Abstract
Our food choices, food production pathways and household behaviors together govern the impact that our diet has on our health as well as the environment. As the planetary population grows, there is an increasing awareness of the need to both improve the quality of our diets for health reasons and to reduce its impact on the earth. From the consumer perspective, however, it is not always clear which healthy diet options and behaviours contribute most to reductions in our dietary footprint. In this paper we model and contrast the impact of the current American diet and three recommended diets from the USDA Dietary Guidelines 2015-2020 on six dimensions of the dietary footprint: land area required, blue water use, fertilizer application, primary energy input, ammonia emissions and greenhouse gas emissions based on LCIA studies. For each diet we test the relative impacts of a shift in diet composition, caloric intake and the reduction in food waste on the dietary footprint. We find that there are multiple pathways to significantly reduce the environmental impact of our diets. Shifts in diet composition from the current diet to a vegetarian diet had the greatest impact on reducing the dietary footprint, however, combinations of reducing caloric intake from 2600kcal/d to 2000kcal/d combined with 50% reduction in food loss could achieve similar results in some cases. In line with results of other studies, we find that reducing red-meat and dairy contribute most to the dietary footprint. However, recommended increases in fruits and vegetables with dietary shifts are accompanied by significant increases in blue water use. We extrapolate our estimated of environmental impacts out to 2051 when the US population is set to reach 400 million people. By combining a number of incremental shifts in diet composition, intake level, and food loss, significant land currently under production could be spared from production for other uses while still providing a nutritious diet for all.
Highlights
What we eat and how we produce it define our most fundamental relationship with the planet
To help inform consumer decision, in this article we explore the relative environmental impacts of (i) a shift in diet composition toward more plant-based foods, (ii) a shift in caloric intake from 2,000, 2,600, to 3,200 kcal/d, and (iii) a reduction in food waste by 10, 25, and 50% on resource demands of three diets outlined in the 2015–2020 Dietary Guidelines for Americans (USDHHS and USDA, 2015) as compared to the current American diet
This study aims to provide information to consumers on the relative impact that changes in diet composition, caloric intake, and food waste behaviors can have on their dietary footprint
Summary
What we eat and how we produce it define our most fundamental relationship with the planet. Over the past 200 years, farming has become the most influential driver of land use change (Ramankutty and Foley, 1999; Steffen et al, 2015). Today 37% of the terrestrial surface of the planet and over two thirds of our freshwater resources are dedicated to producing food (Foley et al, 2005; Pretty et al, 2006; Dobermann and Nelson, 2013; HLPE, 2013). The twin drivers of population growth and increasing per-capita food consumption have, and continue, to fuel food demand and land use change (Tilman et al, 2001). With the global population projected to reach, and possibly exceed 9 billion by 2050 (United Nations DESA, 2017), new modalities of production and consumption are necessary to nourish the planet
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