How do xenical pills work?

See below. Xenical works in the presence of dietary fat and reduces the absorption of dietary fat by approximately 30%. The body will naturally tap into existing body fat stores for energy, which will result in a loss of body fat provided a balanced diet and regular physical activity is undertaken.
Lipase Inibitor. Xenical inhibits (blocks) an enzyme called lipase that allows your intestines to absorb fatty acids (fat).