ImportanceAdherence to a healthy lifestyle is associated with lower risks of adverse outcomes. However, trends in multiple lifestyle factors and overall healthy lifestyle status among US adults in recent years are unknown.ObjectiveTo examine trends in multiple lifestyle factors and overall healthy lifestyle among US adults.Design, Setting, and ParticipantsThis serial cross-sectional study used nationally representative data from 10 National Health and Nutrition Examination Survey (NHANES) cycles (nine 2-year cycles from 1999 to 2016 and 1 combined cycle from 2017 to March 2020) among adults 20 years or older. Data were analyzed from December 10, 2021, to January 11, 2023.ExposureSurvey cycle.Main Outcomes and MeasuresFive healthy lifestyle factors: never smoking, moderate or lighter alcohol consumption (for women: ≤7 drinks/wk; for men: ≤14 drinks/wk), healthy diet (Healthy Eating Index–2015 scores ≥60.0), sufficient physical activity (≥150 min/wk of equivalent moderate physical activity), and healthy weight (body mass index [calculated as weight in kilograms divided by height in meters squared] 18.5-24.9).ResultsA total of 47 852 adults were included in this study. The weighted mean [SE] age was 47.3 [0.2] years; 24 539 (weighted proportion, 51.5%) were women. From the 1999-2000 cycle to the 2017 to March 2020 cycle, the estimated prevalence of the 5 lifestyle factors showed divergent trends, with increasing prevalence of never smoking (from 49.4% [95% CI, 46.4%-52.4%] to 57.7% [95% CI, 55.5%-59.9%]; difference, 8.2% [95% CI, 4.5%-12.0%]), healthy diet (from 19.3% [95% CI, 16.0%-22.6%] to 24.5% [95% CI, 21.5%-27.5%]; difference, 5.2% [95% CI, 0.8%-9.7%]), and sufficient physical activity (from 55.7% [95% CI, 51.8%-59.6%] to 69.1% [95% CI, 67.2%-71.1%]; difference, 13.4% [95% CI, 9.0%-17.8%]), while prevalence of healthy weight decreased from 33.1% (95% CI, 30.5%-35.6%) to 24.6% (95% CI, 22.6%-26.7%; difference, −8.4% [95% CI, −11.8% to −5.1%]) (all P < .001 for trend). Meanwhile, there was no significant trend in moderate or lighter alcohol consumption. Overall, the estimated prevalence of at least 4 healthy lifestyle factors increased from 15.7% (95% CI, 12.8%-18.7%) to 20.3% (95% CI, 17.8%-22.7%; difference, 4.5% [95% CI, 0.7%-8.4%]; P < .001 for trend). Disparities in healthy lifestyle were widened by age group, with little improvement among adults 65 years and older (difference, 0.04% [95% CI, −4.28% to 4.35%]). There were persistent disparities in healthy lifestyle by race and ethnicity, educational level, and income level.Conclusions and RelevanceThe findings of this cross-sectional study of NHANES data over a 22-year period suggest diverse change patterns across 5 healthy lifestyle factors and a modest improvement in overall lifestyle existed among US adults, with worsening or persistent disparities in lifestyle.