What are the main causes of overweight and obesity?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Overweight and obesity develop when the body stores excess fat, most often due to consuming more calories than are burned through daily activity. While overeating and a sedentary lifestyle are the leading causes, other factors—including genetics, hormones, medications, sleep patterns, stress, and certain medical conditions—can also contribute.

Because weight gain can stem from many overlapping causes, identifying the specific reason behind your symptoms is key to finding the right next step. A free, instant, online symptom check can help you better understand what may be driving your concerns and guide you toward appropriate care—no appointment or sign-up required.

Reviewed for medical accuracy: 07/20/2026

Important Next Steps

Discover likely causes of overweight or obesity Find if your weight needs evaluation See whether obesity points to another condition Find OTC options for weight-related issues Find obesity specialists near you Learn medically valid home remedies for obesity Understand if overweight needs a symptom check

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Explanation

Being overweight or obese happens when we eat more calories than our bodies use. This can happen if we eat a lot of unhealthy foods and do not exercise enough.

Main Causes:

Unhealthy Eating Habits: Eating lots of fast food, sugary drinks, and snacks can lead to gaining too much weight.
Lack of Physical Activity: Not moving around or exercising enough means our bodies don't burn off the calories we eat.
Genetics: Sometimes, people can gain weight more easily because of their genes.
Other Factors: Things like lack of sleep, stress, and certain medicines can also make it easier to gain weight.

Making small changes, like eating more fruits and vegetables and playing outside, can help manage weight. Remember, it's important to talk to a doctor if you have concerns about weight. If you're experiencing any symptoms or health concerns, check your symptoms with Ubie's free AI-powered symptom checker to help understand what might be going on.

(References)

Wright SM, & Aronne LJ. (2012). Causes of obesity. Abdominal imaging, 22426851.
Kuźbicka K, & Rachoń D. (2013). Bad eating habits as the main cause of obesity among .... Pediatric endocrinology, diabetes, and metabolism, 25577898.
(2000). Obesity: preventing and managing the global epidemic. .... World Health Organization technical report series, 11234459.

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