gpihbp1 is essential in lipid metabolism because it facilitates the efficient hydrolysis of triglycerides. Without gpihbp1, LPL cannot reach the capillary lumen, leading to impaired triglyceride breakdown and subsequent hypertriglyceridemia, a condition characterized by elevated levels of triglycerides in the blood. This is critical because proper lipid metabolism is necessary for maintaining energy balance and preventing cardiovascular diseases.