IL1B and obesity due to melanocortin 4 receptor deficiency: IL-1β suppresses lipoprotein lipase (LPL) expression and activity.5 LPL is an enzyme that hydrolyzes triglyceride-rich lipoproteins and is expressed in a variety of tissues, including adipose tissue and muscle.18 It has been reported that overexpression of LPL reduced fat accumulation and insulin resistance in rabbits fed high-fat diets,19 indicating that elevation of LPL may protect against obesity.