Answer
Leptin and insulin are hormones (enzymes) that function to regulate body weight through control of appetite and metabolic rate. They govern calorie intake and energy expenditure over periods of weeks to years.
Both leptin and insulin are adiposity monitors; they "tell" the brain how much fat the body has and they activate mechanisms to increase or decrease fat stores.
Leptin is produced by fat cells all over the body, and its level varies with the amount of body fat. The level of leptin informs the body of the degree of adiposity of the body. This knowledge is important because adipose tissue produce several important hormones. for example, adiponectin and resistin.
Insulin is secreted by the pancreatic beta cells (Islets of Langerhans). It is a digestive enzyme and hormone with several important influences on body weight:
It stimulates glucose and amino acid uptake
It promotes glycogen and fat synthesis
Like leptin it has receptors in the brain and functions as and indicator of fat storage.
Work Step by Step
Insulin's most important function is to enables cells to take up and utilize glucose.
