Around the world, thousands of people are signing up for the Veggie Challenge and committing to a flexitarian, vegetarian, or fully plant-based diet for 30 days. Everyone has their own reasons – some people want to improve their health, while others are motivated to reduce their environmental impact or spare the lives of animals. In this article, we give you an idea of the resource savings you can expect to achieve by changing your diet for 30 days. This version of the article shows impacts for the UK.
Animals
Reducing or eliminating animal-based products – such as meat, dairy, and eggs – from your diet can help to lower the demand for these products. This, in turn, can prevent suffering and spare the lives of animals. See the table below to get a rough idea of how many animal deaths you have avoided by changing your diet.1
Going vegan for 30 days: ±2.08 animals2
Going vegetarian for 30 days: ±1.93 animals
You can read more about how we calculate the number of land animals in this article.
In addition to land animals, numerous fish will also be saved if seafood is part of your usual diet. It’s difficult to estimate the numbers here, since the quantity of fish is often measured in kilograms and tons rather than as individuals. What is certain, however, is that the number of fish and other marine life that have to die to satisfy the global demand for seafood far exceeds the number of land animals killed.
Environmental impacts
At ProVeg, we want to clearly and accurately show the environmental impact of your food choices, relevant to your country and based on credible science.
More information
We decided to base our impact calculations on the World Wildlife Fund’s Planet-Based Diets initiative1.
This ambitious project uses comprehensive data to estimate how shifts towards more plant-based diets can reduce environmental pressure – including greenhouse gas emissions, land use, and water use – for nearly every country in the world.
Many of the studies that look at the impact of diet changes tend to focus either on global averages or on a single country. Moreover, most studies are centred around western diets. When trying to engage people from many different parts of the world, we needed a dataset that reflects national dietary patterns and environmental footprints, while also being comparable between different countries.
The WWF’s Planet-Based Diets project does just that. Their methodology incorporates national-level dietary data from the Food and Agriculture Organization, along with detailed environmental footprints of different food groups. It provides estimates for how shifting to plant-based, vegetarian, or flexitarian diets in your own country affects environmental outcomes2. This makes the data much more relatable and accurate for participants around the world.
1 WWF: The impacts in each country. Available at:
https://planetbaseddiets.panda.org/national-impacts
2 WWF (2020): Bending the Curve: The Restorative Power of Planet-Based Diets. Available at:
https://wwfint.awsassets.panda.org/downloads/bending-the-curve—the-restorative-power-of-planet-based-diets-full-report.pdf
Based on the yearly impacts of current diets and plant-based diets, we calculated potential savings over a period of 30 days.
Going vegan for 30 days: 142.77 kg CO2 (or driving about 815 miles)
Going vegetarian for 30 days: 126 kg lbs CO2 (or driving about 718 miles)
Going Flexitarian for 30 days: 102.16 kg CO2 (or driving about 582 miles)
CO2
Eating less meat is one of the most effective ways to lower your carbon footprint. The livestock industry alone is responsible for up to 20% of global greenhouse gas emissions3. By reducing your consumption of animal-based products for just one month, you can significantly decrease your personal impact4 5 6 7. Many different studies have shown the resource savings from reducing your meat consumption – take a look at FoodSystemData for a full overview.
It can be difficult to understand what a kilogram of CO2 equivalent really means. For context, we’ve used the assumption that new passenger cars in the EU emit an average of about 109 grams CO2 per kilometer8.
Going vegan for 30 days: 142.77 kg CO2 (or driving about 815 miles)
Going vegetarian for 30 days: 126 kg lbs CO2 (or driving about 718 miles)
Going Flexitarian for 30 days: 102.16 kg CO2 (or driving about 582 miles)
Depending on what you eat, where you live, and where your food comes from, the potential savings might be higher or lower.
WATER
Globally, about 70% of the water that humans consume is used in the agricultural sector9. Because it takes much more water to produce animal-based products than it does to produce plant-based foods such as beans and whole grains, reducing your intake of animal-based products can have a substantial impact on the demand for water in food-producing regions.
Plants need water to grow, and meat production requires that animals eat a lot of plants. There are different approaches to water use, including water footprints, fresh-water usage, and scarcity-weighted water footprints (you can learn more about these approaches here). Studies have shown10 that plant-based foods and plant-based diets generally require less total water11.
