Food manufacturers have adopted the index as a way of promoting their foods as healthy options. Yet the majority of foods that have GI labeling in the supermarket are processed foods that are sold in boxes. (Yes, the Grocery Manufacturers of America love the GI.) There are no GI labels in the produce aisle. There is absolutely no controversy over whether fresh fruits and vegetables, whole grains, and beans, are the healthiest choices. Whole food diets are undeniably at the top of the list of health-promoting diet strategies, helping women and girls fuel their bodies, recover from hard training, and continue to challenge themselves athletically for a lifetime.

Think outside the box! Instead of allowing the GI myth to misguide your food choices, simplify those choices by shopping on the perimeter of the supermarket or food co-op, or visiting a farmer’s market. Select the least processed fresh, or lightly processed whole foods. That’s where you find the magic!

Whole Foods vs. Sports Supplements

It’s easy to segue to this topic from the previous one. Most of you probably subscribe to the principle of eating mostly whole foods with the least amount of processing and manufacturing. When it comes to fueling your most challenging athletic endeavors and your ability to continue to challenge yourself throughout your lifetime, is this principle a myth or is it magic? The answer depends on your stomach and your training, and here’s why.

The whole food that you eat 60 to 90 minutes before your training is either still in your stomach or just making its way to your intestinal tract for absorption into your bloodstream. Your brain has been notified that your body has received food, allowing your muscles to access stored and circulating fuel to begin exercise. However, the food that’s still in your stomach and intestinal tract is not available to fuel you throughout intense exercise.

creatine-woman-drinking-from-shaker-bottle-450x340After 30 years as a sports nutritionist, I have found (and published research supports3) that the majority of people who challenge themselves athletically cannot eat the amount of food that would be needed to fuel intense exercise, and then actually train at that level comfortably. They either limit their consumption and under-fuel their training to be comfortable, or they eat enough but experience discomfort during training and cannot maximize their training sessions. Then they eat less next time. Either way, depending on whole foods to fuel intense exercise typically leads to under-fueled training.

This is a recipe for a shortened training lifespan. Each training bout, as well as supporting physical stamina for a lifetime, requires adequate fuel that supports both training and foundational health.

Intense exercise requires carbohydrate fuel.

The high fiber nature of whole foods that are rich in carbohydrate make them slow to digest and empty from the stomach. Fully fueling intense training with whole foods and being empty enough to train comfortably are often opposing goals. This is when depending on whole foods becomes a myth, and highly processed or engineered sports-specific supplements become the magic to fueling athletically challenging exercise. Pure fuel is the magical notion for supporting each exercise bout, and allowing a woman to remain strong and healthy to train hard for a lifetime.

Use whole food to feed and nourish your body. When you are performing submaximal, or low to moderate intensity exercise, you might be fine with whole food meals and snacks before exercise. When you challenge yourself with high-intensity athletic training, use the appropriate sports fuel to fully fuel your training, maximize your results and optimize that training for a lifetime. The goal is for products to rapidly empty from your stomach without causing distress, elevating blood sugar, and stimulating an insulin response. Examples are barley amylopectin (starch) and multi-transport carbohydrates (combined maltodextrin, glucose, and fructose).

"Clean" Eating vs. Recovery Nutrition

“Clean” is the most commonly used term by health-conscious consumers to describe their diets. Through surveys we know that consumers associate “clean” with food that is natural, organic, local, sustainable, fresh, safe, ethical, and healthy. The fact is that there is no legal definition to the term “clean,” and neither is there a legal definition to the terms “natural,” “local,” or “ethical.”

“Clean” and “natural” are marketing terms adopted by food manufacturers to create a whole new category of foods to manufacture, market, and sell.

Think of all the new shelf labels in the supermarket!

“Clean” as a concept has also led to food limitations and restrictions. Surveys show that many women associate a “clean” diet with no sugar, no carbohydrates, no animal protein, no dairy, no conventional farming production; all considered by these women to be healthier options to help them perform better in their lives and their fitness goals.4

PCOS-woman-eating-salad-450x300Where’s the proof? For the most part, there is none, not when it comes to cutting out whole food groups based on an unsupported concept lacking science. There may be a legitimate health condition or philosophical reasons for choosing to eliminate certain foods, but in general, this is not necessarily a healthier choice. There are certainly substantiated concepts, like limiting added sugar, choosing low or lightly processed whole foods, and partnering with local farmers dedicated to the health and welfare of their crops, their workers, and the planet.

The concept of “clean eating” as a better way to fuel an athletic female for a lifetime is a myth, and more likely than not, it is a barrier to healthy nutrition. The magic comes from the science of recovery sports nutrition, and the food choices that will best support health and athletic challenge to maximize your training, and to recover, refuel, repair and grow stronger and faster with the greatest endurance for the next training bout. That science is not about limits and restriction.

Rather than “clean eating,” the principle is to eat a combination of carbohydrates, proteins, fats, vitamins, minerals, fibers, phytochemicals, and food factors (all the things in food that we have yet to name, but that scientists recognize interact with previous factors and our cells).. The science of recovery nutrition includes all forms of macronutrients and micronutrients from foods and evidence-based supplements (such as whey and other proteins, carbohydrates, creatine, glucosamine, and fish oil) that are available, affordable, and desirable.

When participants, leaders, and role models in the female fitness industry reinforce concepts that are really artificial marketing terms without any proof, they create confusion and paralysis in consumer choice. Many women lose confidence in their knowledge of what works and what’s good for them. They have a long negative list of what they can’t eat, rather than focusing on the positive notion of what they need to eat next. They choose foods by default: anything not on the “don’t eat” list is all that’s left to eat.

Let’s embrace the magic of nutrition: the joy of breaking bread and sharing a celebration through food, the incredible satisfaction of a big recovery meal after a hard physical accomplishment, the intimacy of nourishing another human with the sustenance of a meal. Stay closer to real food and simplify your choices by turning away from the artificial marketing labels that create more distance between your diet and the choices that will best support your athletic endeavors for a long time to come.

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About the author:  Susan Kleiner, PhD, RD

Dr. Susan M. Kleiner's credentials include a PhD in Nutrition and Human Performance and an RD, FACN, CNS, FISSN certifications and honors. She is a co-founder and fellow of the International Society of Sports Nutrition and a fellow of the American College of Nutrition that honored her with a Young Investigator Award for her doctoral research. She is also a member of the American College of Sports Medicine and The National Strength and Conditioning Association. Susan is also co-founder and co-CEO of Vynna, LLC, an all female-owned, female directed, evidence-based sports nutrition brand, and author of the bestselling book, POWER EATING, as well as 6 other nutrition books. While she’s not passionately promoting healthy nutrition and fitness, Dr. Kleiner stays in a good mood by spending time in the great outdoors of the Pacific Northwest with her husband and daughters. You can learn more about her on her website and follow her on Twitter @powereat.


  1. Schenk S, et al. Am J Clin Nutr 2003; 78(suppl):742-8
  2. Eelderink C, et al. Am J Clin Nutr 2012;96:1017-24.
  3. Oliveira et al., Gastrointestinal complaints during endurance exercise: prevalence, etiology and nutritional recommendations. Sports Med. 44; Suppl 1: S79-S85, 2014
  4. Watson, E. Who is driving the clean label agenda, and has it peaked? Food Navigator-USA.com Feb. 27, 2012

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