Overnutrition is a significant component of food waste and has a large environmental impact

Extent of overnutrition in Italy

The first result of this study is an estimation of the extent of overnutrition in Italy, based on national data about overweight conditions. Such estimation assumes that overnutrition is the additional caloric intake required to maintain an overweight / obese person in her di lei / his di lei current condition di lei. Overnutrition is thus evaluated as the difference between the calories ingested and the recommended calorie intake17 or, in other terms, the energy gap between the food consumed and the food required11.18. Such difference was estimated considering the body mass index of the overweight / obese people, broken down by gender and age classes, as well as different levels of physical activity for the different categories of individual (see “Methods” section for more detail).

Overall, we estimated that overnutrition accounts for 2.676 billion kcal per year for the Italian population, 64% of which is due to the increased caloric intake of overweight people. Significant territorial differences can be detected in this estimation with 32% of the total overnutrition occurring in the South of Italy, while North-West, North-East and the Center of the country account for 25%, 20% and 22% of the total , respectively.

Quantity of food corresponding to overnutrition

To estimate the quantity of food corresponding to the excess calories consumed by Italian overweight and obese people, we have pieced together the food categories — and the respective quantities — that make up a typical Italian diet.

Based on the third Italian National Food Consumption Survey (INRAN-SCAI 2005–2006, more info at www.crea.gov.it), the present study identified the main features of the typical Italian diet in 11 large categories and 46 subcategories of foods and beverages. Figure 1 shows the average daily food consumption by food category of adult males and females (18–64 years) in the four main geographical areas of Italy (North-West, North-East, Center and South-Islands). The same figure includes examples of standard portion sizes per food category, determined using the fourth edition of the LARN (Level Assumption Recommended Nutrients) for the Italian population19. They represent reasonable quantities of food, consistent with food tradition and consumer expectations, taken as reference units for both nutrition professionals and consumers. At first glance, the daily food consumption pattern is characterized by the highest contribution from cereals and cereal products, oils, and fats, followed by meat, vegetables, fruits, alcoholic beverages, and sweets. On the other hand, daily consumption of pulses, fish and eggs is substantially lower than the standard portions of 150 g fresh pulses, 150 g fresh fish and 50 g eggs, respectively. Food consumption data shows similar patterns among the four main macro-regions, which were otherwise characterized by a tendency towards a lower daily food consumption in the South-Islands area with some exceptions (ie, fish, eggs, oils, and fats). The caloric content of such diets is shown in Table 1, where the specific caloric content of each food included in the diet is used to calculate the total caloric content.

Figure 1
figure 1

Mean individual daily consumption by food category in male and female adults (18–64 years) in the four Italian macro-regions (INRAN-SCAI, 2005–2006). Numbers are expressed in grams per day. Red horizontal lines represent the standard portion sizes for each food category, expressed in grams per day.

Table 1 Caloric content of the typical Italian diet by macro-region. The table reports the weight of the typical diet expressed in grams per day, its caloric content expressed in kcal, and the conversion rate obtained by dividing the weight of the daily diet by its respective caloric content, expressed in grams per kcal.

The conversion rate between caloric content and quantity of food has been used to calculate the equivalent quantity of food corresponding to the excess calories intake consumed by Italian overweight and obese people. Such estimation is made for all the 46 food categories considered in the typical diet, summing up to 1.553 million tonnes of equivalent food over-consumed in Italy every year (Fig. 2). The food categories that are most represented (Fig. 3) are cereals, fruits, and vegetables, which together make up almost half of the total food over-consumed. No significant differences can be detected among the Italian macro-regions concerning the prevalence of such food categories in overnutrition.

Figure 2
figure 2

Quantity of equivalent food consumed in excess in Italy, in 1 year, due to overnutrition of overweight and obese people in Italy, by macro-region. Numbers are expressed in tonnes per year, and they refer to the whole population of each region. The total food consumed in excess adds up to 1.553 million tonnes of food in the whole country.

Figure 3
figure 3

Contribution of food categories to overnutrition of overweight and obese people in Italy. The Figure represents the percentage contribution of each food category to the total food consumed in excess in the whole country.

