Question

cathy went through gastric bypass surgery for her severe obesity. this has helped to lessen her appetite and lose weight because her remaining stomach produced less: pyy. leptin. ghrelin. orexin.

Explanation:

Gastric bypass surgery reduces the stomach's size. Ghrelin is mainly produced by the stomach. A smaller stomach means less ghrelin production. Ghrelin is an appetite - stimulating hormone. Less ghrelin leads to less appetite. PYY is produced in the intestines and suppresses appetite. Leptin is produced by fat cells. Orexin is produced in the hypothalamus.

Answer:

ghrelin.