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Risk Factors for Obesity

At a glance

Obesity is a complex and costly chronic disease influenced by many factors. These factors include health behaviors, stress, health conditions and medications, genes, and people's environment. Knowing the risk factors can help individuals and communities take steps to prevent and reduce obesity.

Illustration of risk being measured as if it were on a scale.

Health behaviors

Certain health behaviors can contribute to excess weight gain and are risk factors for obesity:

Keep Reading: Healthy Eating Tips


Long-term stress can affect your brain and trigger your body to make high levels of hormones, such as cortisol. These hormones help regulate energy balances and hunger urges. High levels of these hormones can increase your appetite and promote cravings for foods that are high in fats and added sugars.1

Health conditions and medications

Some health conditions may lead to excess weight gain, obesity, or insulin resistance. These conditions include Cushing syndrome, polycystic ovary syndrome, or underactive thyroid.

Some medications may also cause weight gain by disrupting the brain's signals for hunger or through other mechanisms. These medications can include:

  • Psychiatric medications, such as antipsychotics and antidepressants.
  • Steroids.
  • Certain types of hormonal birth control, such as progestins.
  • Anti-seizure or mood-stabilizing drugs.
  • Certain blood pressure and diabetes medications.


In specific, rare, single-gene disorders, genes can directly cause obesity. Examples of these disorders are Bardet-Biedl syndrome and Prader-Willi syndrome.

It is more common for multiple genes to be responsible for a person's feelings of hunger, sense of fullness, and metabolism.2

Systems and environment

Health is influenced by the conditions in which people live, learn, work, and play. Health can also be influenced by forces and policies that shape these conditions. These factors affect a person's ability to make healthy choices and influence their risk of gaining excess weight and developing obesity.

Examples include:

Also, some chemicals in the environment can disrupt how our bodies work and cause excess weight gain. Understanding these factors and how we can use that knowledge to improve our health is ongoing.

  1. Scott KA, Melhorn SJ, Sakai RR. Effects of chronic social stress on obesity. Curr Obes Rep. 2012 Mar;1(1):16-25. doi: 10.1007/s13679-011-0006-3
  2. Mahmoud R, Kimonis V, Butler MG. Genetics of obesity in humans: a clinical review. Int J Mol Sci. 2022 Sep 20;23(19):11005. doi: 10.3390/ijms231911005