Effect of 8 days of water-only fasting and exercise on liver, kidney and pancreas functions in middle-aged men.

Fasting and physical exercise significantly modify the functioning of the body's internal organs. The aim of the study was to investigate the simultaneous effect of an 8 days of water-only fast and physical exercise on selected functions of the liver, kidneys and pancreas in middle-aged men. The following parameters were determined in the serum and blood of 18 men before and after 8 days of water-only fasting: aspartate aminotransferase (AST), alanine aminotransferase (ALT), uric acid (UA), total protein (TP), albumin (AL), amylase (AY), ferritin (FR), cortisol (C), β-hydroxybutyric acid (β-HB), hematocrit (Ht) and lactate (LA) under conditions of rest and physical exercise. The daily volume of urine excreted, its specific gravity and the concentration of C and AL in it were also determined. Additionally, the De Ritis index, and AL/CR ratio in urine were calculated. The fasting intervention significantly increased the activity of liver enzymes, the concentration of UA, FR, C, β-HB (p < 0.01) as well as the specific gravity of urine (p < 0.05). On the other hand, it decreased AY activity in serum (p < 0.01) and the daily amount of urine excreted (p < 0.05). Physical exercise increased the concentration of TP, AL (p < 0.01) and LA (p < 0.001). Despite many significant changes determining the function of the liver, kidneys and pancreas, no negative health effects caused by either factor were found. The recorded changes only herald potential adverse health effects that may occur if the impact of fasting and/or physical exercise intensifies.