So many overweight patients report that because they can’t lose weight that it has to be due to a low metabolism and to the thyroid disorder of hypothyroidism. They believe that they need a thyroid medication to increase their metabolism and thus their weight loss. Unfortunately, the great majority of overweight patients don’t have hypothyroidism or low thyroid levels. The medical reality is that very few, perhaps less than 10% of individuals, have a low thyroid condition that would account for their weight gain and/or inability to lose weight. Some hypothyroid individuals may retain water to account for a weight gain, but only an increase in calorie intake can result in a weight gain from fat, not a decrease in thyroid function. I suggest that individuals who may think that they have a low thyroid function, hypothyroidism, see their physician to get a laboratory test for T-4 and Thyroid Stimulating Hormone, TSH, which will diagnose hypothyroidism. If it exists then your physician can treat the condition, but if there is no confirmation of hypothyroidism, then any thyroid medication is not warranted. Extra thyroid medication will burn muscle, decrease bone density, increase heart rate and irritability but not result in a clinically significant fat loss. Peter Vash, MD, M.P.H.