The Surprising cause of Exercise Fatigue

Not quite up to your usual stuff? Your thyroid—the body’s master hormone gland—might be the reason. 

- Alyssa Shaffer

CONSTANTLY PUSHING TO FINISH a workout? Struggling to keep your weight in check? Feeling a bit down in the dumps? Your diet, workout, and even your mindset might not be to blame—you might have a thyroid issue.

It’s only about two inches long, but your thyroid has a major impact on almost every cell in your body. This hormone-producing gland, which is shaped like a butterfly and sits just below the voice box, regulates your body’s metabolism and has a say on everything from energy levels to skin tone.

“The thyroid has an effect on about every organ system,” explains Hossein Gharib, M.D., a professor of medicine at Mayo Clinic College of Medicine and a past president of the American Thyroid Association (ATA). “When it’s not working right, it can make a big difference in how you look and feel.”