Abstract
The environmental impacts of food systems and the health consequences of excess food intake are well-acknowledged global issues. However, the climate impact of excess food intake, or metabolic food waste, has received less attention. This study estimated the amount of metabolic food waste and its climate impact in Sweden. Excess food intake was estimated based on the adult overweight and obesity prevalence in Sweden, by applying two alternative calculation methods, one based on the energy content of excess body fat, and the other based on the excess energy intake due to excess body fat. These caloric values were translated to food consumption patterns according to three dietary scenarios and their climate impact estimated based on carbon footprint data. The results showed that the annual amount of metabolic food waste represented 480–710 kt of food in Sweden and, regardless of dietary scenario, exceeded the annual amount of avoidable household food waste. The estimated greenhouse gas emissions from the metabolic food waste amounted up to 1.2 Mt CO2e annually, accounting for approximately 2% of the total and 10% of the food-related climate impact in Sweden. This study confirms the magnitude of the hidden climate cost of excess food intake on a national level and emphasizes the importance of taking this aspect into consideration in actions to improve both planetary and human health. Although applied to the Swedish context, the methodology used in the present study could also be used to assess the environmental impact of excess food intake in other countries globally.
Highlights
Modern food systems are largely unsustainable, posing a threat to global food security, partly because of the high environmental impact of food production and consumption
Calculations of excess body fat Calculations of excess body fat were conducted for each body mass index (BMI) group (normal weight (NW), OW, and OB), for females and males, respectively, prior to averaging them, according to the following steps and based on the assumption that energy balance existed in the whole population: 1) Average body weight was calculated based on average BMI and average height as an inverse function of BMI as: average body weight = midpoint of BMI cut off
The results indicated that the annual amount of metabolic food waste exceeds the total annual amount of avoidable household food waste by up to 66%, representing a significant amount of food waste among the Swedish adult population due to excess food intake (Swedish Environmental Protection Agency, 2020)
Summary
Modern food systems are largely unsustainable, posing a threat to global food security, partly because of the high environmental impact of food production and consumption. Industrialized food systems account for 19–29% of the total global anthropogenic greenhouse gas emissions (GHGEs), making them a major contributor to climate change, the defining challenge of our time (Vermeulen et al, 2012). Another aspect of the unsustainability of food systems is food loss and food waste generated throughout the supply chain from agricultural production to household consumption. While the global food and grocery retail market was valued at US$11.7 trillion in 2019, the costs related to global food wastage were estimated to reach US$2.6 trillion annually with economic, environmental, and social costs included (FAO, 2014; GVR, 2020a). While food waste treatment facilities are a necessity, investments in such infrastructure could entail lock-in effects leading to an unwillingness to reduce food waste
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