Poster Topical Area: Sports Nutrition
Poster Board Number: 242
Objective: Despite escalating attention to high-fat, low-carbohydrate, ketogenic diets (KDs), they have not been thoroughly evaluated in exercising persons. Therefore, the purpose of the present investigation was to evaluate the effects of a KD on body composition using an advanced, 5-component (5C) model and performance using an array of exercise tests spanning the phosphagen, anaerobic, and aerobic energy systems. Design: A longitudinal, diet- and exercise-controlled investigation was conducted in recreationally-trained men and women consuming either a KD (percent energy as carbohydrate:fat:protein, 5:72:23) or an isocaloric carbohydrate-based control diet (CD; 53:24:23) during 9-weeks of supervised cardiovascular (2 days per week) and resistance (3 days per week) exercise. 5C fat mass (FM), lean soft tissue (LST), and protein were calculated using physician's scale-determined body weight, DXA-determined bone mineral content and FM, and bioelectric impedance-determined body water content. Performance was assessed using 1-repetition-maximum (1RM) tests for the back squat and bench press, vertical jump, a 6-set Wingate sprint protocol, and a 5km time trial. Measurements were completed pre- and post-intervention.
Results: A differential effect on body weight (p=0.031) was observed for the KD (-1.1 kg) versus CD (+0.3 kg), and this was associated with a trend (p=0.075) for greater loss of FM (KD: -3.2; CD: -1.9 kg). The KD reduced (p=0.017) extracellular fluid (KD: -0.3; CD: +0.3 L), yet increases in LST were identical between groups (+2.1 kg). Estimates of body protein did not differ (p=0.328) between groups (KD: +1.2; CD: +0.9 kg). No differences (p> 0.05) were observed for squat (KD: +10.5; CD: +12.0 kg) or bench press (KD: +5.4; CD: +5.6 kg) 1RM, nor were differences (p=0.715) found for the 5km time trial (KD: -2.23; CD: -2.56 minutes). The KD tended to reduce (p=0.054) peak power output during the first Wingate (KD: -28.1; CD: +25.1 W). However, recovery of peak power generation between the first and final set was greater (p=0.042) in the KD group (+155.9 W) than the CD group (+70.0 W).
Conclusions: A KD may be used by active persons for improvements in fatigue resistance to high-intensity exercise without compromising other domains of athletic ability or body composition.
Texas Woman's University