Yes. As far as I can recall, the issue is your intracellular levels of these electrolytes and essential minerals might be depleted (at the expense of maintaining adequate blood concentrations during fasting). So when you start eating, a rapid rise in insulin will signal cells to go into storage and growth mode, which will rapidly draw electrolytes from your blood and into tissues. This can leave you with dangerously low or unbalanced blood electrolyte levels even if they appear normal before ending the fast. Better to be safe than sorry!