This study determines the effect of thyroid hormones on body mass index (BMI) in postmenopausal women. The study was conducted on 320 postmenopausal and premenopausal women attending clinics in Benin City, Nigeria. The results showed that postmenopausal women presented significantly higher (p<0.05) BMI and serum TSH level compared to the premenopausal women. Despite higher TSH, T3 and T4 were significantly lower (p<0.05) in postmenopausal women. These findings suggest that there might be lower T3 and T4 receptors in postmenopausal women. The implication is the observed increase in BMI in postmenopausal women which may be related to reduce BMR due to decrease levels of T3 and T4.

Keywords: Menopause, Body mass index, Tri-iodothyronine, Thyroxin