Human growth hormone does two main things: It helps kids grow and affects how your body uses food for energy.

For growth, HGH tells certain cells in your bones and cartilage to multiply, especially during puberty, making you taller. After puberty, it keeps your body in shape. For metabolism, HGH boosts a hormone called insulin-like growth factor-1 (IGF-1), which works like insulin to control your blood sugar levels.