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Adult Obesity Causes & Consequences

Obesity is a complex health issue to address. Obesity results from a combination of causes and contributing factors, including individual factors such as behavior and genetics. Behaviors can include dietary patterns, physical activity, inactivity, medication use, and other exposures. Additional contributing factors in our society include the food and physical activity environment, education and skills, and food marketing and promotion.

Obesity is a serious concern because it is associated with poorer mental health outcomes, reduced quality of life, and the leading causes of death in the U.S. and worldwide, including diabetes, heart disease, stroke, and some types of cancer.


Healthy behaviors include a healthy diet pattern and regular physical activity. Energy balance of the number of calories consumed from foods and beverages with the number of calories the body uses for activity plays a role in preventing excess weight gain.1,2 A healthy diet pattern follows the Dietary Guidelines for Americans which emphasizes eating whole grains, fruits, vegetables, lean protein, low-fat and fat-free dairy products and drinking water. The Physical Activity Guidelines for Americans recommends adults do at least 150 minutes of moderate intensity activity or 75 minutes of vigorous intensity activity, or a combination of both, along with 2 days of strength training per week.

Having a healthy diet pattern and regular physical activity is also important for long term health benefits and prevention of chronic diseases such as Type 2 diabetes and heart disease.

For more, see Healthy Weight – Finding a Balance.

Community Environment

People and families may make decisions based on their environment or community. For example, a person may choose not to walk or bike to the store or to work because of a lack of sidewalks or safe bike trails. Community, home, child care, school, health care, and workplace settings can all influence people's daily behaviors. Therefore, it is important to create environments in these locations that make it easier to engage in physical activity and eat a healthy diet.

Watch The Obesity Epidemic to learn about the many community environmental factors that have contributed to the obesity epidemic, as well as several community initiatives taking place to prevent and reduce obesity.

Learn about strategies for a Healthy Food Environment and strategies to improve the environment to make it easier to be physically active.

Strategies to create a healthy environment are listed on the Strategies to Prevent Obesity page. More specifically, strategies to create a healthy school environment are listed on the CDC Adolescent and School Health website.


Do Genes Have a Role in Obesity?

Genetic changes in human populations occur too slowly to be responsible for the obesity epidemic. Nevertheless, the variation in how people respond to the environment that promotes physical inactivity and intake of high-calorie foods suggests that genes do play a role in the development of obesity.

How Could Genes Influence Obesity?

Genes give the body instructions for responding to changes in its environment. Studies have identified variants in several genes that may contribute to obesity by increasing hunger and food intake.

Rarely, a clear pattern of inherited obesity within a family is caused by a specific variant of a single gene (monogenic obesity). Most obesity, however, probably results from complex interactions among multiple genes and environmental factors that remain poorly understood (multifactorial obesity).3,4

What about Family History?

Health care practitioners routinely collect family health history to help identify people at high risk of obesity-related diseases such as diabetes, cardiovascular diseases, and some forms of cancer. Family health history reflects the effects of shared genetics and environment among close relatives. Families can’t change their genes but they can change the family environment to encourage healthy eating habits and physical activity. Those changes can improve the health of family members—and improve the family health history of the next generation.3,4

Learn more about genetics and obesity here: Obesity and Genomics.

Other Factors: Diseases and Drugs

Some illnesses may lead to obesity or weight gain. These may include Cushing's disease, and polycystic ovary syndrome. Drugs such as steroids and some antidepressants may also cause weight gain. The science continues to emerge on the role of other factors in energy balance and weight gain such as chemical exposures and the role of the microbiome.

A health care provider can help you learn more about your health habits and history in order to tell you whether behaviors, illnesses, medications, and/or psychological factors are contributing to weight gain or making weight loss hard.

Consequences of Obesity

Health Consequences

People who are obese, compared to those with a normal or healthy weight, are at increased risk for many serious diseases and health conditions, including the following:5,6,7

  • All-causes of death (mortality)
  • High blood pressure (Hypertension)
  • High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (Dyslipidemia)
  • Type 2 diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis (a breakdown of cartilage and bone within a joint)
  • Sleep apnea and breathing problems
  • Some cancers (endometrial, breast, colon, kidney, gallbladder, and liver)
  • Low quality of life
  • Mental illness such as clinical depression, anxiety, and other mental disorders8,9
  • Body pain and difficulty with physical functioning10

For more information about these and other health problems associated with obesity, visit Health Effects of Obesity.

