People with eating disorders take such concerns to extremes, developing abnormal eating habits that threaten their well-being and even their lives. This question-and-answer fact sheet explains how psychotherapy can help people recover from these dangerous disorders.
The interest on balance in your PPF account is compounded annually and is credited at the end of the year. But the point to remember is that the interest calculation is done every month: the interest is calculated on lowest balances in account between 5th and the last day of the month.
Suppose the rule is that they are compounding and crediting you interest on the 1st of the following month, based on ending balance of the prior month. Maybe you can only save the money for 3 months, and then you have to draw the account down to $1 on the 31st of the last month.