Patients are urged to immediately notify their physician if they notice any of the following:

• A 5 percent reduction in body weight over the course of a few weeks
  
• A 10 percent reduction in body weight over six months
  
• A significant increase in body weight over a short period of time
  
• Weight changes that exceed 5 pounds (2.3 kilograms) in a week during treatment, with perhaps the exception of weight loss associated with bariatric (obesity) surgery
  
• Other symptoms that occur in tandem with the weight change
  

Unexplained weight changes - especially sudden, inexplicable weight loss - may be the first sign of diseases such as cancer.

In order to determine the cause of the weight change, the physician will conduct a medical history and perform a physical examination. Questions about the patient's weight changes may include:

• How much weight has the patient lost or gained?
  
• When did the weight change first occur?
  
• Was the weight change sudden or gradual?
  
• Has the patient's thirst or appetite changed?
  
• Have there been any changes in the patient's physical activity level?
  
• Have there been any changes in the patient's bowel or bladder habits?
  
• Have there been any changes in the patient's mood?
  
• Was the patient recently ill?
  
• Does the patient have a food allergy or dietary intolerance?
  
• Does the patient have any other medical conditions?
  
• What medications is the patient taking?
  
• Is the weight loss accompanied by any other symptoms, such as fever, nausea or vomiting?
  

The physician may also order a nutritional assessment, blood tests, urine tests, imaging tests or other tests relating to the suspected cause of the weight loss.

Treatment for unexplained weight changes is directed at the cause of the weight loss or gain. In some cases, simple lifestyle changes can remedy the situation. For example, a combination of a well-balanced diet and exercise can help restore proper weight levels in people with either unintentional weight loss or weight gain.

In other cases, medical therapies may be necessary. Effective treatment of medical conditions can restore a patient's health and bring body weight back to a healthier level. Psychological counseling can help patients whose weight changes are related to conditions such as eating disorders or depression.

In extreme cases, a feeding tube may be used to help reverse unintentional weight loss, and a physician may recommend bariatric surgery to treat severe unintentional chronic weight gain that does not respond to noninvasive methods.