GCC study challenges conventional sports nutrition wisdom

Research conducted at Grove City College could upend decades of conventional wisdom within the sport nutrition field and provide athletes with a better understanding of the importance of diet not only on performance but also health.

Department of Exercise Science faculty Dr. Philip Prins and Dr. Jeffrey Buxton recently published a study of the impact of low and high carbohydrate diets on athletic performance that indicates the traditional plate of pasta before a game may not have any impact in their performance and could negatively impact the health of some who consume this diet.

“High carbohydrate, low fat diets have been the predominant eating strategy for athletes for performance, but recent evidence from our lab has challenged the superiority of that eating approach over low carbohydrate, high fat diets,” Dr. Philip Prins

The study looked at how a group of middle-aged runners and triathletes performed in high intensity exercise under both high carbohydrate, low fat and low carb, high fat diets. Subjects followed the diets for 31 days and were evaluated throughout on their performance, the body's ability to utilize carbohydrates and fat for fuel, heart and metabolic risk factors, and blood sugar levels.

“Our study found similar high-intensity exercise performance, as well as similar fasting insulin, high-sensitivity C-reactive protein, hemoglobin A1c – all markers of heart and metabolic health – and record rates of fat oxidation, which demonstrates the body – once fat adapted – is using a large amount of fat for fuel even at high exercise intensities, which disproves the notion that fat is an inferior metabolic fuel unable to support high intensity exercise, which has been the traditional thought,” Prins said.

He said subjects on the low carb/high fat diet also showed elevated levels of LDL, and HDL cholesterol, which are markers of heart health, and reduced and stable blood sugar levels compared to the high carb/low fat diet.

“The results from the current investigation in addition to previous work from our lab challenge whether higher carbohydrate intake is superior for athletic performance and demonstrate that lower carbohydrate intake may be a therapeutic strategy to improve blood glucose control, particularly in those at risk for diabetes,” Prins said. “We found 30% of lean, well-trained fit athletes participating in our trial had interstitial glucose values consistent with pre-diabetes when eating standard high-carb athletic diet. That was completely resolved on the low carb diet.”

The study “disproves” a century-old belief that high intensity exercise can’t be sustained from fat oxidation, according to Dr. Timothy Noakes, professor at Cape Peninsula University of Technology, South Africa, and a co-author of the paper. “This is perhaps the single most important scientific paper that I've been privileged to be associated with in 40-plus years of scientific research,” Noakes said.

The study “Low and High Carbohydrate Isocaloric Diets on Performance, Fat Oxidation, Glucose and Cardiometabolic Health in Middle Age Males” was published in Frontiers in Nutrition, a leading journal of the nutrition scene. In addition to Prins, Buxton, Noakes, co-authors include Jeff Volek and Alex Buga of The Ohio State University, Dominic D’Agostino of University of South Florida, and Dr. Andrew Koutnik of Florida Institute for Human and Machine Cognition.

The study was conducted in the College’s Exercise Science Human Performance Laboratory with the six students helping with data collection. They include current students junior Kelli Jancay of Mars, Pa., junior Anna Jenkins of Forest, Va., junior Holly Grose of Kailua, Hawaii; recent graduates Dalton Jones ’22 and Naomi Tobias ’22; and Kara Heckman, who served as registered dietician for the study.

The research was completed with the support of The Swezey Scientific Instrumentation and Research Fund, which helps Grove City College’s Hopeman School of Science, Engineering and Mathematics fund student and faculty research. Since its inception in 2007, the fund has been used to support a wide range of scholarly work, purchase research equipment and provide research stipends to students.

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