Second, the changes in the expression of genes in the AT were much greater than those of sorted ATMs: for example, while sorted ATMs from HFD-fed mice expressed ∼2-fold higher levels of Tnf relative to NC mice, the total AT from these HFD-fed mice expressed ∼25-fold higher levels of Tnf. This is mainly due to the compounding effects of increased ATM numbers and their increased gene expression levels, and it may be one of the mechanisms by which obesity amplifies AT inflammation. Here, TNF is linked to obesity due to melanocortin 4 receptor deficiency.