The thyroid is a small, butterfly shaped endocrine gland located in your neck that produces three hormones: Thyroxine (T4), Triiodothyronine (T3) and Calcitonin. These hormones are secreted into the blood, and two of them, T3 and T4, directly impact your metabolism. How? These hormones regulate how quickly your body’s cells work. If your thyroid secretes too much T4 and T3, your cells will become charged and start working faster than normal – this is called Hyperthyroidism, or overactive thyroid. If your thyroid secretes too little of the hormones, your cells will slow. This condition is called Hypothyroidism, or underactive thyroid.

So how does this over or under production of T4/T3 impact your metabolism? T3 and T4 control your heart rate, body temperature and, as it relates to metabolism, they also regulate how quickly your intestines process foods and how fast calories are burned. The condition of under-production of T3 and T4, commonly referred to as Hypothyroidism, can make it impossible to lose weight if not treated. While scientists don’t fully understand why an underactive thyroid causes weight gain or prevents weight loss, they suspect it’s due to:

· Slow metabolism

· Lack of energy that leads to less activity

· Changes in how your body processes, stores and burns off fat and glucose

· Fluid retention

Hypothyroidism  

Hypothyroidism occurs when the thyroid stops producing enough T3 and/or T4 and metabolic function becomes impaired.  The most common causes of hypothyroidism are autoimmune failure (Hashimoto’s Thyroiditis) and surgical removal or destruction of the thyroid gland which occurs when a goiter is removed or to treat thyroid cancer. 

Signs and symptoms of hypothyroidism (underactive thyroid) include: 

• Fatigue 
• Sleepiness 
• Mood swings 
• Forgetfulness 
• Weight gain 
• Depression/irritability 
• Muscle cramping and aching 
• Weakness 
• Decreased perspiration 
• Changes in blood pressure 
• High cholesterol 
• Swelling in legs 
• Blurred vision 
• Cold intolerance 
• Hoarse voice 
• Heavy menses 
• Coarse, dry hair and skin 
• Hair loss (on head and/or body) 
• Constipation

Should I get my thyroid checked? 

If you have excess weight, taking a simple thyroid blood test is probably a good idea.  There is evidence that suggests undiagnosed thyroid disease is directly correlated to obesity, so if you are struggling with weight gain, or if you think you may have diabetes or insulin resistance, evaluating your thyroid function is a great first step to identifying underlying health issues.  

The best tests to evaluate your thyroid are: 

TSH – TSH is most commonly used as a screening test for thyroid disease.  TSH is sent from the pituitary gland, where it is produced, to the thyroid gland in order to direct the thyroid’s hormone production. TSH is inversely related to thyroid hormone levels – when levels of TSH rise, thyroid hormone levels decrease.  If thyroid hormones are high, less TSH is produced.  If you have a TSH value that is between 3 and 4.5, you should consult with your healthcare provider about additional thyroid disease testing.

T3 and T4 levels – T3 and T4 are commonly tested with TSH.  T3 is the active thyroid hormone.  Often, low T3 levels are linked to failed weight loss efforts. T4 acts as the storage hormone – it starts out inactive and is converted to T3 when the body needs it.

Thyroid Antibodies – Because autoimmune destruction of the thyroid is the most common cause of hypothyroidism, checking the antibodies produced in the thyroid is a good way to measure thyroid health.  Typically, thyroid peroxidase antibody (TPO) and thyroglobulin antibody (TgAb) are tested to determine the severity of hypothyroidism.  TPO is usually detected in individuals with Hashimoto’s disease and Graves’ disease. 

Interpreting thyroid blood test results: 

Comparing TSH with T4 values can provide you and your healthcare provider with a picture of a possible thyroid issue.  For example: 

• Normal TSH + normal T4 = normal thyroid function 
• Low TSH + high T4 = hyperthyroidism/overactive thyroid 
• High TSH + low T4 = hypothyroidism/underactive thyroid 
• Low TSH + low T4 = low thyroid function due to another problem, such as pituitary gland dysfunction 

What now? 

If the results of your thyroid screening tests come back normal, congratulations!  That’s great news!  While it may be disconcerting to learn that thyroid function is not the main culprit behind your weight issues, you can now move on to other blood tests that will help you identify the source of your weight struggle.  However, if your thyroid testing yields results that are out of normal range, it’s time to consult with a healthcare provider.  You may need to consider medical intervention for your condition.  At the very least, you will likely need to make lifestyle and dietary changes. 

Diet and Weight Loss Tips for those with Hypothyroidism: 

Dietary Changes – making simple changes to your diet will greatly impact your weight.  These 6 quick changes will make the greatest impact: 

• Eat more fruits and veggies 
• Increase your fiber intake 
• Consume protein 
• Limit cruciferous foods 
• Eat healthy fats 
• Limit simple carbs and sugars 

Hydrate – Drinking plenty of water will keep your metabolism working efficiently by improving digestion and decreasing water retention and bloating.  Consuming water can also curb your appetite. Ideally, you should consume at least 64 ounces of water per day. 

Exercise – In order to improve metabolic function, exercise at a moderate intensity for at least 5 days a week for a minimum of 30 minutes per session.   

Sleep – lack of sleep is directly correlated to obesity and a slowed metabolism.  To optimize your weight loss, you should sleep for at least 7 hours per night. 

To learn more about thyroid disease, you can talk to your healthcare provider or visit the following Web sites for more information: 

• The American Thyroid Association: www.thyroid.org 
• The American Association of Clinical Endocrinologists: www.aace.com 
• The Endocrine Society: www.endo-society.org