AbstractObjective: This study investigated differences in the use of health care services and associated costs between obese and nonobese patients.Research Methods and Procedures: New adult patients (N = 509) were randomly assigned to primary care physicians at a university medical center. Their use of medical services and related charges was monitored for 1 year. Data collected included sociodemographics, self‐reported health status using the Medical Outcomes Study Short Form‐36, evaluation for depression using the Beck Depression Index, and measured height and weight to calculate BMI.Results: Obese patients included a significantly higher percentage of women and had higher mean age, lower mean education, lower mean health status, and higher mean Beck Depression Index scores. Obese patients had a significantly higher mean number of visits to both primary care (p = 0.0005) and specialty care clinics (p = 0.0006), and a higher mean number of diagnostic services (p < 0.0001). Obese patients also had significantly higher primary care (p = 0.0058), specialty clinic (p = 0.0062), emergency department (p = 0.0484), hospitalization (p = 0.0485), diagnostic services (p = 0.0021), and total charges (p = 0.0033). Controlling for health status, depression, age, education, income, and sex, obesity was significantly related to the use of primary care (p = 0.0364) and diagnostic services (p = 0.0075). There was no statistically significant relationship between obesity and medical expenditures in any of the five categories or for total charges.Discussion: Obesity is a chronic condition requiring long‐term management, with an emphasis on prevention. If this critical health issue is not appropriately addressed, the prevalence of obesity and obesity‐related diseases will continue to grow, resulting in escalating use of health care services.