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.
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: Peter M Crosta