TNF and obesity due to melanocortin 4 receptor deficiency: Significantly lower BMI in postmenopausal women with osteoporosis than controls were observed, which is in agreement with the previous observations of Reid.[21] Other studies suggested no significant difference between BMI and osteoporosis.[22] On the other hand, there is some evidence that various cytokines as TNF-α and IL-6 are increased in obesity and decreased with weight loss, and it is believed that they play a role in causing insulin resistance.