Overweight, Eats Chapati In The Evening Causing Cold And In Turn Fever. Alternative To Reduce Heat Content In Body?

Hi Doctor, My husband is overweight ,hes trying to reduce his weight by taking chapathi daily in the evening,but wheat is causing heat content in his body and in turn hes gettting cold and in turn fever , so Can you please suggest what could be a better choice to reduce this heat while taking chapathis, and one more doubt He use to take buttermilk everyday along with chapathi to compensate heat content, but he stops taking buttermilk when he get cold as he belives that taking buttermuilk when having cold increses cold.Is it true?