"Keto" Diet in Taekwando Athletes: Good for Performance, Less Beneficial for Body Composition - Non-Sign. Higher Muscle & Lower Fat Loss in 25% Deficit vs. Balanced Diet

Ketogenic dieting will help to preserve performance, but in contrast to what the hype on the Internet says, it won't help already lean taekwondo athletes to improve their body composition.

Only recently Volek et al. have published an article in the European Journal of Sport Science discussing role as "fat as a fuel for endurance exercise" in which they highlight that ketones do not simply provide "a stable source of fuel for the brain", but may also "act as a signalling molecule capable of altering gene expression [...] that could extend human physical and mental performance beyond current expectation" (Volek. 2014).

If you look at the outcomes of a recent study from the Jungwon University and the Seoul Women’s University in Korea it would appear as if Volek, Noakes and Phinney were actually up to something.

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The purpose of said study was to investigate the effects of the weight loss through 3 weeks of ketogenic diet on performance-related physical fitness and inflammatory cytokines in Taekwondo athletes.

Figure 1: Macronutrient composition of the two 25% energy reduced test diets (Rhyu. 2014)

"The subjects selected for this research were 20 Taekwondo athletes of the high schools who participated in a summer camp training program. The subjects were randomly assigned to 2 groups, 10 subjects to each group: the ketogenic diet (KD) group and the non-ketogenic diet (NKD) group. Body composition, performance-related physical fitness factors (2,000 m sprint, Wingate test, grip force, back muscle strength, sit-up, 100 m sprint, standing broad jump, single leg standing) and cytokines (Iinterleukin-6, Interferon-γ, tumor necrosis factor-α) were analyzed before and after 3 weeks of ketogenic diet." (Rhyu. 2014)

In contrast to what you'd expect based on the hype around ketogenic dieting in the bodybuilding and fitness community,  the ketogenic diet that contained 55.0%, 40.7%, and 4.3% of the daily energy intake in form of fat, protein and carbohydrates respectively did not experience greater improvements in body composition than their peers on a 30%, 30%, and 40% fat, protein, carbohydrate diet.

If you want to do a keto diet, say goodbuy to tons of protein: What may not be obvious to all of you is the fact that the diet at hand is low in carbs, but not high enough in fat to be truly ketogenic. With 40% protein you are not going to go into ketosis. That's simply too much protein to be converted to glucose in the liver - specifically if you get some of the protein from fast digesting protein sources like whey, which will spike the blood amino acid levels and kickstart hepatic gluconeogenesis. Unfortunately, the study does not list the absolute protein intake, but if we assume a baseline intake of 2800kcal per day for the subjects, they would have consumed 210g of protein per day - that's 3.2g/kg for these lean guys - and still lost muscle.

What is particularly interesting in this context is that the diet is as Jacob Wilson pointed out in a comment on my facebook page, probably not even "ketogenic". As he says, they found in their studies that "subjects generally need to have fat near 70 % or above to reach nutritional ketosis". The diet in the study at hand is thus too high in protein - just like the diets of 90%+ of the people in the fitness world who believe they were following a ketogenic diet, when they are in fact only eating a high protein diet with some fat and low carbohydrates in it.

Figure 2: Effects of ketogenic vs. non-ketogenic diet w/ 25% reduced energy intake on body composition (left) and performance marker, i.e. 2,000m sprint times and wingate peak & mean power, as well as anaerobic fatique during wingate test (Rhyu. 2014)

Rather than at an advantage, the athletes on the keto diet appear to be at a visible, albeit statistically non-significant disadvantage, when it comes to the effects of the -25% calorie-reduced diet on their lean and fat mass. Against that background it is all the more surprising that the scientists found significant decreases in 2,000 m sprint time in the ketogenic diet group that were not present in the non-ketogenic dieters. In addition, the "high carbers" felt significantly more fatigue after a standardized Wingate test and had higher levels of tumor necrosis factor-α - an indicator of increased inflammation compared to the "no-carb" keto-genic diet.

The surprising data from a 2011 study by Mendes-Netto et al. shows that an almost fat-free diet yields leaner gains than a low(ish) fat diet | learn more.

Bottom line: Overall, the results of the study at hand suggests that ketogenic diets can have significant performance conserving effects in taekwondo athletes and others who have to cut weight periodically.

The commonly heard claim that ketogenic dieting would lead to significantly more beneficial improvements in body composition in dieting athletes, on the other hand, is clearly falsified by the results of the study at hand. If anything, the loss of muscle mass is more and the loss of fat mass less pronounced than it would be with a balanced medium-to-high carbohydrate diet | Comment on Facebook.

References:

• Rhyu, Hyun-seung, and Su-Youn Cho. "The effect of weight loss by ketogenic diet on the body composition, performance-related physical fitness factors and cytokines of Taekwondo athletes." Journal of Exercise Rehabilitation 10.5 (2014): 326-331.
• Volek, Jeff S., Timothy Noakes, and Stephen D. Phinney. "Rethinking fat as a fuel for endurance exercise." European journal of sport science ahead-of-print (2014): 1-8.