26/11/2025
https://whatsapp.com/channel/0029VamlZb3AzNbrYHd82W2a/229
Why does treating subclinical hypothyroidism in obese individuals not lead to weight loss?
Because in obesity, a mildly elevated TSH is usually the result of obesity, not the cause of it. Excess adipose tissue produces leptin, which stimulates TRH release from the hypothalamus, leading to a mild, physiological rise in TSH—an adaptive state known as adiposity-driven hyperthyrotropinemia . Importantly, free T4 levels and tissue thyroid hormone action remain normal, so basal metabolic rate, thermogenesis, and lipolysis are not significantly reduced.
Although many people believe that hypothyroidism causes obesity, there is little evidence that mild thyroid dysfunction contributes meaningfully to weight gain. Slight TSH elevations are common in obese children, and TSH normalizes with weight loss, confirming that the rise in TSH is physiological rather than pathological and does not warrant therapy.
Therefore, giving levothyroxine may correct the TSH value, but it does not treat the underlying obesity or increase energy expenditure. Multiple randomized trials show that treating subclinical hypothyroidism normalizes TSH but leads to no reduction in body weight, BMI, waist circumference, or body-fat percentage.
Thus, treating the TSH does not treat the obesity, because the metabolic rate was already essentially normal. Treatment may still be indicated for other reasons, but weight reduction should not be expected.
