The effect of weight loss by ketogenic diet on the body composition, performance-related physical fitness factors and cytokines of Taekwondo athletes

Abstract

The purpose of this 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. 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 3weeks of ketogenic diet. No difference between the KD and NKD groups in weight, %body fat, BMI and fat free mass. However, the KD group, compared to the NKD group, finished 2,000 m sprint in less time after weight loss, and also felt less fatigue as measured by the Wingate test and showed less increase in tumor necrosis factor-α. This result suggests that KD diet can be helpful for weight category athletes, such as Taekwondo athletes, by improving aerobic capacity and fatigue resistance capacity, and also by exerting positive effect on inflammatory response.

Effect of carbohydrate restriction on oxidative stress response to high‐intensity resistance exercise

“…Thus, additional human trials are needed. Three weeks of a KD in humans has been shown to reduce OS resulting from caloric restriction and exercise as previously found in Taekwondo athletes . Rhyu and Cho also reported attenuated elevations in TNF‐α during a weight loss program associated with a KD; though, these data are not entirely comparable since a change in body mass and/or body composition likely effects circulating cytokine levels.…”

“…Three weeks of a KD in humans has been shown to reduce OS resulting from caloric restriction and exercise as previously found in Taekwondo athletes. 25 Rhyu and Cho also reported attenuated elevations in TNF-α during a weight loss program associated with a KD 25 ; though, these data are not entirely comparable since a change in body mass and/or body composition likely effects circulating cytokine levels. Further, 14 days of a KD has also been shown to increase blood antioxidant status in active, healthy women in response to a caloric restricted intervention.…”

Affective and Enjoyment Responses to Short-Term High-Intensity Interval Training with Low-Carbohydrate Diet in Overweight Young Women

“…Given that LCs dramatically restrict the energy intake from carbohydrate, which could accelerate the exhaustion of glycogen content to provide energy during exercise, high-intensity exercise performance during LCs may be particularly impaired Nutrients 2020, 12, 442 3 of 13 as carbohydrate is the dominant energy source [31,32]. Additionally, some studies revealed that metabolic adaption to ketosis resulting from LCs may exert positive influences on maintaining or even improving exercise performance [33,34], because a more durable energy source was obtained through the enhanced fat-utilization ability [32] that can help in sparing the limited glycogen storage [35]. Supposedly, an acute bout of HIIT under LC conditions could be more demanding for overweight individuals to perform, and thus they may perceive HIIT to be less enjoyable than an acute bout of MICT under LC conditions since the body still relies heavily on carbohydrate to generate energy.…”

Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance?

“…A cross-over study revealed that after 4 weeks of a LCHF diet, body weight and fat mass were significantly decreased in well-trained offroad cyclists (Zajac et al, 2014). Consuming a hypocaloric LCHF or HCLF diet for 3 weeks resulted in similar decreases in body weight and fat mass in high school taekwondo athletes (Rhyu and Cho, 2014). …”

“…In another study, combining a LCHF diet for 3 weeks with a 25% energy restriction resulted in the loss in lean body mass and impairment in anaerobic performance measured by the Wingate test in high school taekwondo athletes (Rhyu and Cho, 2014). It is noteworthy that performance requiring greater endurance capacity such as a 2000 m sprint, and a fatigue index in the Wingate test were actually increased in the LCHF group.…”