Hyperthyroidism and Weight Loss
What is the relationship between hyperthyroidism and weight?
Since the BMR in patients with hyperthyroidism is elevated, many patients with an overactive thyroid do,
indeed, experience some weight loss. Furthermore, the likelihood of
weight loss occurring is related to the severity of the overactive thyroid.
Thus, if the thyroid is extremely overactive, the individual’s BMR
increases which leads to increased caloric requirements to maintain
that weight. If the person does not increase the calories consumed to
match the excess calories burned, then weight loss will ensue. As
indicated earlier, the factors that control our appetite, metabolism, and
activity are very complex and thyroid hormone is only one factor in
this complex system. Nevertheless, on average the more severe the
hyperthyroidism, the greater the weight loss observed. Weight loss is
also observed in other conditions where thyroid hormones are elevated,
such as in the toxic phase of thyroiditis and
if one is on too high a dose of thyroid hormone pills. Since
hyperthyroidism also increases appetite, some patients may not lose
weight, and some may actually gain weight, depending on how much
they increase their caloric intake.
Why do I gain weight when hyperthyroidism is treated?
Because the hyperthyroidism is an abnormal state, we can predict that
any weight loss caused by the abnormal state would not be maintained
when the abnormal state is reversed. This is indeed what we find. On
the average, any weight lost during the hyperthyroid state is regained
when the hyperthyroidism is treated. One consequence of this
observation is that the use of thyroid hormone to treat obesity is not
very useful. Once thyroid hormone treatment is stopped, any weight that
is lost while on treatment will be regained after treatment is
discontinued.
Filed under: Medical Conditions
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