Loss of appetite is almost always seen elderly adults, and no physical cause may be found.There are different cause: -negative emotions such as sadness, depression. -Cancer can also cause decreased appetite.: Colon cancer Ovarian cancer Stomach cancer Pancreatic cancer Other causes of decreased appetite include: Inflammation of liver Chronic liver disease Chronic kidney failure Chronic obstructive pulmonary disease Dementia Heart failure Hepatitis HIV Hypothyroidism Pregnancy (first trimester) Use of certain medications, including antibiotics, chemotherapy drugs, codeine, and morphine Use of street drugs, including amphetamines (speed), cocaine, and heroin Take care Dr.Sagar Shrivastva