Food Ratio Concept:

'The  Engel coefficient, derived from the Engel curve (see MEC-001: Microeconomic Analysis),  proposes that  the  ratio of  food to non-food expenditure could  serve as a useful welfare indicator. Studies have shown that households with  higher levels of income usually spend  a  smaller  fraction  of their total  income  on food  while  the reverse applies  to households with  lower incomes. It is also noted  that the  ratio of food  to  non-food  expenditure increases with  family  size. This approach, however, needs  to  be  qualified  by  the  findings that the poorest households  in  developing countries do not necessarily spend a higher fraction of their budget on food items.