Glucose-dependent insulinotropic polypeptide [also known as gastric inhibitory polypeptide (GIP)] and its receptor (GIPR) may link overnutrition to obesity, insulin resistance, and type 2 diabetes.
The authors posit that an increase in circulating intestinally derived GIP, as a consequence of overnutrition, acts in the brain to impair hypothalamic leptin action, resulting in increased food intake and body weight gain.
In addition, observations in transgenic GIP receptor deficient mice indicate that GIP directly links overnutrition to obesity, therein playing a crucial role in the development of obesity and related metabolic disorders.