Nutrition [ Food News & Facts]

Research: Low-Carb Diets and High-Performance Athletes

by Alexandra Williams, MA

Whether you call it keto, Paleo, Atkins®, training low or something else, low-carb eating continues to be popular in the mainstream. But what are the implications for athletic performance in the gym or on the field?

A panel of sports nutrition experts met to discuss macronutrient needs for physical activity, with the results published in Nutrition Today (2018; 53 [1], 35–39). Author Mitch Kanter, who holds PhDs in physiology and nutrition, reported: “One factor that remains as true today as it did decades ago is the athlete’s indispensable need for carbohydrate,” as it is “the substrate most efficiently metabolized by the body and the only macronutrient that can be broken down rapidly enough to provide energy during periods of high-intensity exercise.”

Still, the experts expressed concern that many athletes—especially those who regularly exercise strenuously—aren’t getting enough carbohydrates. Convened by the Alliance for Potato Research and Education, the panelists noted that research suggests physically active people can adapt to a ketone-promoting diet, but they emphasized that staying with this kind of diet long-term is potentially detrimental. Concerns included

  • athletic performance decrements;
  • impairments to cognitive performance, focus and mood;
  • increased perception of fatigue; and
  • a greater susceptibility to skeletal muscle damage.

The “training low” concept was deemed “potentially more faddish than practical,” especially because it leads to reductions in training intensity. Panelists were strong in their assertions that low-carbohydrate stores make it difficult to sustain the intensity levels at which most competitive and serious recreational athletes perform.


So how can fitness professionals successfully respond to clients who ask about low-carb diets? Nancy Clark, MS, RD, CSSD, a sports dietitian in the Boston area and author of Nancy Clark’s Sports Nutrition Guidebook (2013), has some input.

“Many sports-active people try to stay away from carbs, fearing they are fattening or addictive. Not the case. Carbohydrates are not fattening. Excess calories of any type are fattening,” she says. The key word here is “excess.” “When people get too hungry, they crave carbohydrate for quick energy, and they can easily overeat bread, cookies, pasta and so on,” Clark says. “The problem is not those ‘addictive’ carbs. The true problem is [allowing yourself to get] too hungry.”

Ultimately, Clark echoes the panelists’ sentiments: “The body preferentially burns carbohydrate. For optimal [athletic] performance, the foundation of each sports meal should be grain-based foods, starchy vegetables and fruits.”

Myth: Plant Foods Are Not Sources of Complete Proteins

You may already know that nine of the 22 essential amino acids—the building blocks of protein—cannot be produced by the body. A “complete” protein source is a food that contains all nine of these.

It’s particularly important for people cutting back on animal products to understand plant proteins and ensure that all of the essential amino acids are included in the diet. Amanda Boyer, MS, RDN, CD, NASM-CPT, owner and nutrition therapist at Wholehearted Nutrition (, has some helpful information. “Plant-based foods that are high-quality [complete] sources of protein include quinoa, buckwheat and soy, which includes edamame and tofu,” she says.

However, incomplete plant proteins—such as grains, nuts, beans and legumes—can be consumed with complementary plant proteins to create a complete protein source. For example, pair a whole-grain food with nuts, nut butter, beans, legumes or vegetables, says Boyer. She offers these delicious duos: peanut butter on whole-grain bread; a burrito bowl with black beans and brown rice; and a whole-grain wrap with spinach, tomato, onions, cucumber and avocado.

Boyer notes affordability as a side benefit to swapping in some plant proteins. Plant-based sources of protein also provide nutrients not found in animal foods, such as fiber and some antioxidants. “Both animal and plant proteins can serve different and wonderful purposes in a person’s diet,” she concludes. “It doesn’t have to be an all-or-nothing experience. It really comes down to a person’s preferences, abilities in the kitchen and unique belief system as to how they approach food.”

Alcohol: Is One a Day Still Okay?

Is moderation still the key when it comes to alcohol consumption? No, according to a comprehensive study published in The Lancet.

Denouncing previous reports promoting the protective effects of occasional alcohol consumption, the worldwide study calls for global medical guidance to be revised. The researchers do acknowledge that moderate drinking may protect against heart disease and diabetes; however, they say the risks of cancer and other illnesses outweigh perceived benefits. This is contrary to national guidelines that suggest drinking one or two glasses of beer or wine per day is generally safe for women and men, respectively. “The widely held view of the health benefits of alcohol needs revising,” according to the report.

The study reviewed levels of alcohol use and their health effects on people aged 15–95, in 195 countries, between 1990 and 2016. Its findings: Alcohol led to 2.8 million deaths in 2016 and was the leading risk factor for premature mortality and disability among people aged 15–49, accounting for 10% of all deaths.

The study, which has 120 co-authors, concluded that the level of alcohol consumption that minimizes harm across health outcomes is “zero . . . standard drinks per week.” The decline in life expectancy for a 40-year-old who drinks between 100 and 200 g weekly is 6 months, on average, compared with someone who drinks between 0 and 100 g, according to the study. Drinking 200–350 g of alcohol per week is linked with a 1- to 2-year decline in life expectancy, while imbibing more than 350 g aligns with a 4- to 5-year average life expectancy drop.

The American Council on Science and Health is challenging the results, stating that among other flaws, the study didn’t adjust for confounders. It remains to be seen whether or not the United States and other countries will modify their alcohol consumption guidelines.

