COL6A3 and obesity due to melanocortin 4 receptor deficiency: Yet, seemingly contradictory to these compelling data, studies have reported decreased adipose COL6A3 mRNA expression in extreme obesity in the context of high inflammatory gene expression, and increased COL6A3 mRNA after profound fat loss in the same people17, as well as increased COL6A3 mRNA after a very low-calorie diet18.