Millions of Americans suffer from the symptoms of thyroid dysfunction without ever knowing it. In fact, it is estimated that more than 30 million women and 15 million men have an underactive thyroid or hypothyroidism. Our endocrine system is made up of the glands that produce the hormones that circulate in our bodies that are responsible for growth, repair, metabolism, energy and reproduction. The thyroid is one of these glands that when underactive can affect our health systemically in a negative way. What are some of the less conspicuous symptoms of a low thyroid? Feeling blue or unmotivated. Constipation. Difficulty sleeping. Overweight and having trouble shedding pounds. Low body temperature,.