A Correspondence letter published in The Lancet calls attention to the relationship between transportation and food. Dr. Phil Edwards and Dr. Ian Roberts (London School of Hygiene and Tropical Medicine, UK) claim that promoting healthy urban transport policies – walking and cycling, for example – would contribute to a decline in both the demand for world oil and the current insecurity of the global food chain. The greatest gains, they say, would not be through a general decline in car use, but through a reduction in the excess food and car use demands that come from the obese portion of the population.
“Motorised transport is more than 95% oil dependent and accounts for almost half of world oil use. Because oil is a key agricultural input, demand for transportation fuel affects food prices. Increased car use also contributes to rising food prices by promoting obesity, which, for the reasons outlined below, increases the global demand for food,” write the authors.
In order to maintain the basal metabolic rate (BMR), it is assumed that a population with a stable mean body-mass index (BMI) of 24.5 kg/m² consumes about 1550 calories of food per person per day (pppd). Energy for daily living activities requires an additional 950 calories pppd for a total of 2500 calories pppd. A population of obese people, with a stable mean BMI of 29.0 kg/m² needs 1680 calories pppd to maintain BMR and additional 1280 calories pppd for daily living activities, for a total of 2960 calories pppd activities of daily living. The obese population, therefore, requires more than 18% more food energy than a normal population.
It is also argued that since the mass of the obese population is greater than a normal population, more transportation fuel energy is required to transport the obese. This is only likely to worsen since obese people will choose to walk less and drive more in response to their increased body mass.
Reductions in obesity and transportation oil demand can be achieved by implementing policies that promote walking and cycling, according to the authors. A reduction in obesity prevalence should correspond with a reduction in the global food and energy demands.
“Decreased car use would reduce greenhouse gas emissions and thus the need for biofuels, and increased physical activity levels would reduce injury risk and air pollution, improving population health,” conclude the authors.
Transport policy is food policy
P Edwards, I Roberts
The Lancet(2008). 371[9625]: p. 1661.
Written by: Peter M Crosta