What causes weight gain?

Weight gain can be a natural result of fluctuations in hormonal processes, such as the menstrual cycle or pregnancy. However, most cases of unplanned or unintended weight gain are caused by taking in more calories than the body can use. Certain drugs can also cause weight gain, and unintended weight gain can be a symptom of a number of medical conditions or disorders. Weight gain that is sudden and rapid can be a sign of dangerous levels of fluid retention by the body.

Digestive causes of weight gain

Weight gain can be caused by digestive disorders including:

Endocrine system or hormonal causes of weight gain

Weight gain may be caused by endocrine or hormonal causes including:

  • Acromegaly (excess growth hormone in adults)
  • Amenorrhea, premenstrual syndrome, menstrual cycle effects
  • Cushing’s syndrome (excess cortisol production in the body)
  • Diabetes
  • Growth hormone deficiency
  • Hashimoto’s thyroiditis (autoimmune thyroid disease)
  • Hypopituitarism (underactive pituitary gland)
  • Hypothyroidism (underactive thyroid gland)
  • Pituitary tumor
  • Polycystic ovary syndrome (condition characterized by hormonal imbalance in women)
  • Pregnancy

Medications that cause weight gain

A number of drugs or medications may result in weight gain including:

  • Antiseizure drugs
  • Birth control pills
  • Certain antidepressants
  • Corticosteroids
  • Hypoglycemic agents for Type 2 diabetes
  • Lithium
  • Tranquilizers

Urinary causes of weight gain

Weight gain can also be caused by urinary disorders including:

Psychological causes of weight gain

Weight gain can also be caused by psychological disorders including:

Serious or life-threatening causes of weight gain

In some cases, weight gain may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

Questions for diagnosing the cause of weight gain

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your weight gain including:

  • How long have you been gaining weight?
  • Has the weight gain been rapid or gradual?
  • Do you feel anxious or under stress? Depressed?
  • Have you noticed any changes in your appetite or your eating habits?
  • Do you have any other symptoms?
  • Do you drink alcohol or use street drugs?
  • What medications are you taking?

What are the potential complications of weight gain?

Excessive weight gain is unhealthy regardless of cause. Because weight gain can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:


  1. Weight gain - unintentional. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003084.htm.
  2. Weight control. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/weightcontrol.html.
  3. Kahan S, Miller R, Smith EG (Eds.). In A Page Signs & Symptoms, 2d ed. Philadelphia: Lippincott, Williams & Williams, 2009.
  4. Moyer VA, U.S. Preventive Services Task Force. Screening for and management of obesity in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2012; 157:373.

What is weight gain?

Some types of weight gain are related to a natural process rather than a disease. For example, it is normal (and even necessary) to gain some weight during pregnancy, and weight gain accompanies normal growth in children. However, unplanned or unintended weight gain may become problematic and should be addressed. In most cases, taking more calories into the body than your body can use causes un... Read more about weight gainintroduction


What other symptoms might occur with weight gain?

Weight gain may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the digestive tract may also involve other body systems.

Symptoms that may occur along with weight gain

Weight gain may accompany symptoms related to different body systems including:

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 30, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Food, Nutrition and Diet