Unintentional weight loss is often a consequence of physiological and psychological disorders and should be promptly investigated.

Weight Loss

A person’s weight normally fluctuates within a limited range. Changes in diet or exercise could reduce weight some more. This weight loss is intentional, hence is not a cause for concern. On the other hand, sudden and unintentional weight loss requires immediate medical attention, as it could predict the presence various serious disease conditions.

An individual’s weight is determined by the total calorie intake and the rate at which the calories are burnt through metabolism or activity. Various physiological, psychological and social factors alter these components. A decrease in appetite and therefore total calorie intake, and an increased rate of metabolism or activity level are associated with weight loss.

Weight loss more than 4.5 kg or more than 5% of usual body weight over a period of 6 to 12 months is considered to be clinically important and should not be ignored. Further weight loss can affect the normal physiological functions of the body, and could even affect various organs.

Malnutrition is a common cause of weight loss. Malnutrition is often due to social factors like poverty or unavailability of food. In other cases, malnutrition may occur due to inability or lack of inclination to eat, or a problem with absorption of nutrients from the intestines.

Some of the health-related disorders that are associated with weight loss are listed below:

  • Cancer: Any person complaining of sudden and significant loss of weight should be evaluated for a hidden cancer, especially if no other cause is evident. Weight loss is a major symptom of cancer. Patients with cancer produce substances like cachectin and interleukins that are responsible for weight loss. Increased metabolism may be responsible for weight loss in patients with blood cancer.
  • Hormonal Diseases: Hormonal diseases are also common causes of weight loss. Conditions like hyperthyroidism increase the metabolic rate. Less commonly, pheochromocytoma, adrenal insufficiency, hypercalcemia and hypopituitarism cause weight loss. A history of symptoms, a complete physical examination and blood tests are used to diagnose these conditions.
  • Infection and Inflammation: Infections are commonly associated with weight loss due to an increase in metabolic rate accompanied by a decrease in appetite and calorie intake. Various infections like lung abscess, HIV, fungal diseases, and subacute bacterial endocarditis (infection of the heart) cause unintentional weight loss. Tuberculosis should be suspected in a patient with chronic cough, low-grade fever in the evenings and weight loss. These conditions are diagnosed through physical examination, blood tests and chest x-rays.
  • Neurological Disorders: Brain injury and neurodegenerative diseases like Parkinson’s disease and Alzheimer’s disease may result in a neglect of regular eating and therefore result in loss of weight. In addition, the patient may suffer from other complications like constipation. The medications used in the treatment of these conditions could also interfere with regular eating patterns.
  • Heart Diseases: Patients with cardiac diseases often experience decreased appetite and increased metabolism. Also, dietary restrictions in such patients may cause weight loss. Patients with severe congestive heart failure produce substances in the blood called cytokines, which result in symptoms like weight loss, wasting of muscle, and loss of appetite. Symptoms of cardiac disease are usually obvious in these patients.
  • Lung Diseases: Besides lung infections, conditions like severe chronic obstructive pulmonary disease and breathlessness are also associated with weight loss. Symptoms of lung disease should be looked out for in a patient with weight loss.
  • Digestive System Disorders: Digestive system disorders can reduce appetite and the absorption of nutrients from food, thereby resulting in weight loss. These disorders include stomach and intestinal ulcers, celiac disease and pancreatitis. In addition, dental problems may also be associated with reduced food intake and therefore weight loss. Worm infestations are common causes of weight loss or failure to gain weight in children despite adequate food intake.
  • Kidney Diseases: Kidney diseases may be associated with weight loss due to loss of protein in the urine, and the associated nausea and vomiting. However, in later stages of kidney disease, the weight may increase due to accumulation of fluid.
  • Medications and Alcohol: Medications are commonly associated with adverse effects like nausea, vomiting, loss of appetite, and altered taste. In addition, they could interfere with the absorption of certain nutrients or cause diarrhea, thus contributing to weight loss. Diuretics may cause weight loss by reducing the water content of the body. Alcohol impairs the body’s ability to absorb nutrients and vitamins and alters metabolism, resulting in weight loss.
  • Psychological Disorders: Psychological disorders like depression and anxiety often result in decreased appetite and loss of interest in eating. Conditions like anorexia nervosa result in the patients starving themselves and vomiting out any excess food that they may eat. Social factors like isolation and financial hardship are also responsible for the weight loss.

Frequently Asked Questions (FAQs)

1. Which doctor should I visit in case I suffer from unintentional weight loss?

You should visit your general physician in case you suffer from unintentional weight loss. Your doctor will diagnose the cause of weight loss based on your history and after conducting examination and various tests.

2. Why should you consider unintentional weight loss as a serious problem?

Unintentional weight loss could reflect a serious underlying disease including cancer. Such conditions may be completely cured if treatment is started early. It is therefore necessary not to ignore sudden and unintentional weight loss and detect the underlying problem at the earliest to reduce complications.


  1. Stajkovic S, Aitken EM, Holroyd-Leduc J. CMAJ March 8, 2011 vol. 183 no. 4 443-449
  2. Bouras EP, Lange SM, Scolapio JS. Rational Approach to Patients With Unintentional Weight Loss. Mayo Clin Proc. 2001;76:923-929
  3. Huffman GB. Evaluating and Treating Unintentional Weight Loss in the Elderly. Am Fam Physician. 2002 Feb 15;65(4):640-651

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