Why calorie based norm is not adequate to identify the poor?

Why calorie based norm is not adequate to identify the poor?

The government uses Monthly Per Capita Expenditure (MPCE) as proxy for income of
household to identify the poor. Poverty line is estimated by the monetary value (per capita expenditure) of the minimum calorie intake that was estimated at 2400 calories for a rural person and 2100 for a person in the urban area. But this calorie based norm is not adequate to identify the poor, due to following reasons
The minimum calories required for the children below 1 year are 300 and for adults who
perform heavy work minimum caloiy intake is 3600.