Recent data from our laboratories show that high-fat intake causes a decrease in hepatic CEACAM1 level by >50% within 3 weeks (11), and that this appears to play a causative role in diet-induced insulin resistance insofar as adenoviral-mediated delivery of CEACAM1 in liver reverses the metabolic abnormalities associated with increased fat intake, including insulin resistance, hepatosteatosis, and visceral obesity (12). The gene discussed is CEACAM1; the disease is Insulin resistance.