7. Constipation vs. Diarrhea
Hypothyroidism impacts the health of your digestive system in a couple of ways. First, it slows metabolism and the action of the entire digestive tract. Second, it weakens the muscles that contract the colon and move stool along. The result is painful constipation.
Though hyperthyroidism also comes with muscle weakness, it typically speeds up your system and rushes food through the digestive tract. That tends to result in loose stools and wasted nutrition. Chronic diarrhea may also contribute to the weight loss common with hyperthyroidism.