Eating patterns (or diets) are an important point of interconnection in food systems between human health and wider environmental impacts. Shifts in how people consume towards sustainable health eating patterns can bring multiple benefits. And when they are undertaken by whole populations, their overall effects can be considerable. Although there is much we still don’t know, the broad trends of what sustainable health eating patterns look like are known well enough to take action today. However, this presents another difficult challenge: how can eating patterns (at the individual and population scale) be shifted towards those that are healthier and more sustainable? Understanding this problem and its potential solutions provides a useful primer on the way in which consumption in food systems takes place through a combination of human choices (whether conscious or not), and is influenced by the wider contextual environment that actively constrains and influences these choices.

The environmental and nutritional attributes of different food types can vary greatly. Consequently, diets composed of different sets of food types, will differ in their environmental footprints, and in their nutritional quality; so affecting human health. When such differences are multiplied by many millions of people, the overall effect is considerable. Human diets are, therefore, an important point of interconnection in food systems via which change is driven – for better or worse – by shifts how people consume. At least in theory, diets might provide a means by which to achieve both health and environmental goals simultaneously. But the reality is not so simple. Understanding these complexities, helps provide a window on both the opportunities and difficulties of taking a food systems approach, and on the important role that diets play.