For more information about these and other health problems associated with overweight and obesity, visit Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults [PDF 56KB].

Economic and Societal Consequences

Obesity and its associated health problems have a significant economic impact on the U.S. health care system.11 Medical costs associated with overweight and obesity may involve direct and indirect costs.12,13 Direct medical costs may include preventive, diagnostic, and treatment services related to obesity. Indirect costs relate to morbidity and mortality costs including productivity. Productivity measures include ‘absenteeism’ (costs due to employees being absent from work for obesity-related health reasons) and ‘presenteeism’ (decreased productivity of employees while at work) as well as premature mortality and disability. 14

National Estimated Costs of Obesity

The medical care costs of obesity in the United States are high. In 2008 dollars, these costs were estimated to be $147 billion.15

The annual nationwide productive costs of obesity obesity-related absenteeism range between $3.38 billion ($79 per obese individual) and $6.38 billion ($132 per obese individual)16.

In addition to these costs, data shows implications of obesity on recruitment by the armed forces. An assessment was performed of the percentage of the US military-age population that exceeds the US Army's current active duty enlistment standards for weight-for-height and percent body fat, using data from the National Health and Nutrition Examination Surveys. In 2007-2008, 5.7 million men and 16.5 million women who were eligible for military service exceeded the Army's enlistment standards for weight and body fat.17


1DHHS, AIM for a Healthy Weight, page 5. Available online: [PDF-2.17MB]

2Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA.Lancet. 2011 Aug 27;378(9793):826-37.

3Bouchard C. Defining the genetic architecture of the predisposition to obesity: a challenging but not insurmountable task. Am J Clin Nutr 2010;  91:5-6.

4Choquet H, Meyre D. Genetics of obesity: what have we learned? Curr Genomics. 2011;12:169-79.

5NHLBI. 2013. Managing Overweight and Obesity in Adults: Systematic Evidence Review

from the Obesity Expert Panel. [PDF - 93KB]

6Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. [PDF - 2MB]

7Bhaskaran K, Douglas I, Forbes H, dos-Santos-Silva I, Leon DA, Smeeth L. Body-mass

index and risk of 22 specific cancers: a population-based cohort study of 5•24 million UK adults. Lancet. 2014 Aug 30;384(9945):755-65. doi: 10.1016/S0140-6736(14)60892-8. Epub 2014 Aug 13.

8Kasen, Stephanie, et al. "Obesity and psychopathology in women: a three decade prospective study." International Journal of Obesity 32.3 (2008): 558-566.

9Luppino, Floriana S., et al. "Overweight, obesity, and depression: a systematic review and meta-analysis of longitudinal studies." Archives of general psychiatry 67.3 (2010): 220-229.

10Roberts, Robert E., et al. "Prospective association between obesity and depression: evidence from the Alameda County Study." International journal of obesity 27.4 (2003): 514-521.

11U.S. Department of Health and Human Services. The Surgeon General's call to action to prevent and decrease overweight and obesity. [Rockville, MD]: U.S. Department of Health and Human Services, Public Health Service, Office of the Surgeon General; [2001]. Available from: US GPO, Washington.

12Wolf AM, Colditz GA. Current estimates of the economic cost of obesity in the United States. Obesity Research.1998;6(2):97–106.

13Wolf, A. What is the economic case for treating obesity? Obesity Research. 1998 Apr;6 Suppl 1:2S-7S.

14Hammond RA, Levine R. The economic impact of obesity in the United States. Diabetes, metabolic syndrome and obesity : targets and therapy. 2010;3:285-295. doi:10.2147/DMSOTT.S7384.

15Finkelstein EA1, Trogdon JG, Cohen JW, Dietz W. Annual medical spending attributable to obesity: payer-and service-specific estimates. Health Aff (Millwood). 2009 Sep-Oct;28(5):w822-31. doi: 10.1377/hlthaff.28.5.w822.

16Trogdon JG, Finkelstein EA, Hylands T, Dellea PS, Kamal-Bahl. Indirect costs of obesity: a review of the current literature. Obes Rev.2008;9(5):489–500.

17Cawley J., Maclean J.C. , "Unfit for Service: The Implications of Rising Obesity for U.S. Military Recruitment," Health Economics 21, no. 11 (2012): 1348-66.