Intermittent Fasting Promotes Weight Loss without Decreasing Performance in Taekwondo

Intermittent fasting (IF) is commonly used by combat sports athletes for weight loss. However, IF can decrease performance. This study aimed to investigate the effect of IF on total body mass (TBM) and Taekwondo performance. Nine athletes (seven male, two female; 18.4 ± 3.3 years) underwent 4 weeks of 12 h IF. TBM, countermovement jump (CMJ), mean kicks (MK), and total number of kicks (TNK) were compared weekly. Performance was measured in the fed state (FED) and fast state (FAST). Results showed decreased TBM in week 1 (62.20 ± 6.56 kg; p = 0.001) and week 2 (62.38 ± 6.83 kg; p = 0.022) compared to pre-intervention (63.58 ± 6.57 kg), stabilizing in week 3 (62.42 ± 6.12 kg), and no significant change in week 4 (63.36 ± 6.20 kg). CMJ performance in week 1 was lower in FED (35.26 ± 7.15 cm) than FAST (37.36 ± 6.77 cm; p = 0.003), but in week 3, FED (38.24 ± 6.45 cm) was higher than FAST (35.96 ± 5.05 cm; p = 0.047). No significant differences were found in MK and TNK in FSKTmult. RPE, KDI, and HR were similar between FED and FAST (p < 0.05). [LAC] was higher post-test compared to pre-test (p = 0.001), with higher concentrations in FED than FAST (p = 0.020). BG was higher in FED than FAST (p < 0.05) before physical tests. Therefore, IF promotes decreased TBM without decreasing performance.