Weight gain is often caused by an unhealthy diet, such as eating a lot of sugary foods, drinking a lot of alcohol, and a sedentary lifestyle. However, there are cases where people gain weight despite eating in moderation and exercising. The cause is a number of underlying health problems, according to the health website Healthline (USA).

Common causes of unexplained weight gain that people should not ignore include:

Hormonal imbalance

Hormones play an important role in regulating body weight. Health problems that affect the body's hormonal balance, such as hypothyroidism, can lead to weight gain. Untreated hypothyroidism slows down the body's ability to burn calories. As a result, people gain weight despite no changes in diet or exercise.

Similarly, polycystic ovary syndrome, a common hormonal disorder in women, can cause insulin resistance and weight gain. A study published in The Journal of Clinical Endocrinology & Metabolism found that hormonal imbalances caused by polycystic ovary syndrome can disrupt metabolism, leading to increased fat storage.

Side effects of the drug

Certain medications can contribute to weight gain. Antidepressants, antipsychotics, and corticosteroids have the side effect of increasing appetite, which can lead to weight gain.

Research published in The Lancet Psychiatry found that antipsychotics such as olanzapine and clozapine are more likely to cause weight gain than other drugs. If you suspect your weight gain is a side effect of your medication, talk to your doctor.

Sleep disorders

Not getting enough sleep or poor quality sleep can disrupt your hormone balance and increase your appetite, leading to weight gain. The hormones affected are leptin and ghrelin, which regulate hunger and satiety.

Additionally, conditions like sleep apnea and insomnia also contribute to weight gain by slowing down the body's metabolism, reducing the number of calories burned each day, according to Healthline .