top of page

Adopting an environmentally sustainable diet

Dernière mise à jour : 3 mars 2022

After a year of trying to cut out mos meats from my diet, I took part in a Climate Fresk ("Fresque du Climat") and discovered that going from pescetarianism to veganism would be greatly beneficial for my carbon footprint. Since I am an unconditional lover of cheese and sushi, and since I had no idea what a vegan diet looked like, I tested veganism for a few months, to see if my health (through a blood test) or my lifestyle (financially, mentally or socially speaking) would really change.

"New York city has no power

And the milk is getting sour;

But to me it is not scary,

Cause I stay away from dairy."

- Phoebe Buffay

My only concern for more than a year was the industry's GHG emissions, but here are now the main reasons I have for keeping up with a mostly plant-based diet now that my test is over (most of them I develop in the rest of the articles, but this is a sum-up if you don't have time for the whole thing):

  • Everyone adopting a mostly plant-based diet is not an option when it comes to sustainability - not only because it accounts for more GHG than all transports, but also in terms of water consumption and deforestation. It's one of the easiest and most efficient climate actions one can take - and it doesn't require as much effort as one can think.

  • Cattle is the main driver of deforestation - of the Amazon, for example. Interestingly, one of the other main drivers of deforestation is soy... a cereal that's massively produced for cattle. Industries behind this deforestation are linked to the killings of hundreds of people trying to defend the forests each year.

  • Vegan people get the same nutrients as meat eaters, as long as they learn about food variety. Meat (especially high intakes several times a week) is not necessary for a balanced diet.

  • Behind every animal killed, there is a human being that nurses, and sometimes bonds with a living animal.

  • And maybe the most important: just because one doubts an argument or finds a slight loophole doesn't invalidate scientific truths. For example, pointing out that Novak Djokovic doesn't call himself a vegan (an argument repeated many times against the Game Changers movie, for example) doesn't undermine the fact that people with a mostly plant-based diet can have amazing performances in sports.


It's a long article, so here's a summary of the sections :


A little context: why agriculture is an environmentally important and urgent matter

Our food production (and therefore, consumption) impacts our environment from several angles, and some dietary decisions can help reduce our environmental impact:

  • GHG emissions. In 2018, agriculture amounted for 26% of the emissions that cause global warming: not only CO2 (carbon dioxyde), but also CH4 (methane) and N2O (nitrous oxyde). They come from machinery, fertilizers, transports, enteric fermentation, etc. Beef is the most important source of emissions, particularly because of the digestive process of cows: enteric fermentation emits a lot of methane, which traps a lot more radiations than carbon dioxide. Lamb & mutton comes close, cheese & dairy follow, and so on. Plant-based foods, on the other hand, have a much lower impact on emissions.

  • The use and contamination of land and water. Half of habitable surface on Earth is used for agriculture, and it is not because we need this much to grow enough food to survive. Moreover, producing 100 grams of beef-based protein uses more than 160 meters square, whereas it only takes 2.2 meters square to produce 100 grams of tofu-based protein. A vegan - or almost vegan - global diet means that 3 billion hectares could be freed up for, say, reforestation or natural wildlife habitats. This freed up land could also be beneficial for implementing strategies to convert intensive to more environment-friendly and humane farming.

  • The modification of biomass. Livestock accounts for 60% of mammals... and humans for 34%: wild mammals only represents 4% of the biomass of mammals on our planets. The same goes with birds: poultry represents a great majority (approximately 70%) of birds. Besides its intrinsic and cultural values, biodiversity has a great importance for maintaining our ecosystem.

How to reduce my impact ? In terms of GHG emissions, the first instinct of many is to eat locally. I agree that eating locally, you might have a better contact with farmers, support them, and know, for example, if their farm is intensive and respect the animals. However, it has quite a low impact on your carbon footprint. Indeed, it only affects the supply chain portion of emissions, which, for meat, is very small. Substituting some or all of your meat consumption with plant-based products will considerably reduce your environmental impact, and could encourage your friends and family to adopt a more plant-based diet as well. This is a first - necessary - step towards the voluntary adoption of a sustainable global diet.

Do I risk nutritional deficiencies?

Disclaimer: the following content is there to gather scientific, journalistic and governmental information, but it's only a blog; I'm not a nutritionist or a medical doctor, so, in doubt, check with one!

There are usually three nutritional concerns brought up by non-vegans, when it comes to reducing one's meat consumption : protein, iron, B12... I believe the reason is that we are never taught the difference between plant-based and animal nutrients. Instead, we are taught that only meat and dairy have them, and that plants, while healthier, are optional (spoiler, it's actually the opposite). I took this shortcut for most of my life as well, and I realised how little I knew about it when I started reading about vegetarian and vegan nutrition. So here are the main things I learnt while studying the matter.

