Today Debbie talks to Dina Griffin again about how an athlete wants to approach their diet during training and in the off-season. She also talks about the difference between ketosis and just having a controlled carbohydrate intake. In her opinion, many people don’t have to go the more extreme route of ketosis, but rather, they can control the amount and types of carbs that they are consuming to enhance their training.
Debbie wonders what a person’s plates will look like for eating throughout the seasons. In winter, Dina recommends a half a plate between high-quality proteins and fats, and the other half non-starchy vegetables. An athlete can start adding carbs in the form of starchy veggies or whole grains during the spring. However, this only applies to training days, so days where you have a short workout, you can stick with the half and half model. In the summer, you might ramp up the carbs a little more, but Dina makes the point that all of this is dependent on individual responses, types of training and the types of athletic goals that you have as well. So while she is providing some general rules, she’s aware that there may be many exceptions.
She also makes the point that our concept of metabolic efficiency for athletes is certainly fat burning, but it doesn’t require that we engage in ketosis. An article came out recently about athletic diet, but her critique of this study is that it only recognizes a high-carb approach and ketosis. She is recommending a controlled carbohydrate approach, which is neither. Her response to the review follows:
Research Article Review
by eNRG performance Sport Dietitians Dina Griffin and Becca Rick
As Sport Dietitians, we assume responsibility for staying up-to-date on current research in an effort to educate ourselves and our clients. Used in conjunction with what we see to work in practice with our athletes and clients, research helps to guide the nutrition recommendations we provide. As such, it is critical that we analyze research by digging into the fine details that aren’t necessarily provided in an abstract or in line with the message that is ultimately passed along to consumers.
A recently published review article in The Journal of Sports Medicine entitled ‘Carbohydrate Dependence During Prolonged, Intense Endurance Exercise’ by Hawley and Leckey (link here) caught our attention and inspired us to provide our community with an analysis. The main points of the review article include:
Competitive endurance athletes freely select carbohydrate-rich diets
The volumes and intensities at which endurance athletes train are highly dependent on carbohydrate-based fuels, particularly events lasting up to 3 hours
High-fat, low-carbohydrate diets do not improve training capacity or performance
When reading through the details of the review paper and considering how the main points are summarized, there are a numerous considerations we noted:
High-fat, low-carbohydrate (HFLC) diets are defined as 20 grams of carbohydrate (or less) per day. This level of carbohydrate may not be necessary to achieve nutritional ketosis. It is also significantly lower than what most endurance athletes need in order to achieve a metabolically efficient nutrition plan. Much of the argument related to HFLC nutrition uses these dietary extremes, while not acknowledging there is a more moderate approach which can yield both health and performance benefits for endurance athletes.
The article continues to make claims that HFLC diets do not have a sparing effect on glycogen storage, yet this same article clearly states that a HFLC diet does have a sparing effect (even following a period of fat-adaptation, carbohydrate restoration). The article also states that HFLC diets have a direct negative impact on athletic performance by down-regulating pyruvate dehydrogenase (PDH) levels, an enzyme involved in carbohydrate oxidation. While basic biochemistry explains enzyme down-regulation, there are no reference studies or data provided to demonstrate a performance detriment. In the end, it seems to leave the reader confused.
Rating of Perceived Effort (RPE) is often collected in dietary studies and assumed to be higher during exercise for individuals on HFLC diets. In this article, mention of a 4-day study comparing a high-fat diet with a high-carbohydrate diet in cyclists found RPE to be significantly higher in the high-fat group. First, we expect any major dietary change to require an adaptation period, which typically requires more than 4 days. Secondly, we must also remember that RPE is very subjective and not always a reliable marker, especially when used between groups.
The review states that athletes naturally select diets rich in carbohydrate (CHO), but this is a tough claim to make. The evidence cited for this is nearly 15 years old. Additionally, we must also consider the promotion of high-CHO dietary patterns by many nutritionists and sport dietitians, in addition to the influence of the food industry at large. High-CHO foods are also widely available and generally more affordable than sources of proteins and fats.
Throughout the review article, there is no acknowledgment of the influence of daily nutrition patterns upon metabolic adaptations, nor the observed and expected influence that training has on these adaptations. Through years of our data collection, we have clear evidence showing daily nutrition patterns greatly influence substrate use at rest and during exercise.
We must point out the conflict of interest from Gatorade Sports Science Institute and their relationship with Dr. Hawley. While GSSI has funded important research to further our understanding of sports nutrition in many ways, we still must acknowledge their monetary interest in the continuation of promoting high-carbohydrate diets for the athletic population.
While the authors recognize the importance of nutrition periodization, their conclusions are to continue promotion of high carbohydrate availability before and during competitions for endurance athletes. Nutrition Periodization strategies absolutely should be employed for athletes, yet part of a periodized plan can also include Metabolic Efficiency Training to utilize dietary and exercise strategies that enhance the body’s ability to utilize a greater proportion of endogenous fat stores. As mentioned above, there is not a need to implement very low carbohydrate diets in order to yield various health and athletic benefits. Perhaps as the body of research grows, review articles like this will better acknowledge this viable alternative to fueling the endurance athlete. However, it is also clear that we must be mindful of where nutrition messages arise as some can be heavily influenced by the sports nutrition industry.
These are just a few of our compiled thoughts on this latest review article. Look for future blog posts exploring more research perspectives related to the growing field of fat oxidation research and its application for health and athletic performance.
Dina earned her master’s degree in Food Science and Human Nutrition from Colorado State University and is a Board Certified Specialist in Sport Dietetics and a Certified Level II Metabolic Efficiency Training Specialist. She is a competitive half marathon and marathon runner, age group triathlete, and ultrarunner earning top placement and age group wins in several races.
She is a sport nutritionist at eNRGperfomance.com. For more information about metabolic efficiency go to metabolicefficiency.org.