Sudden weight gain can be alarming, especially if you haven't made any major changes to your diet or exercise routine.

There are a number of possible causes, including:

Medical conditions: Certain medical conditions, such as hypothyroidism, Cushing's syndrome, and polycystic ovary syndrome (PCOS), can cause sudden weight gain

Medications: Some medications, such as corticosteroids, antidepressants, and antipsychotics, can also lead to weight gain

Fluid retention: Fluid retention can cause a temporary increase in weight.

Changes in hormones: Hormonal changes, such as those that occur during menopause and perimenopause, can also contribute to weight gain

Stress: Stress can lead to the production of the hormone cortisol, which can promote weight gain, especially around the midsection

Lack of sleep: When you don't get enough sleep, your body produces more of the stress hormone cortisol, which can lead to weight gain

Quitting smoking: Many people gain weight after quitting smoking.