  • Getting good quality plant-based protein is not more complicated than getting animal protein. The only thing that matters is to eat various foods and take in enough calories - which is basically what we should do, even for meat-eaters. This could resemble a diet with a lot of cereals and legumes instead of animal products, for example. This would nullify the controversy about the quality of plant-based proteins: plants, when taken one by one, can have very little of 1 or 2 out of the 12 amino acids we need, but odds are you can eat more than one type of plant. If you're not comfortable with it, or are used to never eating legumes (for example), you can try protein combining or this adorable Harvard Healthy Plate Explorer to understand plant diversity better.

  • Iron and B12 (cobalamin). The concern about these two nutrients is often the risk of anemia. Plant-based (non-heme) iron is abundant in many foods, like lentils, beans or tofu. Vitamin C (spinach, tomato, pepper, fruits, and so on) is supposed to help absorbing non-heme iron. B12, on the other hand, is created by bacteria and often found in soil; cattle animals get it from either grazing or taking supplements. Vegans usually take either nutritional yeast or supplements for B12 directly, which is highly sufficient. Personally, my blood test done months after becoming a vegan doesn't show any anomaly compared to when I became a pescetarian.

  • A rarer concern, but it interested me : fatty acids. When I started my vegan diet, someone told me they encountered problems when they cut out meat, because they were lacking fats. This might be because many cut out meat without having a clear representation of how they can get essential fats like omegas. In general, plant-based fats are healthier than animal fats, but they might come from foods that (like legumes), we're less used to eating. I found very little information about this problem and am not a nutritionist, but I thought it would be useful to indicate the reason I included fats in my mindmap below.

Generally speaking, eat less to no meat has been shown on multiple occasions to decrease the chance of multiple diseases; however, we tend to focus on these issues, that, on the contrary, have often been proven overestimated. Of course, if you are still not sure about it or already suffer from nutritional deficiencies or are not used to balancing your diet, switching to a vegetarian diet first or asking advice to your medical doctor when switching to a completely vegan diet is more cautious.

Information that lobbies won't teach us: my mindmap of vegan nutrition

Most nutritional and culinary informational we are taught concern meat and dairy, and we are almost never taught how to eat well with a plant-based diet. This is mainly because the industrial lobbies of meat and dairy are extremely powerful and because their environmental impact have been completely silenced until recently. Several examples in the US for example, show the conflicts between experts (of health and environment) and meat lobbyists. The most famous example occurred in 1977, when lobbyists demanded that the dietary recommendations wouldn't advise people to "decrease" their consumption of meat. This has created, in the last decades, a culture of meat and of disliking plants that experts struggle to deconstruct.

I believe that flexitarianism and pescetarianism (the diet I adopted for a year) are quite popular these days because they allow us to reduce our environmental impact and avoid dissonance between our education and our diet. The media is a great representative of this dissonance: according to a study of The Daily Mail, article offering incomplete "reassuring" arguments in favour of animal products often accompany articles proving their potential hazard for health. For example, limiting your meat, fish, eggs or dairy intake to once or twice a week is already progress, and it is more than enough for average needs. Transitioning to a mostly vegan diet can be smoother that way, since it allows us to test out which changes we want for us.

Apart from cognitive dissonance, another obstacle often implicitly prevents us from modifying our diet: the myth that we're "eliminating" meat instead of "substituting" plants to it. Many don't associate "cutting out meat" with "eating more plants", which can lead to all of those beliefs about deficiencies or those oh-you're-a-vegan-so-you-only-eat-salad reaction. There are several reasons why "eating enough, and diversified enough...but in vegan" is counter-intuitive for us. I personally have learned that "eating various foods" meant eating meat, dairy, fish, eggs, fruits, vegetables and starchy foods. When you take out the four first components, you're left with something that doesn't quite represent all the variety of foods you can/should eat. Hard to do a shopping list with no clue what it could look like ! So here's a quick (simplified) mind map of my version of variety. It includes animal products so as to better represent the transition.

A feedback on my own experience: rowing against the norm

My main observations after trying to remove animal products from my diet for several months:

1. Most obstacles to vegan diets are societal: it's actually really easy to eat vegan at home

However, eating out, with friends or by ourselves, is not that easy: in France - let alone in Spain, where I also lived - most restaurants don't even bother offering a vegan option. And where there is one, sometimes there is no protein source in it (it's just a few grams of veggies, for the same price). The same goes with precooked meals. Even grocery shopping becomes difficult if you're strictly vegan, and also avoid products with traces of fish, eggs or dairy. I did this for the first few months, but it's impossible to follow through in restaurants that aren't strictly vegan. Did you know that vegetable soups sometimes weren't vegan ?!

