Understanding that we prioritise protein is also important when considering the environmental impacts of the diets that we eat.
High protein foods are associated with high greenhouse gas emissions, so you might assume that we should be reducing the density of protein in our diets in order to also reduce our greenhouse gas emissions.
But this assumes that our energy intake remains constant as the proportion of protein in our diet decreases, which we know is not true.
It is our protein intake which remains more constant, so as we dilute the proportion of protein in our diet our energy intake increases.
If we reanalyse the data in those terms we find that reducing protein in the diet will reduce greenhouse gas emissions, but only if high protein foods are replaced by real plant-derived foods, such as vegetables, grains, fruit and pulses.
If high protein foods are replaced by ultra processed foods, environmental damage is not reduced, and can even be worse.
One reason for this is the energy used in the industrial production of ultra processed foods. Another reason is their low protein content leads to overconsumption — and the production of each additional calorie eaten produces greenhouse gases.
Real foods that are low in protein, such as vegetables and grains, are not overeaten in the same way, because they contain gut-filling fibre.
So ultra processed foods are low in protein, high in energy, and damaging to the environment.
And there’s another problem — their nutrient density is at an absolute rock bottom, whereas it’s diets rich in wholefoods that peak in these health-giving substances.
Why then do we tolerate diets that are unhealthy and unsustainable?
Nobody really wants the planet to be poisoned. Nobody wants our bodies to be poisoned. Yet both outcomes are so persistent within our food system.
This is because they are deeply bedded within the economic system that governs all of this, such that there are market benefits to the economy of having ultra processed foods consumed at the high levels they are.
Market benefits are, of course, good for the country — but at what cost to public and planetary health?
The key challenge then is to manage the drivers of our food system in such a way that the economic, health and environmental benefits are better balanced.
Policy tools are available for this, and are already being implemented in some countries. These include health taxes (based for example on the amount of added sugar), front of package warning labels, restrictions on marketing and distribution, and media campaigns.
No one of these will on its own address the problem. They need to be interlinked in sets of reinforcing strategies, as is being done in Chile and Brazil.
Such tools are no stranger to Australia. They have been used to good effect to reduce tobacco, and to some extent, alcohol consumption.
Similar measures applied to food will help reduce the burden of preventable disease and save the natural world on which we rely for producing food.
Including those species, such as insects and apes, that have helped us understand how we have gone wrong and where we can do better.