Feeling Good About Omega-3s

A recent pilot study published in the Journal of the American College of Cardiology has shown a link between a higher omega-3 index and lessened symptoms of depression in people who suffer chronic heart failure (CHF) and major depressive disorder (2018; 6 [10], 833–43). The goal of the research was to test the “effects of long-chain omega-3 fatty acid supplementation on omega-3 levels, depressive symptoms and other psychosocial factors,” as well as other CHF-related measures.

A relatively small cohort of 108 people with both CHF and major depressive disorder were put into groups taking a daily 2-gram dose of one of three oils: EPA (eicosapentaenoic acid), an EPA/DHA (docosahexaenoic acid) combo, or corn oil (as a placebo). EPA and DHA are types of omega-3 fatty acids found in fatty layers of shellfish and cold-water fish, plant and nut oils, walnuts, flaxseed, and fortified foods

After 12 weeks, the EPA/DHA group showed significant improvement in depressive symptoms and social function. With about 6.5 million adults now living with chronic heart failure, and 16 million adults in America experiencing a major depressive episode in 2016 alone, this pilot study is a welcome precursor to further studies.

Weight and the Workplace

Baby showers, birthday bashes, company lunches, breakroom snacks . . . What effect do these have on the waistlines of American workers? Recently, scientists from the Centers for Disease Control and Prevention sought to answer that question.

By examining data from the weeklong USDA Food Acquisition and Purchasing Survey, presenting author Stephen J. Onufrak, PhD, and colleagues noted that 22% of the more than 5,200 people in the cohort had obtained food or beverages at work at least once a week. Though most of these snacks were monetary freebies, they “cost” the employees an average of nearly 1,300 calories per person per week. Further, the choices themselves left much to be desired, nutritionally speaking: Workplace selections were typically high in empty calories, sodium, refined grains, hydrogenated fat and added sugars. Interestingly, demographics influenced the choice to dig in, with white, female and college-educated employees the most likely to partake.

In a press release provided by Nutrition 2018, the annual meeting of the American Society for Nutrition, Onufrak suggested that employers may want to create “healthy meeting policies” to “encourage healthy food options at meetings and social events.” He added, “Worksite wellness programs . . . have been shown to be effective at changing health behaviors among employees. We hope that the results of our research will help increase healthy food options at worksites in the United States.”

Fitness professionals can improve that possibility: If you administer exercise programming in a workplace, consider sharing this article with your corporate contacts. (You can also find a helpful PDF called “Tips for Offering Healthier Options and Physical Activity at Workplace Meetings and Events” on Other fit pros may simply want to share this calorie wake-up call with clients so they won’t “counteract” their workout during the workday.

Live Longer: Don’t Go Too Low-Carb

Recent research from the Medical University of Lodz, Poland, noted that long-term adherence to a low-carb diet could actually shorten one’s lifespan (European Society of Cardiology 2018). In an analysis of nearly 25,000 people from the National Health and Nutrition Examination Survey, a research team led by Professor Maciej Banach found that those who consumed the least amount of carbs were 32% more likely to die prematurely from any cause, with even higher risk differentials in death from heart disease, stroke and cancer. If a client’s workout goal is a longer, healthier life, following a low-carb program may run counter to that aspiration.

5 Reasons to Grab Easy-Open Pistachios


These popular tree nuts have numerous health benefits, and they’re lower in calories and fat than other nuts, according to a literature review published in Nutrition Today (2016; 51 [3], 133–38). Here are just a few things this beautiful nut can do for your body:

Researchers at Loma Linda University Health in California discovered that regularly eating nuts improves brain waves, as measured with an EEG. Pistachios created the greatest gamma wave response, associated with learning, processing, retention and other key cognitive functions (FASEB Journal 2017; 31 [1], Suppl.).

Data from two randomized, controlled, crossover feeding studies showed that both pistachios and almonds could increase the number of potentially beneficial microbiota in the gut—but the effect of pistachios was “much stronger” (British Journal of Nutrition 2014; 111 [12], pp. 2146–52).

The Nutrition Today summary mentioned above also reported that pistachio intake seems to be inversely related to an increased risk of type 2 diabetes. Pregnant women in particular should pay attention to this: A study in PLOS One reported that adding even more extra-virgin olive oil and pistachios to a Mediterranean diet reduced the risk of gestational diabetes (2017; 12 [10], e0185873).

A study in Nutrition Journal reported that eating a snack combo of tree nuts (like pistachios) and dried fruit (like raisins) could improve blood sugar control and lower the risk of diabetes and/or cardiovascular disease (2016; 15 [23]).

5. INHIBIT CANCER CELLS In 2017, scientists at the Institute of Nutrition at Friedrich Schiller University in Germany found that both raw and roasted pistachios inhibited the growth of colon cancer cells while bolstering chemopreventive effects (Nutrients 2017; 9 [12], 1368).

Tempting Ways to Use Pistachios

Ready to “get crackin’” and incorporate pistachios into your everyday meal plan? You don’t always have to eat them by hand. The American Pistachio Growers offer plenty of ideas on their website ( for how to put more pistachios on your plate. Here are a few to pique your culinary curiosity:

  • sprinkled on top of a rice or açai bowl
  • mixed with avocado for pistachio molé
  • ground into flour
  • baked into focaccia bread (shown, left)
  • puréed into a green-tea smoothie
  • rolled into no-bake date balls

Find recipes for these and other pistachio dishes at

Meet our experts

AFM_Author_Williams Alexandra Williams, MA, A writer and editor, as well as a lecturer at UC Santa Barbara in the department of Exercise Studies, Sport and Recreation. She is a vegetarian who cooks and bakes from scratch. Find her at

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