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Tuesday, 11 June 2019 16:05

The Athlete's Kitchen: Sports Nutrition Myths: Busted!

Written by Nancy Clark MS RD CSSD
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Keeping up with the latest science-based sports nutrition recommendations is a challenge. Runners are constantly bombarded with media messages touting the next miracle sports food or supplement that will enhance athletic performance, promote fat loss, build muscle, and help you be a super-athlete. At this year's Annual Meeting of the American College of Sports Medicine (www.acsm.org), a sports nutrition myth-busters session sponsored by Professionals In Nutrition for Exercise and Sport (www.PINESNutrition.org; a global network of sports dietitians) featured experts who addressed the myths that commonly confuse runners and all athletes.

MYTH: Protein supplements build bigger muscles.
Protein needs for a 150-pound (68 kg) runner average about 110 to 150 grams of protein per day. (More precisely, 0.7 to 1.0 g pro/lb. body weight/day; 1.6 to 2.2 g pro/kg./day) Hungry runners can easily consume this amount from standard meals. Yet, many runners believe they need extra protein. They consume protein shakes and bars in addition to protein-laden meals. They are unlikely to see any additional benefits from this higher-than-needed protein intake. Resistance exercise is a far more potent way to increase muscle size and strength than any protein supplement. Plus, your muscles need three times more carbohydrate than protein to be adequately fueled.

MYTH: Eating just before bedtime causes a runner to "get fat."  
While it is true the body responds differently to the same meal eaten at 9:00 a.m., 5:00 pm, or 1:00 a.m., a runner will not "get fat" by eating at night. The main problem with nighttime eating relates to the ease of over-eating while lounging around and watching TV. When your brain is tired from having made endless decisions all day, you can easily decide to eat more food than required.
     That said, bedtime carbohydrates to refuel depleted muscles and bedtime protein to build and repair muscles can optimize recovery after a day of hard training or competing. For runners who want to optimize muscle growth, eating about 40 grams of protein before bed provides an extended flow of amino acids needed to build muscle. (This bedtime snack has not been linked with fat gain). Cottage cheese, anyone?

MYTH: A gluten-free diet cures runners' gut problems.  
If you have celiac disease (as verified by blood tests), your gut will indeed feel better if you avoid wheat and other gluten-containing foods. However, very few gut issues for non-celiac runners are related to gluten. FODMAPs (Fermentable Oligo-, Di-, Mono-saccharides and Polyols) are often the culprit. These are types of hard-for-some-people-to-digest carbohydrates found in commonly eaten foods such as wheat, apples, onion, garlic, and milk. For example, the di-saccharide lactose (a kind of sugar found in milk) causes gut turmoil in people who are lactose intolerant. The poorly digested and absorbed lactose creates gas, bloat and diarrhea.
     For runners who live in fear of undesired pit stops, a low FODMAP diet two or three days before a competition or long training session can help curb intestinal distress. Your sports dietitian can help you learn more about a short-term FODMAP reduction diet.

MYTH: Runners should avoid caffeine because of its diuretic effect
With caffeinated beverages, the diuretic effect might be 1.2 ml. excess fluid lost per mg. of caffeine. That means, if you were to drink a small mug  (7 oz./200 ml.) of coffee that contains 125 milligrams of caffeine, you might lose about 150 ml. water through excess urine loss. But you'd still have 50 ml. fluid to hydrate your body—and likely more if you drink coffee regularly. Runners who regularly consume caffeine habituate and experience less of a diuretic effect. In general, most caffeinated beverages contribute to a positive fluid balance; avoiding them on the basis of their caffeine content is not justified.

MYTH: Athletes should be wary of creatine because it is bad for kidneys.
Creatine is sometimes used by athletes who want to bulk up. It allows muscles to recover faster from, let's say, lifting weights, so the athlete can do more reps and gain strength. A review of 21 studies that assessed kidney function with creatine doses ranging from 2 to 30 grams a day for up to five and a half years indicates creatine is safe for young healthy athletes as well as for elderly people. Even the most recent studies using sophisticated methods to assess renal function support creatine supplements as being well tolerated and not related to kidney dysfunction.

MYTH: The vegan diet fails to support optimal performance in athletes.
Without a doubt, vegan athletes can —and do—excel in sport. Just Google vegan athletes; you'll find an impressive list that includes Olympians and professional athletes from many sports (including not only running but also football, basketball, tennis, rowing, snow boarding, soccer, plus more.)
    The key to consuming an effective vegan sports diet is to include adequate leucine, the essential amino acid that triggers muscles to grow. The richest sources of leucine are found in animal foods, such as eggs, dairy, fish, and meats. If you swap animal proteins for plant proteins, you reduce your leucine intake by about 50%. For runners, consuming 2.5 grams of leucine every 3 to 4 hours during the day optimizes muscular development. This means vegan runners need to eat adequate nuts, soy foods, lentils, beans and other plant proteins regularly at every meal and snack.
     Most runners can consume adequate leucine, but some don't because they skip meals and fail to plan a balanced vegan menu. Vegan runners who are restricting food intake to lose undesired body fat need to be particularly vigilant to consume an effective sports diet. Plan ahead!


Nancy Clark, MS, RD counsels both casual and competitive athletes at her office in Newton, MA (617-795-1875). The newest 6th edition of her best selling Sports Nutrition Guidebook is being released in July 2019. For information about readymade handouts and PowerPoint presentations, visit www.NancyClarkRD.com. For her popular online workshop, see www.NutritionSportsExerciseCEUs.com.

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