Background Obesity is a growing health issue in the United States (US) known to contribute to chronic diseases and injuries. We wondered whether recent obesity trends might be large enough to be visible amongst drivers involved in fatal crashes in the US. Objective: To assess obesity trends in drivers involved in fatal crashes in the United States.

Methods The Fatality Accident Reporting System database of the National Highway Traffic Safety Administration was analysed to assess drivers’ obesity trends. All drivers involved in a fatal crash from Jan 1999 to Dec 2012 with reported height and weight were included in the analysis. Vehicle occupants and pedestrians were excluded from the analysis because of lack of information. Drivers’ obesity was defined by body mass index according to the World Health Organisation definitions of under or normal weight, over-weight, and obesity class I-III.

Results Of 753,024 drivers involved in fatal crashes from 1999–2012, BMI was available for 534,719 drivers. Overall, 36% were over-weight, 14% had obesity class I, 4% had obesity class II, and 2% had obesity class III. The prevalence of overweight in drivers rose from 34% in 1999 to 36% from 1999 to 2012. Over the same period, the prevalence of class I obesity rose from 12% to 16%, class II obesity from 3% to 6%, and class III obesity from 1% to 3%. Trends remained significant (P < 0.001) after adjusting for vehicle and drivers characteristics. Surprisingly, fewer obese drivers tested positive for alcohol compared to non-obese drivers (16% vs. 23%, P < 0.001). Conclusions: We suggest that the increasing population prevalence of obesity in the US is sufficiently large to contribute to increasing numbers of fatal motor vehicle crashes.