What I have found is that in some people, undiagnosed celiac will cause them to lose weight
and for others, they gain weight
. If you not familiar with what celiac is, its an allergy to gluten (wheat, barley, rye, etc.). If you have this and eat anything with gluten, you kill off the villi in your intestines which cause you bosy not to absord any nutrients - therefore causing many other health issues.