Hypothyroidism and Weight Gain
The thyroid gland is a small butterfly shaped gland in the neck with lobes on both sides of the trachea. This gland produces stores and releases two hormones, thyroxin and triiodothyronine, controlling the rate of metabolism in every cell in the body. Under certain circumstances this master gland of metabolism can produce too much or too little hormone. If there is too little of the thyroid hormones the condition is called hypothyroidism. Too much hormone results in hyperthyroidism.
Common symptoms of hypothyroidism include weight gain, fatigue, feeling cold when others are comfortable or warm, brittle nails and dry skin, and hair loss. Irregularity of menstrual periods, constipation, depression, and swelling in the lower legs are other symptoms of hypothyroidism. As the thyroid gland works harder to produce more thyroid hormones it enlarges and becomes palpable in the neck. This is called a thyroid goiter. Hypothyroidism is diagnosed with blood tests measuring thyroid stimulating hormone or TSH from the pituitary gland along with thyroxin (T4) and triiodothyronine (T3) released from the thyroid gland. A sonogram of the thyroid will reveal whether the gland is diffusely enlarged or if there are nodules present. A thyroid scan using radioactive iodine will determine if areas of the enlarged gland are “cold” or do not take up the iodine. Cold nodules may indicate a thyroid cancer.
The most common cause of hypothyroidism is thyroiditis or an inflammation of the thyroid gland. Other causes include inadequate production of thyroid stimulating hormone from the pituitary gland, surgical removal of all or part of the thyroid gland, or drugs that affect thyroid function. Once hypothyroid disease is diagnosed thyroid hormone replacement usually in the form of levothyroxine is begun to reverse the effects of hypothyroidism.
A major symptom of hypothyroidism is weight gain. The mechanism of weight gain in people who are hypothyroid is two fold. As a hormone that controls cellular metabolism in every cell in the body it is easy to see that lack of thyroid hormone will cause a lower cellular metabolism. This leads to both a lower metabolic rate and slower burning of calories and also fatigue. By products of fatigue are lower activity levels resulting in fewer calories burned and increased consumption of glucose rich foods in an effort to increase energy.
Patients often feel that once hypothyroidism is diagnosed and thyroid hormone replacement is begun weight loss will be simple. This is not the usual case. It takes an average of three to four weeks for the thyroid hormone to reach a steady state in the body. As the patient begins to feel better both eating habits and exercise levels need to change in order to lose the excess weight.
Patients who have gained weight may also experience something called metabolic resistance. Even after thyroid levels have been corrected it is difficult for these patients to simply reduce calories and lose weight. Their metabolism needs to be stimulated. The easiest way to stimulate the body’s metabolism is with vigorous exercise consisting of at least thirty minutes a day five days each week of aerobic activity. Patients who have been hypothyroid need to begin slowly under a doctor’s supervision but persistence will pay off with weight reduction.
Other important aspects of reversing weight gain once the hypothyroidism has been diagnosed is to make sure that the thyroid replacement is adequate. Since the TSH level is used to measure the adequacy of thyroid replacement this level should be in the low normal range. The range is 0.5 to 5.5 but most experts suggest thyroid hormone replacement should keep the level between 1.0 and 2.0.
