Could it be my Thyroid?

Doctor, could it be my thyroid? from our new “Why Am I Overweight?” Series

Understanding the infamous and mysterious thyroid gland

There are a lot of misunderstandings about the role of the thyroid gland in how people gain or lose weight. As an endocrinologist, I see patients daily who have questions about supplements, non medical treatments and internet conversations about thyroid symptoms, but how does it really work?

The thyroid is the mysterious organ in the front of the neck that moves up and down when you swallow. You can actually see it if it is enlarged or irregular. For a small gland, it has a big reputation and is blamed for many problems – especially weight changes.

The thyroid is one of the areas responsible for setting the metabolic rate:  the rate in which calories are burned for energy. However, this function is more precisely regulated by another part of the endocrine system, the pituitary gland (the master gland). The thyroid signals the body to regulate important functions through hormones like T4 which is converted to the active form T3 in the liver.

So why not just adjust the hormones produced by the thyroid gland to lose weight?

It’s not that simple. How the thyroid functions affects the whole body. If your thyroid is overactive (producing too much hormone) it can cause you to burn more than just fat for energy but your muscle as well. This is known as “Hyperthyroidism” and it also causes excessive appetite and carbohydrate craving. About half the people with hyperthyroidism will actually gain weight. Because the hormones cause muscle to be burned for energy, it can result in a higher proportion of fat to muscle in the body. That’s not good as the amount of muscle you have is associated with your metabolic rate. The more muscle you have can mean the more fat you burn, so it’s important to keep weight loss targeted at fat.

Doctor checking Thyroid
On the other side, an underactive thyroid or “Hypothyroidism” slows the metabolic rate and causes weight gain. It’s what you might hear about most often and it can cause people to have less energy, become more tired and ultimately less active. Interestingly, they also tend to not be as hungry. If you have this condition you may have increased weight gain but most of the extra pounds are caused by fluid retention. “Slow thyroid” is often blamed as the culprit behind someone gaining a large amount of weight, but the average weight gain is only around 5-10 pounds.

Symptoms of an underactive thyroid might include:

      • tiredness
      • weight gain
      • depression
      • being sensitive to the cold
      • dry skin and hair
      • muscle aches

How do you know if your weight is being affected by an overactive or underactive thyroid?

A simple blood test will give you the answer. People who have unexpected weight gain or a family history of thyroid disease, should consult a doctor.  Replacing a hormone that you are missing is important for overall health.

Gaining weight is usually caused by multiple factors. If you blame the thyroid, you may miss out on the real cause of weight gain. If you have questions about your weight, contact us to schedule a consultation.


About Dr. K. Jean Lucas, MD, PI

Principal investigator and board certified in internal medicine and the subspecialty of endocrinology, Dr. Lucas started Lucas Research in 2004 to apply her years of patient caring into moving medicine forward. She completed her undergraduate education at Duke University and attended medical school at The University of North Carolina at Chapel Hill. She did her internal medicine residency at Carolinas Medical Center in Charlotte, N.C. and her internship at Pitt Memorial Hospital in Greenville, N.C. Her endocrinology fellowship with a medical faculty appointment was completed at Duke University Medical Center.