Effect of 24-hour food-and-water deprivation on biochemical variables in blood.

In 38 subjects, 24-h food-and-water deprivation during the Jewish fast day, Tisha b'Av, led to a 2.5-fold increase in plasma free fatty acids and to a doubling of the bilirubin concentration. There were also significant increases in serum sodium, chloride, total proteins, albumin, uric acid, phosphorus and alkaline phosphatase and aspartate aminotransferase activity. Serum glucose and triglycerides decreased in concentration. There were no changes in concentrations of urea, potassium, cholesterol or calcium. The marked increases in free fatty acids might constitute a hazard for those with impaired myocardial function.