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While the USDA recommends eating more fruits and
vegetables, produce typically requires not only the
greatest energy use per calorie to get to our tables,
but also relatively high GHG emissions and water
withdrawals to grow, irrigate and harvest. So, while
cantaloupe, for example, might be better for our
waistlines, potato chips are better for the
environment.
Amidst the current
overweight and obesity epidemic in the USA, the
Dietary Guidelines provide food and beverage
recommendations that are intended to help
individuals achieve and maintain healthy weight.
From growing, processing
and transporting food, to food sales and service,
and, finally, to household storage and use, feeding
a nation unavoidably takes a toll on our resources
in the form of energy use, water withdrawals and
greenhouse gas (GHG) emissions.
So could eating
healthier not only benefit us, but also the
environment? The answer, Tom found, is complicated.
On the one hand, results
show that eating fewer calories, as recommended by
the 2010 USDA dietary guidelines, could reduce
energy use, water withdrawals and GHG emissions from
within the food supply chain by around 9%.
Yet, following
guidelines on calories and on the USDA recommended
mix of fruit, vegetables, dairy, seafood, and other
food groups leads to a different result.
In this case, by eating healthier as a nation, we
would likely increase our environmental impact
across all three categories measured in her
research.
How so? There’s a complex relationship between diet
and the environment. Largely though, you can blame
the fruits and vegetables.
The three dietary
scenarios researchers examine include (1) reducing
Caloric intake levels to achieve “normal” weight
without shifting food mix, (2) switching current
food mix to USDA recommended food patterns, without
reducing Caloric intake, and (3) reducing Caloric
intake levels and shifting current food mix to USDA
recommended food patterns, which support healthy
weight.
This study finds that
shifting from the current US diet to dietary
Scenario 1 decreases energy use, blue water
footprint, and GHG emissions by around 9 %, while
shifting to dietary Scenario 2 increases energy use
by 43 %, blue water footprint by 16 %, and GHG
emissions by 11 %. Shifting to dietary Scenario 3,
which accounts for both reduced Caloric intake and a
shift to the USDA recommended food mix, increases
energy use by 38 %, blue water footprint by 10 %,
and GHG emissions by 6 %.
These perhaps
counterintuitive results are primarily due to USDA
recommendations for greater Caloric intake of fruits,
vegetables, dairy, and fish/seafood, which have
relatively high resource use and emissions per
Calorie.
For more information
Energy use, blue water footprint, and greenhouse gas
emissions for current food consumption patterns and
dietary recommendations in the US
Link...
Carnegie Mellon
University
Civil and Environmental Engineering
Weighing Environmental Impacts of Obesity in US
Population
Link...
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