Women should not train in a fasted state because their energy tolerance threshold is higher than that of men. Training on an empty stomach triggers a strong secretion of stress hormones in women and blocks muscle recovery signals, whereas men tolerate this fasted effort well.

noli's read

This advice is based on real physiological concepts but applies them too absolutely. The concept of minimal 'energy availability' is well-supported by expert consensus from the International Olympic Committee on RED-S (Relative Energy Deficiency in Sport), which confirms that women possess a higher metabolic sensitivity than men in cases of energy deficiency. Observational studies also indicate that fasted training increases cortisol secretion, which can temporarily hinder protein synthesis. However, stating that women can never train in a fasted state is an exaggeration. Literature reviews and short-term clinical trials show that endurance sessions of less than 60 minutes at moderate intensity are generally well-tolerated without negative hormonal impact, provided that the total daily energy intake is sufficient. Finally, the idea that men tolerate fasting during exercise perfectly is nuanced by randomized controlled trials showing that a prolonged deficit also disrupts their own hormonal balance.

the sources

1. 1Hackett D, Hagstrom AD 2017
2. 2Vieira AF, Costa RR, Macedo RCO, Coconcelli L, Kruel LFM 2016