Medical Causes of Obesity

An Overview

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While we know that the causes of obesity are multifactorial and include the influences of the environment, genetics and socioeconomic factors, to name but a few, it is important to note that there are medical causes of obesity as well. These medical causes can range from underlying illnesses and metabolic disorders to medications with weight gain as an unwanted side effect.

Common Disorders

Some common disorders that can be associated with overweight and obesity include hypothyroidism, polycystic ovary syndrome, and Cushing syndrome, to name a few.

In hypothyroidism, for instance, the thyroid is not producing enough thyroid stimulating hormone (TSH) to maintain the production of the essential thyroid hormones which regulate metabolism, and the result may be a slow metabolism, which can lead to weight gain.

Depression has also been linked to obesity, and studies continue to investigate whether it is a cause or a result. It is known that some individuals overeat when they are depressed or feeling low, and this can contribute to weight gain. On the flip side of the coin, depression has been found to be prevalent among patients who are obese, particularly among women, and this may relate to issues of body image and societal pressures.

Other conditions that can indirectly lead to overweight and obesity include those which result in decreased physical activity due to loss of mobility. These conditions may include osteoarthritis, rheumatoid arthritis, other connective tissue disorders, musculoskeletal trauma, and stroke, among others.

Pregnancy is a condition that is necessarily related to weight gain, but after delivery, some women may find it difficult to lose all of the weight gained during pregnancy, and this may lead to the eventual development of overweight or obesity.

Chronic sleep deprivation has also been found to result in obesity, and getting less than seven hours of uninterrupted sleep on a regular basis can lead to weight gain and obesity.


Among medications that can cause weight gain, certain antidepressants are well known to do so. Several of the selective serotonin reuptake inhibitors (SSRIs) can cause weight gain as a side effect. An antidepressant medication that is notable for not typically causing weight gain is buproprion (Wellbutrin®); in fact, bupropion is associated with appetite suppression and can result in weight loss in some cases. Due to this, bupropion is sometimes chosen as an antidepressant in patients who are already overweight, obese, or otherwise concerned about weight gain.

Other medications that have been known to result in weight gain are anti-seizure medications such as divalproex (Depakote®), and second-generation antipsychotic medications such as olanzapine (Zyprexa®). Corticosteroids, such as prednisone,when used over a long term, are also well known to result in significant weight gain.

Several of the antiretroviral medications used to treat HIV/AIDS may result in a special kind of weight gain known as lipodystrophy. According to information provided by the National Institutes of Health (NIH), “lipodystrophy refers to the changes in body fat and metabolism seen in some people with HIV.” The NIH further notes that, while the exact cause of lipodystrophy remains unknown, it may be a result of HIV infection in itself or may be due to the antiretroviral medications used to treat HIV.

Of further note, current medications used to treat HIV are less likely to cause lipodystrophy, and many patients with HIV will never develop lipodystrophy.

It is important to keep in mind that many of these medications treat serious illnesses, and thus no medication should be stopped without the advice of a patient’s physician. The treating physician may be able to provide her patient with a newer alternative medication that does not result in weight gain.


1. Markowitz S, Friedman MA, Arent SM. Understanding the relation between obesity and depression: causal mechanisms and implications for treatment. Clin Pscyhol Sci Prac. 2008;15:1-20.

2. Side effects of HIV medicines: HIV and lipodystrophy. NIH Fact Sheet. Accessed April 16, 2014.  

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