Dr Gary Whitlock and colleagues studied people who had been seriously injured or killed between 1988 and 1998 while driving a motor vehicle. The subjects were categorised into four groups according to their Body Mass Index (that is their 'weight for height').
The most obese drivers were found to have been twice as likely to experience injury over the study period than people of average size. This may be due to the fact that overweight people are more likely to suffer from sleeping disorders(such as sleep apnoea which causes a cessation of breathing while asleep, making it difficult to sleep for long periods) and therefore may be more likely to fall asleep at the wheel.
The thinnest people were also more likely to have had an injury compared to those in the middle weight range, which may be due to the higher risk of bone fractures in thinner people.
Seatbelts are designed for average-sized people so this may also be a factor.
Dr Whitlock undertook this research during the tenure of a Health Research Council of New Zealand training fellowship at the University of Auckland, working with colleagues at the universities of Auckland, Sydney and Oxford.
Paper: Gary Whitlock, Robyn Norton, Taane Clark, Rodney Jackson and Stephen MacMahon. 'Is body mass index a risk factor for motor vehicle driver injury? A cohort study with prospective and retrospective outcomes', IJE 2003, Vol 32, No 1 pp147-149
The International Journal of Epidemiology is a key journal in the field of epidemiology and public health, published six times per year by Oxford University Press. It is edited at the Department of Social Medicine, University of Bristol, which is a leading centre for epidemiology, health services research and public health in the UK and was one of only three to be awarded the top 5* grade in the 2001 Research Assessment Exercise.