What are the mechanics of balance in our bodies?

Q: I am a 50-year-old woman with a history of depression. I recently developed an uncontrollable craving for sweets, which has increased my weight. Is it my depression or my medicine?

A: You are right to wonder about the cause of your craving. It could be triggered by your depression or by the medicine you are taking to manage it. Or by something else entirely.

Let's start with depression. Changes in appetite and weight are common symptoms. Weight can go up or down. Some people lose their appetite completely, along with all interest in food. Others with depression experience the opposite and can't stop eating.

Increased appetite and weight gain are more common in some types of depression than others. Seasonal affective disorder (SAD) is one example. SAD is a type of depression that seems to be triggered by reduced exposure to daylight. It typically comes on during the fall or winter months and subsides in the spring.

But there are no hard-and-fast rules about depression and appetite. Any type of depression can be accompanied by weight gain or loss.

Some medicines can also induce cravings and weight gain, including those that are used long-term to treat depression, psychosis, epilepsy and diabetes (except metformin).

You mentioned that your craving for sweets intensified recently. Have you started a new medication? Did your dose increase or decrease? A higher dose could have increased side effects, including cravings. On the flip side, a decreased dose may have led to the return of depression symptoms, including increased appetite. Or perhaps something else going on in your life caused your depression to get worse.

Your cravings could also be unrelated to your depression. If you never had cravings or weight gain when you were depressed before, it's not very likely that depression is causing them now.

Taking your age into consideration, it's possible that perimenopause or menopause is responsible. Some women experience an increase in cravings and appetite during that time. Or maybe your activity level has changed.

Finally, a medical problem may be causing a shift in your eating pattern. Among the more common are hypothyroidism (underactive thyroid), polycystic ovary syndrome, Cushing's disease or syndrome, and rare diseases of a part of the brain called the hypothalamus. Some people with fibromyalgia or chronic fatigue syndrome report periodic craving of food (not just sweets). The craving can be so severe that until they eat, they really don't think they can function.

Your craving for sweets is a new experience for you. Also, you are likely on medicines that can trigger appetite in some people. For those reasons, you should ask your doctor if your medicines (or a change in the dose) could explain your sudden craving. A general health review may provide more clues and help you get the problem under control.

• Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.