Decreased thyroid function (both overt and subclinical) is more frequent in overweight and obese people but hypothyroidism as cause of obesity is rare. Borderline or slightly elevated values of thyrotropin without other signs of autoimmune inflammation (elevated antibodies, changes at ultrasonography) are mostly consequence of hormonal/cytokine reactions to obesity, especially to hyperleptinemia.
However, they simultaneously represent metabolic and cardiovascular risk factor.