Unintentional weight gain can be caused by many different things.
As you age, our metabolism slows down. This can cause weight gain if you eat too much, eat the wrong foods, or do not get enough exercise.
A medical problem or use of certain medication may also make you gain weight.
Medications that can cause weight gain include corticosteroids and drugs used to treat bipolar disorder, schizophrenia, and depression.
Hormone changes can also cause unintentional weight gain. This may be due to:
- Cushing syndrome
- Hypothyroidism (underactive thyroid, or low thyroid)
- Polycystic ovary syndrome
Bloating, or swelling due to a buildup of fluid in the tissues can cause weight gain. This may occur with menstruation, heart or kidney failure, preeclampsia, or certain medications.
If you quit smoking, you might gain weight. Most people who quit smoking gain 4 - 10 pounds in the first 6 months after quitting. Some gain as much as 25 - 30 pounds. This weight gain is not simply due to eating more.