Financially speaking, it doesn't get much more difficult. I didn't spend a lot more than when I was a pescetarian...except for when I was stuck at the university with no cheap (and good) vegan option inside the neighborhood. You can circumvent this pretty easily if you like to cook and have the time to prepare your lunch the day before. However, that was not my case. This is the main reason I went back to being a vegetarian, so that I could allow dairy when I "had" to. Generally, a vegan diet would logically be a lot less expensive than the other ones.

The only hickup, as an environmentalist (and a lazy person) is that I really hate buying plastic-wrapped vegan patties and sausages - another wonderful cognitive dissonance that you can circumvent by cooking.

2. Not being a strict "vegetarian" or "vegan" doesn't keep you from reducing your intake of animal products to your own minimum.

Cultural education shouldn't be an obstacle to respecting the environment. What's more, trying to be vegetarian or vegan and making an exception at a punctual moment shouldn't be seen as a failure. You can design your own "rules of food": I decided on mine after the few months of veganism test. Testing is important: after a few months, I knew the two or three foods that I had missed - the ones I ate even during my vegan challenge, and felt guilty afterwards -, and the ones I really didn't want to eat anymore. Time also counts: it is also possible to also do vegan months several times a year. However you do it, all of these possibilities can help you have your "customised" plant-based food intake.

3. There is still a lot of stigma and close mindedness on other people's diets, as well as paradoxal social value associated to the activity of eating meat.

"Yuck, vegan steak?",, "I could never not eat meat", "So chicken and rice for us, and uh...just rice for you", "You're still in your vegan madness/phase ?", "Oh ok you're that kind of an environmentalist", "I'm not eating at this restaurant if I can't eat meat".

What the hell? Somehow not eating meat was either an insult or an exceptional accomplishment, as if people were allergic to plants. I had to consider myself lucky when no one told me to "make an exception" or that I was annoying. I sometimes felt like the simple act of eating meat was considered a social activity and was said to have values, whereas eating plants, somehow, was wrong. I believe this is still due to our education and the influence of meat and dairy lobbies. Lots of indicators show that this is absurd: to me, the fact that we should pay extra for a lentils and quinoa pattie instead of a steak would mean that either the vegan food is overpriced for marketing reasons, either the meat is of extremely bad quality...


The studies about the consequences of climate change (as well as land and water use) and the necessary solutions to it bring to light that adopting a worldwide mostly plant-based diet is not an option. The budget of 2 tons of CO2 equivalent per person in France is a clear enough indicator that meat and dairy aren't sustainable foods, since an omnivorous diet would already take up at least half of it. Switching to a plant-based diet would help improve our impact, eat healthier, and make demand grow towards a more vegetal and - maybe - respectful and extensive agriculture.

I experienced a vegan diet for a few months, before going back to a vegetarian diet and writing this article. As a sports enthusiast and a person who never takes more than 30 minutes to cook anything, I wanted to see if it was as hard as people - even people from my sustainability classes - thought. Spoiler alert: it's not... as long as you're informed.

My goal, while writing the article, was to hand over the main information needed to switch to a plant-based diet, as well as to reflect on why many of us stigmatise this choice and feel like it's impossible to go vegan. Since our bodies and minds can very well make due without any animal products, it would seem that the biggest obstacle to a vegan diet - and the one preventing me from being exclusively vegan now - is the difficulty that arises from our society: lobbies pushing stigma and meat-based education and the lack of plant-based products displayed to us are two examples.

Final note: as always, I welcome any constructive feedback; however I have had 5 months to observe the reactions readers could have when hearing about any new nutritional information, so make sure to be respectful of my work before sending your remarks!



  1. Hannah Ritchie and Max Roser (2021) - "Forests and Deforestation". Published online at Page "Drivers of Deforestation" Retrieved from:, [Online Resource]

  2. Hannah Ritchie and Max Roser (2021) - "Forests and Deforestation". Published online at Page "Soy" Retrieved from:, [Online Resource]

  3. United States Department of Agriculture (2015) - "USDA Coexistence Factsheet Soybeans". Publisehed online at Retrieved from: [Online Resource]

  4. What are the biggest drivers of tropical deforestation ? They may not be what you think. (2018), World Wildife Magazine, Issue of Summer 2018. Retrieved from:

  5. 1540 land and environmental defenders were killed between 2012 and 2020,,

  6. Moens, Jonathan (2020). Why Eating Local Isn't Always Best For The Environment. Published in Retrieved from: [Online Resource]

  7. Cho Renee (2012). How green is local food. Retrieved from:

  8. FAO (2020). Emissions due to agriculture. Global, regional and country trends 2000-2018. FAOSTAT Analytical Brief Series No 18. Rome.

