Why loss is debit?

In the double-entry bookkeeping system, Income items are credits and Expense items are debits. Therefore, if you have a loss, your expenses are more than your income resulting in a debit balance. A loss, of course, reduces the book value of the company, reflected in the Equity section of the Balance Sheet. Equity normally has a credit balance. So, to reduce Equity, a debit entry reflecting the loss must be made.