So many people wonder why they constantly deal with a lack of energy. The answer could be a low-functioning thyroid—even when blood tests say otherwise.

In Tired of Being Sick and Tired, Dr. Michael Berglund addresses the surprising hidden reasons why you, like so many other people, may be struggling to overcome exhaustion, depression, and weight gain.

If your thyroid isn't working properly, you can eat perfectly, take your vitamins, and still feel sick. What's worse, the typical blood test to determine low-functioning thyroid doesn't always give you the whole picture. Dr. Berglund explains the truth that your doctor may not be telling you, including: