Nutrition: Principles Before Position

By Dr Sam Manger

Part 3: We can no longer ignore the externalities of our food choices

“The modern food consumer is confronted with two major challenges: to eat well for themselves and to eat well for the planet. To not achieve both will eventually mean to not achieve either.”

 – Dr Sam Manger

Will it be possible to feed a global population of 10 billion a healthy diet within safe planetary boundaries? This is a pertinent question of ever-growing concern that forces us to look beyond our own individual health to the health of the global ecosystem which supports life on Earth.

In the specific context of health and true cost economics, food manufacturers are allowed to sell a product, for which they bear the costs of production, distribution and marketing. They do not, however, have to cover the costs inherent in the impact of that product, such as health or environmental impacts, i.e. negative externalities. For example, while the specific economic burden of disease related directly to soft drink consumption is unknown, the negative health outcomes of its consumption, including cardiovascular disease and diabetes, cause significant healthcare costs in Australia. The total annual cost of type 2 diabetes in Australia is $6 billion annually (1), while CVD costs $7.7 billion annually (2). Much of these costs can be attributed directly to obesity, which is promoted – in part – by the over consumption of sugar-sweetened beverages.

In addition to the staggering healthcare costs, the processing, manufacturing, distribution and disposal of soft drink cans and bottles uses huge amounts of energy and water, whilst generating greenhouse gas emissions, not to mention the sheer volume of plastic that ends up in waterways throughout the country (and world).

If these costs were to be taken into account, these businesses may be wiped out: a United Nations report concluded that if the biggest global corporations paid for the true cost of the businesses – that is, they were made to pay for their negative externalities – then none of them would be profitable, and if they were unable to dodge their tax bills then they may even operate at a loss (3). It is no surprise, then, that they seek to influence public policy in the manner described earlier.

The environmental impact of food extends beyond just soft drink and junk food: between 20 and 40% of fruits and vegetables are rejected before they even reach the supermarket shelves, largely because they do not meet the supermarket’s cosmetic standards. Further, Australians discard at least 20% of the food they purchase – 4 million tonnes of food every year – which accounts for 12% of our individual emissions annually (4).

Worryingly, while some healthy diets (such as the Mediterranean diet) rightly encourage the consumption of some fish and seafood for health reasons, almost 80% of the world’s fisheries are either fully exploited, over-exploited, depleted, or in a state of collapse (5). Large-scale international research implores us to reduce our intake of red and processed meats and increase our consumption of plant foods, both for our health and the planet’s (6). This becomes worrying, however, when we consider that the majority of the world’s population resides in developing countries, whose meat intake is increasing at a staggering rate as they rise from poverty and become more affluent (7).

The detailed University of Oxford Grazed and Confused report concludes that, ‘ultimately, if high consuming individuals and countries want to do something positive for the climate, maintaining their current consumption levels but simply switching to grass-fed beef is not a solution. Eating less meat, of all types, is… Grazing livestock are net contributors to the climate problem, as are all livestock’ (8).

In contrast, the UK Sustainable Food Trust critiques the University of Oxford Grazed and Confused report as incomplete and encourages a balanced approach, integrating regenerative and grazing crop rotation livestock as a central part of sustainable food production, whilst at the same time acknowledging that ‘the increasing global demand for meat will result in serious and potentially irreversible consequences for the environment, because it will require large areas of virgin land to be converted to grain production’ and ‘consumers should be encouraged to reduce their consumption of intensively (e.g. confined animal feeding operations (CAFOs)) produced pork, poultry and beef reared on low forage/high grain diets’ (9).

The reason more grain-fed livestock means more grains/monocultures/deforestation is that a significant amount of human-edible grain is grown for livestock feed and hence converted to a lower yield of animal product (the feed conversion ratio, FCR).  Studies vary in their estimates here, from 1 kg of meat requiring 2.8kg of human-edible feed, up to 1kg of meat requiring 10kg of grain, despite the same studies indicating that 60-86% of the global livestock feed intake in dry matter consists of feed materials that are not currently edible for humans (10). Some studies estimate that global human calorie availability could be increased by as much as 70% by shifting crops away from animal feed and biofuels to human consumption (11), but again this is argued by some proponents of meat consumption as part of a balanced diet (12).

Overall, this is not dissimilar to the EAT-Lancet report that indicated that food production is responsible for up to 30% of global greenhouse gas emissions and 70% of freshwater use. Foods sourced from animals, especially red meat and grain-fed livestock, have relatively high environmental footprints per serving compared to other food groups, increasing greenhouse gas emissions, land use and biodiversity loss (13). Replacing 100% of beef intake with poultry could reduce mean dietary greenhouse gas emissions by 35.7%; when replacing all beef, pork, or poultry intake with plant-protein foods, the greenhouse gas emissions decreased by 49.6%, mean Healthy Eating Index increased by 8.7%, and dietary costs decreased by 10.5% (14). However, the EAT-Lancet Commission also recommends sourcing meat from farmers that practice regenerative agriculture which contributes to carbon storage in the soil, keeps water away from pollutants, and provides room for local biodiversity to flourish whilst at the same time producing higher-quality produce. To be clear though, permaculture and regenerative agriculture practices, like agroforestry, do not always require livestock.

The difficulty with this is that regenerative agriculture and permaculture sources of meat can be more expensive and are difficult to find, with 95-99% of chickens and pigs being factory-farmed or intensively raised (15), though this figure is significantly less for beef and lamb in Australia. There are also edible feral animals like rabbits, deer, camels and pigs that are ecologically destructive, but whilst these products are available at specialist butchers, they are also not easy to obtain en masse.

Overall, considering the vested interests from individuals, the meat and livestock industry and the grain industry, it can be very hard to get an unbiased picture of the best way to eat for both environment and health.  Both industries directly or indirectly produce evidence to support their interests and both, in my limited opinion, have agendas almost definitely of profit and control of food systems, economies and policy (and not public health). As US politician Henry Kissinger said: “Who controls the food supply controls the people; who controls the energy can control whole continents; who controls money can control the world.”

So, my fallible and not 100% confident interpretation of the reoccurring themes from all the sources (including meat and vegan proponents) I have reviewed is as follows:

  • We must massively reduce food waste, processed food production and intensive farming practices, such as confined animal feeding operations and intensive grain monocultures.
  • We must significantly increase our consumption of whole, fresh food and regenerative farming produce, support local and organic small scale farms where possible (though even these points are not entirely agreed upon).
  • The produce from regenerative agriculture should be predominantly plants but can include regenerative and grazing crop-rotated livestock, especially from land not suitable for crops.
  • Supporting reforestation and biodiversity programs is also key to the environmental sustainability of food.

From here it is easy enough to then practice whichever diet best suits an individual’s bio-psycho-socio-cultural-spiritual needs (see part 1), whether that be vegan, vegetarian, Mediterranean, pegan, paleo, low-carb or ketogenic. In fact, it is likely that two dinner plates from any of these diets would look remarkably similar: 50% or so above-ground plants, and 50% of whole, healthy forms of plant OR animal proteins, fats and/or whole starches and grains, all sourced from regenerative farming practices.

Thus, the modern food consumer is confronted with two major challenges: to eat well for themselves and to eat well for the planet. To not achieve both will eventually mean to not achieve either.

If you are interested in pursuing any of the ideas outlined above, my podcast with Joel Salatin explores this topic in depth. The Plant Proof Podcast with Simon Hill also investigates many of these topics.

#97 Farms, Food and Health with Joel Salatin

Apple Podcasts | SpotifyShow Notes

Plant Proof Podcast with Simon Hill

Apple Podcasts | Spotify


  1. Shaw, J., Tanamas, S.. (2012). Diabetes: the silent pandemic and its impact on Australia. Canberra: Diabetes Australia.
  2. National Heart Foundation of Australia (2012). Cost-effective actions to tackle the biggest killer of men and women: Heart Disease. Canberra: National Heart Foundation of Australia
  3. Trucost (2013). Natural capital at risk: the top 100 externalities of business. London: Trucost
  4. Food Waste Fast Facts [Internet]. Foodwise. 2020 [cited 7 May 2020]. Available from:
  5. Food and Agricultural Organization (2011). Review of the state of world marine fishery resources. Rome: FAO
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  8. Food Climate Research Network (2017). Grazed and Confused? Oxford: Food Climate Research Network
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  13. EAT (2019). EAT-Lancet Commission brief for Farmers. Stockholm: EAT
  14. Willits-Smith A, Aranda R, Heller M, Rose D. Addressing the carbon footprint, healthfulness, and costs of self-selected diets in the USA: a population-based cross-sectional study. The Lancet Planetary Health. 2020;4(3):e98-e106.
  15. ABC News. Factory farming masks meat’s tree costs. [Internet]. 2013 [cited 11 January 2021];. Available from: