A method was developed for designing ‘fair’ diets (not using more than globally available arable land per
capita) and for assessing the sustainability of such diets. The diets were based on the principle of ‘ecological
leftovers’ for livestock production, i.e. raising livestock on pasture and by-products not suitable for or
wanted by humans. The method was applied to Sweden using three different scenarios for livestock
production, all taking the starting point that semi-natural pastures should be grazed by ruminants for
reasons of biodiversity conservation. The scenarios also included differing use of by-products (from crop
production and food processing) to either boost milk production (I-Milk scenario) or produce eggs and pig
meat (E-Milk and Suckler scenarios). In I-Milk, milk and meat were produced in intensive systems in
which dairy cows and their offspring only grazed to a limited extent, resulting in the human diet containing
recommended levels of dairy products (350 ml milk per day) and meat twice a week. Milk could also
be exported. In E-Milk, pasture was used more for dairy cows and their offspring, resulting in fewer
animals and less milk (150 ml milk per day) and four servings of meat per week. In the Suckler scenario,
pasture was grazed by suckler herds providing no milk but meat four times per week. The environmental
impacts of the diets were assessed using the planetary boundaries framework. The results showed substantially
lower environmental impacts compared with the average current Swedish diet, but the strict
absolute climate boundary and the N and P input boundaries were still exceeded for all diets. The
approach adopted, of letting the ecological resource capacity act as the constraining factor for livestock
production, is in line with agroecology principles and efficient use of land to improve food security,
and could be useful in discussions about sustainable consumption of animal products.