Forty-eight-hour fasting declines mental flexibility but improves balance in overweight and obese older women.

• Effects of 48-h fasting were investigated in overweight and obese women. • Fasting increased subjective fatigue and perceived stress. • Fasting increased cortisol levels, but autonomic nervous system was not affected. • Fasting declined cognitive flexibility, whereas balance was improved. The purpose of this study was to investigate the effects of a 48-h fast on evoked stress, mood, and cognitive and motor functions in overweight and obese older women. Eleven women (body mass index >25 kg/m2) aged 63–80 years were tested under two randomly allocated conditions: 48-h zero-calorie diet with water provided ad libitum and 48-h usual diet. Autonomic function, cortisol levels, mood state, cognitive performance, visuomotor coordination, motor speed, and balance were evaluated before and after each diet. Fasting increased (P < 0.05) cortisol levels, whereas no changes were observed in heart rate and its variability. Fasting increased (P < 0.05) fatigue, prolonged (P < 0.05) reaction time in the two-choice reaction time test and decreased (P < 0.05) the velocity vector of the center of pressure with eyes closed, whereas no changes in performance were observed in the pursuit tracking and finger tapping tests. Thus, although a 48-h fast resulted in greater hypothalamic–pituitary–adrenal axis activity in overweight and obese older women, autonomic nervous system activity was not affected. Fasting increased fatigue and decreased mental flexibility, but improved balance. [ABSTRACT FROM AUTHOR]