Weighty Matters: Public Health Aspects of the Obesity Epidemic

Part I -- Causes and Health and Economic Consequences of Obesity

Martin Donohoe, MD, FACP


December 12, 2007


This column is the first in a 5-part series that will describe public health aspects of the obesity epidemic. The prevalence of overweight and obesity has been rising in the United States for decades and has now reached epidemic proportions.[1] Part I describes the epidemiology and health consequences of obesity; part II discusses economic consequences of obesity, the obesity economy, and the roles of exercise, nutrition, and television; part III covers sodas, pouring contracts, and the food industry; part IV deals with obesity worldwide, as well as pathologic underweight and gluttony; and part V discusses treatments and public health measures to combat obesity. Obesity affects both men and women, but certain aspects of this medical and public health problem are unique to women, and these will be noted when relevant.


Epidemiology of Obesity in the United States

The average height/weight for American men and women today are, respectively, 5'9"/191 lbs and 5'4"/164 lbs.[2] Overweight is classified as a body mass index (BMI) (weight [kg] /height [m2]) ≥ 25.0 and obesity as a BMI ≥ 30.0. In 2005, 60.5% of US adults were overweight and 23.9% were obese.[1] The prevalence of obesity is nearly identical in men and women and ranges from 18% among adults aged 18 to 29 years to 30% among adults aged 50 to 59 years.[1] Obesity is more common among lower-income individuals, rural Americans, non-Hispanic blacks, and those with less education.[1,3] Low socioeconomic status is more closely linked to obesity for women than for men.[4]

Some anthropologists have attached cultural explanations to the obesity epidemic among African Americans. During the lean centuries of slavery, when food was intermittently scarce and dietary choices limited, being overweight was both a protective mechanism and a sign of good health. Persistence of some of these factors may partially explain obesity among African-Americans. However, poverty also plays a role because poor individuals tend to eat more calorie-laden fast food, and poverty is more common among African-Americans than among Caucasians.[5] Others have cited an association between food insecurity and obesity. Since African-Americans have higher levels of poverty and food insecurity and live in neighborhoods with fewer supermarkets and more fast-food restaurants, consumption of nutritious foodstuffs becomes impractical and is indeed more expensive, leading to overconsumption of low-cost, energy-dense (ie, high in added sugars and fat) foods.[4,6]

Causes of obesity include poor diet and inadequate exercise. Genetic, hormonal, and environmental factors play a significant role, as can 1 type of adenovirus.[7] A child with 1 overweight parent has a 40% chance of being overweight; with 2 overweight parents, it's 80%.[8] A number of medications (from birth control pills to antidepressants and antipsychotic drugs) can also contribute to weight gain. Interestingly, 25% of pets in the United States are obese and obese pets are more likely to have obese owners, implying that such owners overfeed or underexercise their animals.[9]


Health Consequences of Overweight and Obesity

Morbidity and Mortality

Obesity contributes to almost 300,000 deaths per year in the United States alone and is the second largest behavioral contributor to death after tobacco smoking.[10,11] Overweight and obesity in adulthood are associated with large decreases in life expectancy and increases in early mortality, similar in magnitude to those seen with smoking.[12]

Obesity is associated with increased risk for hypertension, diabetes, dyslipidemia, coronary heart disease, obstructive sleep apnea, gastroesophageal reflux disease, gallstones, asthma, pseudotumor cerebri, certain cancers (such as breast, colon, cervical, and uterine), major depression and suicidality, and possibly early onset of puberty in girls.[13,14] The prevalence of type 2 ("adult-onset") diabetes -- the type most commonly associated with obesity -- increased 33% (to 6.5%) from 1992 to 2000, and continues to climb.[15] Current patterns of overweight and obesity could account for 14% of all deaths from cancer in men and 20% of those in women.[16]

Overweight and Obesity in Childhood and Adolescence

Overweight and obesity rates have doubled in children and tripled in adolescents since 1980, spurring an epidemic of hypertension, type 2 diabetes, and the metabolic syndrome in children -- conditions rarely seen in this age group a few decades ago.[17,18,19] Obese children show decreases in physical and social functioning.[20] Severely obese children and adolescents have similar health-related quality of life as those diagnosed as having cancer.[21] Overweight and obesity in childhood are risk factors for obesity in young adulthood and middle age, so as the population ages, the contribution of obesity to US healthcare costs will increase.[22]

Obesity as a Barrier to Preventive Care

Obesity is a barrier to the receipt of preventive care, partially because obese individuals have more chronic health conditions. Addressing these conditions takes time during doctor visits, time that might otherwise be spent on provision of preventive services. It is also more time-consuming and difficult to perform certain procedures, particularly Pap smears, breast examinations, and colon cancer screening, on overweight persons.

The obese are less likely to be screened for colorectal cancer, which can be cured in its early stages.[23] Obese women receive fewer mammograms and Pap smears than their nonobese counterparts, despite having higher rates of breast and cervical cancer, both of which are curable when found early through screening.[24,25] To complicate matters, obese women are 20% more likely than their normal-weight counterparts to have false-positive mammograms, which leads to more unnecessary biopsies and associated anxiety.[26]



Obesity causes myriad health problems in both children and adults. The next column will describe the economic consequences of obesity; the "obesity economy"; and the roles played by nutrition, exercise, and television.