See the table below for the water savings you potentially could make by signing up for the Veggie Challenge12:
Going Flexitarian for 30 days: 13,233 liters
Going vegetarian for 30 days: 9,041 liters
Going vegan for 30 days: 7,315 liters
LAND
A plant-based diet also means that a lot less land is used to produce the food you eat, including the land that would have been used to grow feed crops for animals. Much of the deforestation in South America, for example, is due to soya crops that are grown to feed livestock – in total, 75% of global soya production is used to feed animals, not humans13. Overall, animal-based foods use about 80% of global agricultural land, while only providing 17% of global calories and 37% of global protein.
Going vegan for 30 days: about 376.85 m2
Going vegetarian for 30 days: about 339.45 m2
Going Flexitarian for 30 days: about 300.82 m2
For more information on the Veggie Challenge, visit: https://veggiechallenge.net/
Disclaimer:
The impact numbers provided via the Veggie Challenge are for educational purposes only and are only indicative. The actual impact and potential reduction may vary, depending on the specifics of individual diets. These impact numbers are provided ‘as is’ without any warranties, either express or implied.
References
- Effectively, you will reduce the demand for animal products, so it’s future lives that you’ll save.
- The figures include direct consumption of land animals and fish. Figures for land animals were obtained using production and consumption data from The Food and Agricultural Organization of the United Nations: Food and Agriculture Organization of the United Nations (2025): Livestock primary. FAOSTAT Database. Rome, Italy. Available at: http://www.fao.org/faostat/en/#data/QL and Food and Agriculture Organization of the United Nations (2025): New Food Balances. FAOSTAT Database. Rome, Italy. Available at: http://www.fao.org/faostat/en/#data/FBS.
- Xu, X., P. Sharma, S. Shu, et al. (2021): Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods. Nature Food 2(9), 724–732. doi:10.1038/s43016-021-00358-x
- E. Hallstrom, A. Carlsson-Kanyama, P. Borjesson. (2015). Environmental impact of dietary change: a systematic review. Journal of Cleaner Production 91 1-11.
- Scarborough, P., P. N. Appleby, A. Mizdrak, et al. (2014): Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK. Climatic Change 125(2), 179–192. doi:10.1007/s10584-014-1169-1
- Abejón, R., L. Batlle-Bayer, J. Laso, et al. (2020): Multi-Objective Optimization of Nutritional, Environmental and Economic Aspects of Diets Applied to the Spanish Context. Foods 9(11), Multidisciplinary Digital Publishing Institute, 1677. doi:10.3390/foods9111677
- Springmann, M., L. Spajic, M. A. Clark, et al. (2020): The healthiness and sustainability of national and global food based dietary guidelines: modelling study. BMJ m2322. doi:10.1136/bmj.m2322 doi:10.1136/bmj.m2322
- European Environment Agency (2024): CO2 emissions performance of new passenger cars in Europe. Available at: https://www.eea.europa.eu/en/analysis/indicators/co2-performance-of-new-passenger
- WWAP (2017): The United Nations World Water Development Report 2017. Wastewater: The Untapped Resource. UNESCO, Paris.
- ProVeg International (2025): Water use. Available at: https://proveg.org/fsd-article/water-use/
- For example:
- Poore, J. & T. Nemecek (2018): Reducing food’s environmental impacts through producers and consumers. Science 360(6392), 987–992. doi:10.1126/science.aaq0216
- Scarborough, P., M. Clark, L. Cobiac, et al. (2023): Vegans, vegetarians, fish-eaters and meat-eaters in the UK show discrepant environmental impacts. Nature Food doi:10.1038/s43016-023-00795-w doi:10.1038/s43016-023-00795-w
- Vanham, D., S. Comero, B. M. Gawlik, et al. (2018): The water footprint of different diets within European sub-national geographical entities. Nature Sustainability 1(9), 518–525. doi:10.1038/s41893-018-0133-x
- Harris, F., C. Moss, E. J. M. Joy, et al. (2019): The Water Footprint of Diets: A Global Systematic Review and Meta-analysis. Advances in Nutrition doi:10.1093/advances/nmz091 doi:10.1093/advances/nmz091
- A.Y. Hoekstra (2015). The Water Footprint: The Relation Between Human Consumption and Water Use. The Water We Eat, Springer Water, pp 35-48. Calculated from table 2 (page 44).
And more
- A.Y. Hoekstra (2015). The Water Footprint: The Relation Between Human Consumption and Water Use. The Water We Eat, Springer Water, pp 35-48. Calculated from table 2 (page 44). Unfortunately they did not calculate savings for a vegan diet. If we assume that all consumed calories come from plant-based foods the number might be as high as 57.000 liters for a vegan diet.
- FCRN (2020): Soy: food, feed, and land use change. Available at: https://tabledebates.org/building-blocks/soy-food-feed-and-land-use-change [Accessed 04.03.2021]
