Greater Social Disadvantage Linked to Higher Obesity Risk in Nationally Representative U.S. Study

A new study in Obesity, the flagship journal of The Obesity Society, puts a number on something clinicians have long suspected: the more social disadvantage a person carries, the more likely that person is to have obesity. The researchers found the pattern held even after accounting for clinical and demographic factors, and they describe their work as the first to test the idea in a nationally representative sample of U.S. adults.

The data came from nearly 165,000 adults aged 18 or older who took part in the National Health Interview Survey between 2013 and 2017. The survey is a cross-sectional household questionnaire run every year by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention. Overweight was defined as a body mass index of 25 to under 30, and obesity as a BMI of 30 or higher. The team split obesity further into class 1 and 2 (BMI from 30 up to 40) and class 3 (BMI of 40 or above).

Previous research, the authors explain, had linked individual factors such as education, income, neighborhood and food environment to obesity. What had not been done was to look at the combined weight of those factors. To do that, the team adapted a framework from the Kaiser Family Foundation and sorted social determinants of health into six domains: economic stability; neighborhood, physical environment and social cohesion; community and social context; food; education; and the health care system. In all, 38 measures were combined into a single cumulative score, which was then divided into four quartiles representing rising levels of burden.

The researchers compared overweight and obesity across those quartiles for the population as a whole and by age, sex and race and ethnicity, using multinomial logistic regression adjusted for relevant covariates. Obesity prevalence climbed in steps as social burden increased. At nearly every quartile, middle-aged adults and non-Hispanic Black adults had higher rates of overweight and obesity than their White counterparts, and the study also noted differences by sex.

In the fully adjusted models, adults in the fourth quartile, the heaviest burden, had a 15% higher relative prevalence of overweight than those in the first quartile. For obesity class 1 and 2 the figure was 50%, and for class 3 it was 70%.

Khurram Nasir, MD, MPH, MSc, of the Division of Cardiovascular Prevention and Wellness at Houston Methodist DeBakey Heart and Vascular Center in Texas, is the study's corresponding author. He argued that current cardiovascular care models generally give clinicians no way to assess a patient's social burden in a holistic way, which compromises quality of care and worsens health inequities. He called on providers and policymakers to build new care delivery models that assess these factors, to prioritize socially vulnerable populations in cardiovascular prevention programs, and to form partnerships between health systems and community stakeholders, backed by strong political will.

The authors acknowledge what the study cannot yet show. They say future work should use longitudinal designs, build data platforms that let self-reported and medically confirmed information be cross-checked, and model the combined effect of multiple social factors with additional methods such as machine-learning algorithms.

Fatima Cody Stanford, MD, MPH, MPA, MBA, an obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School, was not involved in the research. She is The Obesity Society's councilor for advocacy, public affairs and regulatory matters. She said the findings support addressing equity and access to social determinants if obesity, which she called a complex, multi-factorial disease, is to be improved in the United States and worldwide.