You should start thinking about medical causes of obesity when there is no other reasonable explanation for your weight gain. For example, if you start gaining weight rapidly in spite of maintaining the same level of nutrition and exercise, a medical investigation is in order to establish the cause. The more pronounced the weight gain and the shorter the period of time over which it occurs, the higher the odds of an underlying medical condition.
Abnormal fluid gain, in particular, can occur over a period of hours to days and sometimes constitutes a medical emergency. Among others, it can be the sign of a failing heart or failing kidney. For our purposes, however, this type of weight gain doesn’t greatly concern us. What we care about are increases in dry body weight (i.e., fat), as opposed to increases in water.
Another case which deserves a medical workup is someone who has been overweight most of his or her life, usually starting at a young age, with all routine weight loss measures failing or being only minimally effective. Generally, this scenario is due to ongoing lifestyle issues. However, endocrine disorders (among others) need to be ruled out.
Even if medical disorders are rarely the causes of obesity, it may still be worth pursuing a workup. Why? Simply because, if a medical abnormality is found, correcting the abnormality is likely to solve the weight problem.
The above being said, here’s a list of medical conditions leading to abnormal weight gain and/or inability to loose excess pounds: *
- Hypothyroidism (decreased thyroid activity), which causes a general slowing of one’s metabolism
- Hyper-cortisolism or Cushing’s syndrome (resulting in abnormally high cortisol levels in one’s body). Cortisol is the stress hormone, produced by the adrenal glands when the individual is under high stress, or in certain diseases where the secretion of cortisol becomes disinhibited. Abnormally high levels of cortisol in one’s blood will cause weight gain over time. This weight gain is especially notable on the trunk, neck and face, where the fat tends to deposit with predilection.
- Chronic sleep disturbances sometimes result in weight gain (partially due to increased stress and higher cortisol levels, and partially by increased food intake during the waking hours).
- Anxiety and depression are sometimes associated with weight gain due to increased food intake. This is mainly related to psychological factors. Some medications used in the treatment of depression, anxiety and other psychiatric disorders may also result in weight gain.
- Bulimia (the urge to consume inappropriately high amounts of food in a short time, sometimes with vomiting being induced after the binge), may sometimes lead to weight gain as well.
- PCOS (Polycystic Ovary Syndrome) is a deregulation of the hormonal balance which governs ovarian function and ovulation. It results in lack of ovulation, infertility, missed periods or erratic menstrual bleeding, and sometimes significant weight gain.
- Menopause can go either way: There are women who experience weight gain at menopause, but there are also women whose weight remains unchanged or decreases. This is dependent on how each individual body adapts to its new equilibrium.
- Arthritis can cause weight gain by the very fact it decreases mobility and thereby decreases the metabolic rate.
- Fibromyalgia (persistent muscle pains and body aches) can result in weight gain by the same mechanism.
- Similarly, any medical condition which prevents normal mobility may result in weight gain.
- Pregnancy is naturally associated with weight gain, due to the high estrogen and progesterone levels present during this state. Excessive weight gain during pregnancy is a fairly normal occurrence.
- Quitting smoking is frequently blamed for causing weight gain. This is believed to be mainly a psychological phenomenon, where the activity of smoking is replaced by eating.
* Please note that the above list is not exhaustive. We have just enumerated the most common causes of obesity. Multiple other medical causes of obesity may exist.