  9. Hannah Ritchie and Max Roser (2020) - "Environmental Impacts of Food Production". Published online at Retrieved from: [Online Resource]

  10. Chakir, R., Cara, S. D., & Vermont, B. (2011). Émissions de gaz à effet de serre dues à l’agriculture et aux usages des sols en France: une analyse spatiale. Economie et statistique, 444(1), 201-221

  11. Yinon M. Bar-On, Rob Phillips, Ron Milo (Jun 2018). The biomass distribution on Earth. Proceedings of the National Academy of Sciences Jun 2018, 115 (25) 6506-6511; DOI: 10.1073/pnas.1711842115

  12. Overview of Greenhouse Gases.

  13. Rosane Olivia (2018). Humans and Big Ag Livestock Now Account for 96 Percent of Mammal Biomass. Published Online at Retrieved from:

  14. Quel est l'impact de notre alimentation sur l'environnement ? (2021).

  15. Hobert Ryan, Negra Christine (2020). Climate Change and the future of food. Published Online at Retrieved from:

  16. Vetter David (2021) How Much Does Our Food Contribute To Global Warming? New Research Reveals All. Published Online at Retrieved from:

  17. Harvey Fiona (2019). Can we ditch intensive farming - and still feed the world? Published Online at Retrieved from:

  18. Lohbeck, M., Bongers, F., Martinez-Ramos, M. and Poorter, L. (2016), The importance of biodiversity and dominance for multiple ecosystem functions in a human-modified tropical landscape. Ecology, 97: 2772-2779.

  19. Katcher H, I, Ferdowsian H, R, Hoover V, J, Cohen J, L, Barnard N, D: A Worksite Vegan Nutrition Program Is Well-Accepted and Improves Health-Related Quality of Life and Work Productivity. Ann Nutr Metab 2010;56:245-252. doi: 10.1159/000288281

  20. Varner, G. E. (1994). In defense of the vegan ideal: Rhetoric and bias in the nutrition literature. Journal of Agricultural and Environmental Ethics, 7(1), 29-40.

  21. Katharina C. Wirnitzer, Chapter 21 - Vegan Nutrition: Latest Boom in Health and Exercise, Editor(s): Alexandru Mihai Grumezescu, Alina Maria Holban, Therapeutic, Probiotic, and Unconventional Foods, Academic Press, 2018, Pages 387-453, ISBN 9780128146255, (

  22. V R Young, P L Pellett, Plant proteins in relation to human protein and amino acid nutrition, The American Journal of Clinical Nutrition, Volume 59, Issue 5, May 1994, Pages 1203S–1212S,

  23. Lim JJ (2021). Plant Protein Combinations That Boost Protein Quality. Published Online at Retrieved from:

  24. Mariotti F, Gardner CD. Dietary Protein and Amino Acids in Vegetarian Diets-A Review. Nutrients. 2019;11(11):2661. Published 2019 Nov 4. doi:10.3390/nu11112661

  25. Healthy Eating Plate,,

  26. Iron,,

  27. Vitamin C,,

  28. Iron, B12 and more: a guide for vegans,,

  29. Pawlak, R., Berger, J., & Hines, I. (2016). Iron Status of Vegetarian Adults: A Review of Literature. American journal of lifestyle medicine, 12(6), 486–498.

  30. Cobalt deficiency in sheep and cattle (2019),,

  31. Rizzo, G., Laganà, A. S., Rapisarda, A. M., La Ferrera, G. M., Buscema, M., Rossetti, P., Nigro, A., Muscia, V., Valenti, G., Sapia, F., Sarpietro, G., Zigarelli, M., & Vitale, S. G. (2016). Vitamin B12 among Vegetarians: Status, Assessment and Supplementation. Nutrients, 8(12), 767.

  32. Ducharme, J (2018). Plant Fats Are Healthier Than Animal Fats, Study Says. Published Online at Retrieved from:

  33. Fats and omegas,,

  34. Nestle M. Food Lobbies, the Food Pyramid, and U.S. Nutrition Policy. International Journal of Health Services. 1993;23(3):483-496. doi:10.2190/32F2-2PFB-MEG7-8HPU

  35. Shanker Deena (2015). The US meat industry's wildly successful, 40-year crusade to keep its hold on the American diet. Published Online at Retrieved from:

  36. Frédéric Leroy, Malaika Brengman, Wouter Ryckbosch, Peter Scholliers, Meat in the post-truth era: Mass media discourses on health and disease in the attention economy, Appetite, Volume 125, 2018, Pages 345-355, ISSN 0195-6663,

  37. Graves, C., & Roelich, K. (2021). Psychological Barriers to Pro-Environmental Behaviour Change: A Review of Meat Consumption Behaviours. Sustainability, 13(21), 11582.


Follow @msoryae on Instagram to be informed of new articles!

bottom of page