Food and life cycle energy inputs: consequences of diet and ways to increase efficiency

Food consumption is one of the most polluting everyday activities when impacts during product life cycles are considered. Greenhouse gas emissions from the food sector are substantial and need to be lowered to stabilise climate change. Here, we present an inventory of life cycle energy inputs for 150 food items available in Sweden and discuss how energy efficient meals and diets can be composed. Energy inputs in food life cycles vary from 2 to 220 MJ per kg due to a multitude of factors related to animal or vegetable origin, degree of processing, choice of processing and preparation technology and transportation distance. Daily total life cycle energy inputs for diets with a similar dietary energy consumed by one person can vary by a factor of four, from 13 to 51 MJ. Current Swedish food consumption patterns result in life cycle energy inputs ranging from 6900 to 21,000 MJ per person and year. Choice of ingredients and gender differences in food consumption patterns explain the differences. Up to a third of the total energy inputs is related to snacks, sweets and drinks, items with little nutritional value. It is possible to compose a diet compatible with goals for energy efficiency and equal global partition of energy resources. However, such a diet is far from the Swedish average and not in line with current trends.