Given the impact that our eating habits have on the health of both ourselves and the planet, it is remarkable how little attention it receives in the public discourse. Food is a very emotional topic for many of us. A part of our cultural or personal identity, its role is not simply to keep us from starving, but often to strengthen our connection with the people we love and hold dear. Who doesn’t have any fond memories of a traditional christmas dinner, thanksgiving potluck or summer picknick. But does this mean that we shouldn’t include it when looking for solutions to both the environmental crisis and the public health crisis? I don’t think so.
In this post, I want to give an overview of the shortcomings of our current diets and present the outline of a “planetary health diet”, that is, a diet that is good for both the human and the planet’s health. I will in a large part rely on the assessment of the latest scientific research on the topic by the EAT-Lancet Commission on healthy diets from sustainable food systems .
Let’s first start by talking about the environmental impact of our food, which is quite substantial. In fact, the food supply chain is responsible for more than 25% of global greenhouse gas emissions, uses up more than 35% of habitable land and more than about 65% of the world wide freshwater withdrawal .
In general, there are several ways in which food production has an impact on the environment, but I will here focus on greenhouse gas emissions, which are the main driver for climate change.
About one quarter of the global emissions are from food production, and we can further split that down by origin. An astonishing 30% of these emissions can be traced back to livestock and fish farms, with another 22% stemming from crop production for animal feed and land use for livestock. Land use accounts for the loss in CO2 absorption due to change in land use (e.g. cutting down forests to create pastures). On the other hand, crop production and land use for human food together only account for 29% of these emissions. This is quite impressive, considering that plant-based foods provide 82% of the global calorie supply and 63% of the global protein supply.
The differences between different foods are not just existing between plant-based and animal products, but also within these categories. For example, the greenhouse gas emissions for 100g of protein from beef (farmed for meat) is more than double than that of lamb and mutton, or beef from dairy herds. On the other hand, the emissions for tofu are only one twentieth of that of beef, but still five times as much as those of peas. The main point to take away however, is that even lower impact animal products are causing much more emissions than high impact plant-based products.
What can also be quite surprising, is that transport only accounts for about 6% of food related emissions. This is due to the fact, that most food is transported rather efficiently by ship and not by plane. This means, that while using local ingredients is never a bad idea, what you eat always has a larger impact on your environmental footprint than where your food comes from (as long as it doesn’t arrive by plane).
A final consideration should go to food waste. Even though this is not directly related to diet (except maybe for different shelf-lives), it is good to keep in mind, that about quarter of the greenhouse gas emissions from food are lost in food waste. This means that already without a diet change, there is a lot of potential for reducing our greenhouse gas emissions from food production .
From this data, it seems pretty obvious that the best way to reduce emissions from our food is to eat less animal products, while simultaneously reducing food waste. In the context of our general efforts to combat climate change, food is a great lever, since changes don’t require large technological advances or new infrastructure and can be made on a personal level (it is probably the single biggest change any person can make to reduce their carbon footprint). It also is a great way to buy ourselves some more time, since a large part of these emissions are not actually from CO2 but from methane, a much more powerful, but also rather shortlived greenhouse gas. A swift reduction in the global amount of livestock could lead to a significant drop in atmospheric concentrations of methane in as little as 15-20 years.
Concerning our health, it is commonly known that our western diets are much too high in processed foods and added sugars, which is a big contributor to rising numbers of obesity, diabetes and cardiovascular disease. But recent research suggests, that the high quantity of animal products is also contributing to the problem. Fruits and vegetables, which can counteract these effects, are on the other hand consumed far too little. There is even a bunch of research suggesting that plant-rich diets can help prevent and slow down cancer . Overall, the EAT-Lancet Commission estimates, that a change in eating habits could prevent up to 11 Million deaths from chronic diseases each year.
There are however also some more concerning public health issues created by the way our food (or livestock in particular) is “produced”. This point has again been getting more attention, due to COVID-19, a coronavirus that originated in animals and likely evolved to infect humans in the conditions of live animal markets. This is by no means the first time a dangerous virus has mutated in animals to then pass on to humans. In fact, several recent epidemics were caused in a similar way, such as SARS, the swine flu and the bird flu. Where large numbers of animals are kept in bad conditions, an animal-infecting virus can quickly spread and might mutate to a form, that can infect humans.
But we should keep in mind, that there is also a second problem with the way we currently raise livestock, which is the extensive use of antibiotics and other antimicrobials, both preemptively and as growth promoters. This has led to an increased resistance of diseases usually treated with that kind of medication, which makes it much harder to save humans that suffer from them. In fact, the WHO estimates that the antimicrobial resistance crisis is causing about 700’000 deaths each year .
The Planetary Health Diet
If you have followed the post so far, the solution is probably obvious. Reducing the amount of meat and animal products in our diets and replacing them with fruits, veggies and legumes will help us save the planet, while simultaneously allow us to live healthier lives. The EAT-commission recommends a flexitarian diet that still allows for modest amounts of meat, fish and other animal products, which they formulated in a very general way to make it easy to adapt. The main part (about 50% by volume) of such a diet should consist of fruits and vegetables, principle sources of proteins are legumes and nuts. Of course, this flexitarian diet should still avoid processed foods and added sugar where possible.
For those who do want to go the extra mile, the commission notes that further reducing animal products or going completely plant-based is easily possible while still getting all of your nutrients (the only exception being vitamin B12, which livestock usually also gets via supplements). The key here is to make sure you eat from a large variety of different foods and listen to your body.
If you want to learn more about the benefits of a largely plant-based diet, you can check out the summary report of the EAT-Lancet commission yourself. It is available in several languages and is not as difficult to understand as the main report. There have also been some very interesting documentaries recently that I can warmly recommend. Even though they focus on completely plant-based diets, many of the benefits they discussed can be gained at least partially from a flexitarian diet as well:
- Forks over Knives (2011)
- Cowspiracy (2014)
- What the Health (2017)
- The Game Changers (2018)
Finally, if you want to start implementing more plant foods in your diet, but don’t know where to start, here are a few great resources for delicious vegan and vegetarian recipes, that I use quite regularly myself:
I hope this article was able to demistify a little bit, what a healthy and sustainable diet can look like. Changing habits is always difficult and this also applies to eating habits. For some people, it might be easiest to radically change their diets in one go, but for others, approaching it slowly might make it easier to explore and get used to all the options available. Maybe you can start with a “Vegan Wednesday”, or by using soy milk in your cereals. And in this process, you might discover delicious things that you never tried before, which actually happened to me on my journey.
Stay safe, stay healthy, and bon appetit!
 W. Willett et al. (2019), Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems,
The Lancet, Volume 393, Issue 10170, https://www.thelancet.com/commissions/EAT (Summary: https://eatforum.org/eat-lancet-commission/eat-lancet-commission-summary-report/)
 J. Poore and T. Nemecek (2018), Reducing food’s environmental impacts through producers and consumers, Science, Volume 360, Issue 6392, https://science.sciencemag.org/content/360/6392/987/
 H. Ritchie (2020) – Environmental impacts of food production, https://ourworldindata.org/environmental-impacts-of-food [accessed: 09.01.2020]
 Mayo Clinic (2019), How plant-based food helps fight cancer, https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/how-plant-based-food-helps-fight-cancer/art-20457590 [accessed: 05.01.2021]
 World Health Organisation (2019), News Release: New report calls for urgent action to avert antimicrobial resistance crisis, https://www.who.int/news/item/29-04-2019-new-report-calls-for-urgent-action-to-avert-antimicrobial-resistance-crisis