Environmental impact of overnutrition

The GHG emissions associated with overnutrition in Italy are calculated for each Italian macro-region, distinguishing between overweight and obese people, and splitting the environmental impacts among the supply chain stages of each foodstuff. In particular, the following stages are considered: production (including primary agricultural and fishery production), transformation (including food processing), packaging (including production of primary packaging and its end of life), transport (including raw material transport to processing plant or distribution center and transportation from processing place to distribution centers), distribution (including transportation from distribution centers to retailers and the storage at the distribution center and at the supermarket) and consumption (including the cooking phase of food). The GHG emissions considered for each stage are reported in the Supplementary Information.

The total GHG emissions of overnutrition in Italy are estimated at 6.15 Mt of CO2-eq per year (Table 2), which corresponds to an additional emission burden of about 24% and 12% for obese and overweight adults than normal-weight people, respectively. On average, each normal-weight person’s food-related emissions in 2018 were 1.75 t CO2-eq, with differences in the range of – 7.9% and + 5.4% among Italian macro-areas. This data is comparable with that reported by Crippa et al.7 who estimated 2.4 t CO2-eq in 2015 for the European region (but including GHG emissions associated with land use and land-use change activities). The results are also aligned with the value obtained by Battle-Bayer et al.20equal to 1.6 t CO2-eq per capita for an average Spanish adult citizen. However, comparisons among different studies are difficult mainly due to the differences in terms of functional units (mass-based or energy-based) and system boundaries.

Table 2 Total GHG emissions of overnutrition in Italy, broken down by food categories, and calculated for each macro-region and for Italy as a whole. All data is expressed in t CO2-eq per year.

With respect to the contribution of Italian macro-regions to the environmental burden due to overnutrition, it is interesting to highlight that the South-Islands is the macro-region with the largest impact (31.6%), followed by the North-West (26.6 %), the Center (22.2%), and the North-East (19.1%).

Figure 4 shows the contribution of the food categories to GHG emissions due to increased food intake. In all Italian macro-regions, the consumption of beef was responsible for the largest environmental impact of overnutrition, despite accounting for only 3.2% of the food weight at national level. Cheese, fresh fish, and other meats (rabbit and lamb) followed in terms of importance but with different contributions to the total GHG emissions. The most significant differences were related to South-Islands and North-East macro-regions, where fresh fish and other meats were the second-largest contributors, accounting for 10.2% and 7.5%, respectively. Overall, animal-based products were the largest contributors (meat: 55%; dairy products: 13%; and fish: 8%) to the environmental impact of the overnutrition in Italy, followed by fruits and vegetables (9%), cereal- based products (7%) and sweets (5%).

Figure 4
figure 4

Contribution of food categories to the GHG emissions of Italian macro-regions. The Figure represents the percentage contribution of each food category to the total GHG emissions of the food consumed in excess, in each macro-region of Italy.

In terms of life cycle processes, the primary production is the phase that has the largest impact on total GHG emissions (82.3%), followed by transportation (6.0%), packaging (4.8%), food processing stage (4.0%), preparation (eg, cooking, 1.9%), and distribution and retail (1.0%). It should be noted that the farming stage of beef production accounts for about 34% of total GHG emissions associated with Italian overnutrition. In the Agribalyse database, the production of beef was assumed to come 100% from France and the emission factor for the production stage was equal to 43.09 kg CO2-eq per kg of (boneless) cooked meat, corresponding to 14.32 kg CO2-eq per kg of live weight. To evaluate the reliability of this data for the calculation of GHG emissions due to beef consumption in Italy, the countries of origin and their contribution to the national supply of beef were considered. Basing on data provided by the FAO Food Balance Sheets21 and ISMEA22, it was determined that most of the beef consumed in Italy in 2018 was produced in Italy (61%), Poland (7%) and France (7%). Buratti et al.23 reported an environmental impact of 18.21 kg CO2-eq per kg of live weight in Italy, while Bieńkowski et al.24 estimated a value of 25.43 kg CO2-eq per kg of live weight in Poland, highlighting that the emission factor is acceptable even if slightly underestimated. Considering the emission factor for the beef production in Italy, the GHG emissions associated with the consumption of beef meat would increase from about 2.16 Mt of CO2-eq to 2.74 Mt of CO2-eq. Moreover, the total GHG emissions of overnutrition in Italy would reach the value of 6.72 Mt of CO2-eq, with an increase of about 10%.

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