According to the CDC, about 70% of adult Americans are overweight, and 35% are obese – roughly one in three American adults. This “obesity epidemic” developed rapidly here in the United States, where the obesity rate has more than doubled in the last forty years. While we have the dubious distinction of being the world’s obesity leaders, the epidemic is not confined to us; obesity rates are climbing in every country in the world that measures them.
Obesity is a complex condition with biological, genetic, behavioral, social, cultural, and environmental influences. For example:
- Individual behaviors and environmental factors can contribute to excess caloric intake and inadequate amounts of physical activity. The current high rates of obesity have been attributed to, in part, increased snacking and eating away from home, larger portion sizes, greater exposure to food advertising, limited access to physical activity opportunities, and labor-saving technological advances (Duffey & Popkin, 2011; Piernas & Popkin, 2011; Powell et al., 2011; Sallis & Glanz, 2009).
- Certain medical conditions (e.g., polycystic ovary syndrome) and prescription drugs (e.g., steroids, anti-depressants) can cause weight gain.
- Recent evidence suggests that inadequate sleep, prenatal and post-natal influences (e.g., maternal pre-pregnancy weight status, maternal smoking during pregnancy), chemical exposure, and stress may affect energy balance or obesity risk (Gore et al., 2015; Gundersen et al., 2011; Knutson, 2012; Shlisky et al., 2012; Weng et al., 2012).
- Race-ethnicity, gender, age, income, and other socio-demographic factors also can play a role in this complex health issue, as discussed elsewhere on this web-site. (See the sections on Obesity in the U.S. and Relationship Between Poverty and Obesity.)
Many of these and other contributing factors affect everyone at some point during their lives, at least to some extent, but those who are food insecure or low-income face additional challenges and risks.
Obesity’s Effects on Health
Based on numerous studies, we can say for certain that obesity is associated with an increased chance of developing many serious medical problems. Some of the diseases on the list probably won’t surprise you, like diabetes, but some might – cancer, for instance. Below is a table that runs through some of these diseases and the increased risk of developing them with obesity. Please note – this is only a partial list.
Type II diabetes risk increased 93-fold in women and 42-fold in men who are severely obese rather than normal weight.1,2
Sudden cardiac death 40-fold increase in morbid obesity.3
High blood pressure greater than 3-fold increase in risk with obesity.4,5
Sleep apnea 4-fold increase in the obese.6
Coronary heart disease 2-fold increase in obese men and 2.4-fold increase in obese women compared to normal weight.7
Stroke 1.6 fold increase with obesity.8
Arthritis of the legs eight-fold increase with obesity.9
Cancer risk of essentially all cancers except pancreatic and prostate cancer is increased up to 1.6-fold in the obese.10,11
Fatty liver disease seven-fold increase in obese individuals.12
Polycystic ovary syndrome five-fold increased risk, obese compared to normal weight women.13
Female Infertility three-fold increase with even borderline obesity.14,15
Erectile dysfunction Up to 3-fold increase with obesity.16
Cognitive impairment 3-fold (or greater) increase with obesity.17
Given that obesity increases the risk of so many health problems, you might be tempted to conclude that obesity shortens one’s life. If so, you’d be right. Numerous studies have indeed linked obesity with a shorter lifespan. Here are a few eye-openers taken from the medical literature:
- Obesity is associated with a greater risk of death across the age spectrum. The increase is strongest in young adults but persists through old age.18
- If you are morbidly obese when you turn 50, your risk of dying that year is 3 times higher than it is for a normal weight individual.19
- Morbidly obese men 25-34 years old are 12 times more likely to die than their normal-weight counterparts.20
- Colditz GA, Willett WC, Rotnitzky A, Manson JE. Weight gain as a risk factor for clinical diabetes mellitus in women. Ann Intern Med. 1995;122:481–486.
- Chan JM, Rimm EB, Colditz GA, Stampfer MJ, Willett WC. Obesity, fat distribution, and weight gain as risk factors for clinical diabetes in men. Diabetes Care. 1994;17:961–969.
- Alexander JK. The cardiomyopathy of obesity. ProgCardiovasc Dis. 1985;27(5):325–334.
- Kannel WB, Brand N, Skinner JJ, et al. The relation of adiposity to blood pressure and development of hypertension: the Framingham study. Ann Intern Med. 1967;67:48–59.
- Willett, WC, Dietz, WH, Colditz, GA. Guidelines for healthy weight. N Engl J Med 1999; 341:427.
- Somers VK, White DP, Amin R, Abraham WT, Costa F, Culebras A, Daniels S, Floras JS, Hunt CE, Olson LJ, Pickering TG, Russell R, Woo M, Young T. Sleep apnea and cardiovascular disease: an American Heart Association/American College of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing. J Am CollCardiol.
- Hubert HB, Feinleib M, McNamara PM, et al. Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study. Circulation. 1983;67:968–976.
- Strazzullo P, D’Elia L, Cairella G, Garbagnati F, Cappuccio FP, Scalfi L. Excess body weight and incidence of stroke: meta-analysis of prospective studies with 2 million participants. Stroke. 2010 May;41(5):e418-26. Epub 2010 Mar 18.
- Lee R, Kean WF. Obesity and knee osteoarthritis. Inflammopharmacology. 2012 Apr;20(2):53-8.
- Guh DP, Zhang W, Bansback N, Amarsi Z, Birmingham CL, Anis AH. The incidence of co-morbidities related to obesity and overweight: a systematic review and meta-analysis. BMC Public Health. 2009 Mar 25;9:88.
- Renehan AG, Tyson M, Egger M, Heller RF, Zwahlen M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet. 2008 Feb 16;371(9612):569-78.
- Wanless IR, Lentz JS. Fatty liver hepatitis (steatohepatitis) and obesity: an autopsy study with analysis of risk factors. Hepatology. 1990;12(5):1106.
- Alvarez-Blasco F, Botella-Carretero JI, San Millán JL, Escobar-Morreale HF. Prevalence and characteristics of the polycystic ovary syndrome in overweight and obese women. Arch Intern Med. 2006;166(19):2081.
- Grodstein F, Goldman MB, Cramer DW. Body mass index and ovulatory infertility. Epidemiology. 1994;5(2):247.
- Rich-Edwards JW, Goldman MB, Willett WC, Hunter DJ, Stampfer MJ, Colditz GA, Manson JE. Adolescent body mass index and infertility caused by ovulatory disorder. Am J Obstet Gynecol. 1994;171(1):171.
- SH Larsen, G Wagner, BL Heitmann. Sexual function and obesity. International Journal of Obesity (2007) 31, 1189–1198.
- Gustafson D, Rothenberg E, Blennow K, Steen B, Skoog I. An 18-year follow-up of overweight and risk of Alzheimer disease. Arch Intern Med. 2003 Jul 14;163(13):1524-8.
- Stevens J, Cai J, Pamuk ER, Williamson DF, Thun MJ, Wood JL. The effect of age on the association between body-mass index and mortality. N Engl J Med. 1998 Jan 1;338(1):1-7.
- Adams KF, Schatzkin A, Harris TB, Kipnis V, Mouw T, Ballard-Barbash R, Hollenbeck A, Leitzmann MF. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med. 2006 Aug 24;355(8):763-78. Epub 2006 Aug 22.
- Drenick EJ, Bale GS, Seltzer F, Johnson DG. Excessive mortality and causes of death in morbidly obese men. JAMA. 1980 Feb 1;243(5):443-5.