You might want to include a "constipation index" of some sort as an indicator of thyroid function. Hyperthyroid increases GI motility and hypothyroid lowers it. Seems that hyper- also goes along with thin, "eat crisps everyday and don't gain a pound" types
and hypo- the reverse. In the middle is a group that is in a sort of transitory state moving back and forth between the two in a sub-clinical limbo.