Thyroid Nation

Do you experience chronic constipation or diarrhea, or do you fail to completely digest and absorb food completely you eat? Do you experience stomach pain? Are you gaining or losing weight or experiencing changes in your appetite although you haven’t changed your diet?

Especially if you experience these symptoms along with any of a number of other issues like sensitivity to heat or cold, dry, coarse skin and hair, fatigue and mental lethargy, nervousness and irritability or difficulty sleeping, muscle weakness or tremors, or heart palpitations, consider the possibility that your thyroid isn’t functioning optimally.

Basal Metabolism

Your thyroid, a very small gland in the front of your neck just under your Adam’s apple, regulates virtually every cell in your body, impacting many bodily functions. The influence this tiny gland has on your overall health and well-being is tremendous because, in addition to impacting various processes directly, your thyroid gland controls basal metabolism. Among the processes regulated by your metabolism are fat metabolism, carbohydrate metabolism, protein synthesis, protein catabolism and insulin secretion. Basal metabolism is the way your cells use the energy they have absorbed from food during digestion. Too much or too little input from your thyroid can result in disruptions in that process. If your metabolism works too slowly or too quickly, your body doesn’t absorb and use nutrients efficiently from the food you eat. When this happens, the food you eat is poorly digested and poorly utilized calorie-for-calorie. Problems occur at the cellular level, and eventually you experience many different kinds of symptoms because various body systems aren’t getting the fuel they require.

How Your Thyroid Works

Let’s explore a more direct relationship between your thyroid and your digestion by taking a look at how your thyroid works. In response to chemical signals from your brain (TSH – Thyroid Stimulating Hormone), your thyroid gland secretes hormones, primarily T4 (Tetraiodothyronine). Your body, however, prefers T3 (Triiodothyronine). For the most part, T4 converts to T3 in your peripheral organs, one of which is your digestive system. You can think of T4 as an inactive form of thyroid hormone and T3 as its active counterpart. Clearly, there are several points in the process where things can go wrong or not work at the optimal level. If your thyroid suffers damage in some way, it sends out too much or too little T4. Many people have difficulty at the point of conversion, and there is too much or too little T3. The influence this tiny gland has on your overall health and well-being is tremendous. Click To Tweet There are additional complicating factors in the digestive process. Since healthy gut flora are important to the conversion process, if the flora are out of balance, they negatively influence it. Conversely, if there is a problem in the conversion process, it can negatively impact the health and balance of gut flora. In some ways, therefore, it is more accurate to call the relationship between thyroid and digestion a reciprocal process.


Problems in digestion can occur even before your system metabolizes the food you eat. Digestion refers to how the body processes food in the gastrointestinal (GI) tract and eliminates food waste via the intestines. Although stimulated chemically, digestion is a mechanical process, and your thyroid hormones regulate that as well. Esophageal or intestinal peristalsis speeds up or slows down. Similarly, digestion in the stomach or intestines may speed up or slow down, or you might suffer from a reduced concentration of stomach acid and digestive enzymes. Hyperthyroidism links most often to diarrhea. The symptoms represent a system running on high, with reduced transit time and absorption and wasted calories. There could be several reasons for this diarrhea including:

  • Fat malabsorption
  • Intestinal hypermotility
  • Hypersecretion of bile
  • Pancreatic enzymes and secretin in small intestine tissue
  • And increased intestinal transit time

Hypothyroidism, on the other hand, links most often to constipation with slower intestinal peristalsis, the contractions that move food waste out.


Your body is an amazing and complex system. Like an orchestra playing together in perfect harmony, your body has many parts, each with its own job to do, all working together in perfect harmony when you are healthy. You don’t even notice how amazing you are until something goes wrong! And if the something that goes wrong is your thyroid, it has an impact far greater than its size in relation to the rest of your body suggests.

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Questions or anything to add about digestion and the thyroid? We want your thoughts, please. You might just help someone else in need.