US obesity rates have tripled over the last 60 years

Nearly 70% of adults in the US are either overweight or obese.

According to nationwide surveys the National Institutes of Health has conducted since the early 1960s, US obesity rates have tripled over the last 60 years. Severe obesity, also known as morbid obesity, has risen tenfold.

State data suggests that just over a third of Americans are currently obese. However, nationwide data shows that this could be an underestimation.

How is obesity measured?

A person’s weight class, which can range from underweight to obese, is determined by a screening tool referred to as the Body Mass Index (BMI). BMI is calculated by dividing someone’s weight (in kilograms or pounds) by their height (in meters or feet).

However, while BMI is a reasonable indicator of body fat for children and adults, it doesn’t distinguish between excess fat, muscle, or bone mass.

How have obesity rates changed over time?

In the early 1960s, roughly 13% of people were considered obese by Centers for Disease Control and Prevention (CDC) guidelines. Recent figures suggest that a current national obesity rate closer to 43%.

In addition, nearly 10% of all Americans were morbidly obese during the 2017–2018 survey, compared to less than 1% in 1960–1962. Childhood obesity rates tripled from 5% in the early 1970s to more than 19% by March 2020.

Obesity rates vary across different demographics and states and tend to be more prevalent among certain racial/ethnic groups and those in lower income brackets.

Which groups have higher obesity rates?

Obesity rates are uneven throughout America. According to data from the 2021 Behavioral Risk Factor Surveillance System (BRFSS), lower-income Americans tended to have higher obesity rates than high-income earners.^[1]

However, this trend is not clear-cut, as obesity rates can vary by income bracket and state.

For example, in Alabama, the obesity rate for people making between $100,000 to $199,999 was surveyed at 46.4%, compared to 37.5% for people making less than $15,000 a year.

Obesity rates in Alaska were highest among those making between $100,000 and $199,999 and highest in Oklahoma among those making more than $200,000.

Across all income brackets, those making between $15,000 and $24,999 had the highest surveyed obesity rates in 21 states and Washington DC, followed by those making between $25,000 and $34,999 in 11 states.

Rates were also higher among certain racial and ethnic groups. Of those surveyed, American Indian/Alaska Native, non-Hispanic people had the highest obesity rates in 18 states, while Black, non-Hispanic people the highest rates in 16 states.

Asian, non-Hispanic people had the lowest obesity rate of all groups surveyed across almost every state.^[2]

While the causes of differences between racial and ethnic groups are not known, the CDC suggests that underlying socioeconomic and environmental factors may help explain these disparities. These could include lower high school graduation rates, higher rates of unemployment, higher levels of food insecurity, and more.

Additionally, college or technical school graduates surveyed had lower obesity rates than people with lower educational attainment. However, obesity rates of people who didn't graduate high school, did graduate high school but not college, and or had some collegiate or technical schooling did not vary significantly.

It should be noted that observing these variables alone does not indicate that certain groups of people are inherently more likely to be obese than others. The causes of obesity are complex and multi-faceted. Genetic, environmental, and socioeconomic factors, among others, need to be considered before deeming that one group of people are prone to obesity.

Which states have the highest obesity rates?

According to 2021 BRFSS data, West Virginia had the nation's highest obesity rate: 40.7% of its population. This was followed by Alabama at 40.4% and Kentucky at 40.3%.

Colorado had the lowest rate at 25.0%, followed by Hawaii at 25.9%, and Massachusetts at 27.0%.

Obesity rates grew in every state between 2011 and 2021. South Dakota had the highest change, rising from 27.8% in 2011 to 38.6% in 2021, an overall increase of 10.8%. Kentucky followed at 10.2%, then New Mexico at 8.9%.

Regional obesity rates were highest in the South and lowest in the Northeast.^[3]

How does obesity impact overall health?

The National Cancer Institute says that obese Americans are more at risk for certain cancers, including pancreatic, liver, and thyroid cancers.

Obesity has been found to increase the risk of several other serious diseases and health conditions including type 2 diabetes and heart disease.

Adults with obesity also have triple the rate of hospitalization after a COVID-19 infection. Of the more than 900,000 COVID-19 hospitalizations from March 2020 until November that same year, an estimated 271,800 (30.2%) were attributed to obesity.

The CDC reports that the two primary drivers of mortality are smoking and obesity; the agency notes that while reductions in smoking is driving declines in mortality, the countervailing obesity trend is reversing those gains.

The rise in obesity affects American pocketbooks too. According to the CDC, obesity-related medical care costs the US healthcare system an estimated $173 billion a year.

Why do obesity rates vary by so much?

Data cited in this article are sourced from two regular surveys administered by the CDC: The Behavioral Risk Factor Surveillance System (BRFSS) and the National Health and Nutrition Examination Survey (NHANES).

Both surveys are nationally representative, but only the BRFSS collects data detailing state trends. BRFSS, started in 1984, is a telephone survey in which Americans are asked about various aspects of their health including their height and weight. NHANES, started in the early 1960s, is conducted by trained medical professionals directly collecting data about Americans.

For this reason, it is likely that BRFSS underestimates obesity since medical professionals are more likely to collect accurate data whereas people who may feel stigmatized about their weight status are more likely to underreport.

In 2018, BRFSS reported the national obesity rate for adults at 30.9% while the NHANES report from that same year cites a higher figure of 42.4%.

A note on BMI: Measurements relying on BMI may not accurately reflect the proportion of the population which is overweight or obese.

According to the CDC, BMI should not be used as a diagnostic tool for weight-related issues, and tends to oversimplify health risk. It also does not account for factors such as age, sex, and ethnicity.

Still, based on the available metrics we at USAFacts are comfortable using it to infer current obesity rates. While these may not completely represent the US population, it does reflect a general increase in obesity nationwide.

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