I managed to find this graph of wheat consumption in a set of countries
(as the print doesn't show up clearly, they are in order:
China,India ,USA ,Russia ,France,Canada,Germany,Turkey,Pakistan ,Australia,Ukraine, UK,Iran ,Argentina ,Kazakhstan,Poland ,Egypt ,Italy,Romania ,Uzbekistan .
I used data from the WHO to show the obesity levels in those countries
I really can't see any correlation at all.