Obesity in America: CDC looks at prevalence and health risks

More than 4 in 10 U.S. adults have obesity, putting them at risk of chronic conditions like high blood pressure, type 2 diabetes, heart disease, stroke and some cancers. And 9.4% of adults have severe obesity, which is somewhat more common in women than in men.

There’s no significant difference between men and women in terms of obesity overall, though age mattered. Obesity prevalence was greater among those ages 40-59 (46.4%), compared to those who were younger (35.5%) and those who were older (38.9%). Education also made a difference. The prevalence of obesity was lower among those with a bachelor’s degree or more education, compared to those with less education.

That’s according to a National Center for Health Statistics brief released Tuesday, which estimated adult obesity and severe obesity from August 2021 to August 2023.

According to the report, “Obesity is defined by body mass index (BMI), which has limitations. Body fat may vary by sex, age and race and Hispanic origin at a given BMI level. BMI does not measure body fat directly, nor does it provide information on body fat distribution. The distribution of excess body fat, especially visceral fat, contributes to the risk of cardiovascular and metabolic disease. Despite these limitations, BMI is a simple and inexpensive screening tool for conditions that may increase the risk of certain chronic diseases.”

BMI is calculated by taking a person’s weight in kilograms and dividing it by height in meters squared, rounded to one decimal place. Obesity is a BMI at or above 30, while severe obesity is at or above 40.

What’s wrong with BMI?

The American Medical Association last year said BMI is an imprecise measure of body fat, since it doesn’t consider differences between racial/ethnic groups, sexes and age. The group said it should be used alongside other measures such as visceral fat, body adiposity index, body composition, relative fat mass, waist circumference and genetic or metabolic factors, among others.

According to the association’s updated policy, “BMI is significantly correlated with the amount of fat mass in the general population but loses predictability when applied on the individual level.” And it specifically notes that BMI shouldn’t be used as the only reason to deny insurance coverage.

An alternative measure, called the body roundness measure, has been proposed. That measure includes height and waist circumference. There are online BRI calculators where you enter your height and waist and hip measurements. The formula itself is a little scary for do-it-yourselfers: 364.2−365.5×√(1−[waist circumference in centimeters/2π]2/[0.5×height in centimeters]2, according to a study in JAMA Network Open .

Good Morning America said there’s some resistance to the BRI, as well, with criticism that it favors a certain body type.

Obesity risk factors

The Centers for Disease Control and Prevention notes a number of risk factors for obesity, including health behaviors, stress, health conditions, medications, genes and the local environment.

Among the health behaviors, lack of physical activity, poor eating habits and not enough sleep are among the most impactful. Overuse of television, computers and video games, as well as time spent scrolling social media also may play a role in developing obesity.

Stress kicks off a cascade of hormone production, including excess cortisol. Hormones can increase appetite and “promote cravings for foods that are high in fats and added sugars,” per CDC.

Among medications tied to weight gain are psychiatric drugs, steroids, certain hormonal birth controls, mood-stabilizing drugs and anti-seizure medications and some blood pressure and diabetes medications.

Among the environmental factors that influence one’s weight are how easy it is to get healthy foods at an affordable cost, safe and easy access to physical activity spaces, community design, supportive environments like schools and whether they promote activity, access to high-quality health care, economic stability and safe housing and transportation, per CDC.