What Raises the Risk of Obesity: Behaviors, Stress, Medicines, Genes and Surroundings

Obesity is a complex, costly chronic disease shaped by many factors. Knowing them helps individuals and communities take steps to prevent and reduce it.

Health behaviors

• too little physical activity
• unhealthy eating — too many highly processed foods or added sugars, including sugary drinks, and too little fiber and fruits and vegetables
• too little or poor-quality sleep
• too much screen time — TV, computers and video games

Stress

Long-term stress affects the brain and can trigger high levels of hormones such as cortisol, which help regulate energy balance and hunger. High levels can increase appetite and promote inflammation.

Health conditions and medicines

Some conditions can lead to weight gain, obesity or insulin resistance: Cushing syndrome, polycystic ovary syndrome and an underactive thyroid.

Some medicines can cause weight gain, for example by disrupting the brain's hunger signals:

• psychiatric medicines, such as antipsychotics and antidepressants
• steroids
• some hormonal birth control, such as progestins
• anti-seizure and mood-stabilizing drugs
• certain blood pressure and diabetes medicines

Genes

In rare single-gene disorders — such as Bardet-Biedl syndrome and Prader-Willi syndrome — genes directly cause obesity. More often, many genes together influence hunger, fullness and metabolism.

Where people live, learn, work and play

These conditions shape people's ability to make healthy choices:

Some chemicals in the environment may also disrupt how the body works and cause weight gain; research continues.

Sources

Based on "Risk Factors for Obesity," Centers for Disease Control and Prevention; a work of the United States government in the public domain.