How are TSH and weight loss related?

TSH (thyroid-stimulating hormone) is secreted by the pituitary gland and regulates thyroid function. Hypothyroidism (underactive thyroid) leads to elevated TSH and often weight gain due to a lowered basal metabolic rate. Conversely, hyperthyroidism (overactive thyroid) with suppressed TSH can cause weight loss. However, the relationship is nuanced: many individuals with mildly elevated TSH (subclinical hypothyroidism) do not necessarily gain weight, and weight changes depend on calorie balance, muscle mass, and overall metabolism. A single TSH measurement is insufficient to diagnose thyroid disease; additional tests like fT3, fT4, and antibodies are needed. If you experience unexplained weight changes along with abnormal TSH, medical evaluation is warranted. MyBody-X offers hormone tests that include TSH, but interpretation should always be done by a healthcare professional.