With increased appetite, the most common occult causes of involuntary weight loss are Hyperthyroidism Uncontrolled diabetes Disorders that cause malabsorption With decreased appetite, the most common occult causes of involuntary weight loss are Psychiatric disorders (eg, depression) Cancer Drug adverse effects Drug use disorder Table Table In some disorders that cause involuntary weight loss, other symptoms tend to be more prominent, so that weight loss is usually not the chief complaint.