IER3 and obesity due to melanocortin 4 receptor deficiency: In contrast, after 20 weeks of HFD consumption WT mice gained 92% in their body weight (48 ± 2 gm from 25 ± 1), whereas, IEX-1−/− mice had their body weight increased by only 44% (37 ± 3 gm from 25 ± 2; Fig. 2A,B), demonstrating that IEX-1−/− mice were resistant to HFD-induced obesity (Fig. 2C).