Although the data on human subjects need to be strengthened by a much larger cohort of patients, they are consistent with a report finding a marked decline in hepatic CEACAM1 levels in 29% of 99 obese subjects with insulin resistance and non-alcoholic fatty liver disease, with a higher incidence of CEACAM1 loss in individuals with high-grade fatty liver and severe obesity, independently of type 2 diabetes (24). Here, CEACAM1 is linked to obesity due to melanocortin 4 receptor deficiency.