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Sustainable Diets 101

The idea of sustainable diets has been around for some time, but what exactly are they? The Food and Agriculture Organization (FAO) defines sustainable diets as having the following features:1

  • Low environmental impact,
  • Protective of biodiversity and ecosystems,
  • Culturally acceptable,
  • Economically fair and affordable,
  • Accessible,
  • Nutritionally adequate,
  • Healthy,
  • Safe.

Given the FAO definition, it is clear that the environment is only one of many factors to be considered. In addition, most studies measure the environmental impact of diets using only greenhouse gas emissions (GHGE) as a marker of climate change. However, other factors need to be considered: land use, water footprint, energy and use of fossil fuels.

In fact, a systematic review published in 2015 concluded that there is a “need for a far more complete assessment of the environmental, social, and economic impacts of foods and diets.”2 

What is the impact of food systems on the environment? 

Food systems, including the whole supply chain from the farm to the consumer’s plate, account for:

  • About 30% of the world’s energy consumption;
  • Just over 20% of total GHGE.3

Several studies indicate that there are environmental benefits to increasing the consumption of fruits and vegetables, while reducing the consumption of animal-based foods.4,5 However, there is growing evidence that a diet high in fruits and vegetables and low in meat may not have a lower environmental impact. This is due to the higher amount of plant-based substitutes that need to be consumed to replace animal proteins and calories.3,6 Furthermore, fruits and vegetables grown in greenhouses generate more GHGE than animal-based foods.7

Environmentally friendly diets need to be healthy

While the environment is an important aspect of a sustainable diet, the latter also needs to be nutritionally adequate. Yet, an environmentally friendly diet is not necessarily healthy, and vice versa. For example, while a decrease in the consumption of animal-based foods is suggested to be beneficial for the environment, meeting nutritional requirements with a strict plant-based diet may nevertheless be more difficult.3

For more information, read Are plant-based diets necessarily more sustainable

Overconsumption and food waste

When talking about sustainability, overconsumption of food and food waste also need to be considered.

  • Eating too much food has a negative effect on both the environment and human health. Overconsumption places a higher demand on food production, resulting in higher GHGE;8
  • Food waste across the entire food supply chain has been estimated to be 10% to 40%.5 And in developed countries, food waste at the retail and consumer levels needs to be addressed.9


  1. Food and Agriculture Organization of the United Nations. Sustainable diets and biodiversity: directions and solutions for policy, research and action. Rome, Italy: FAO and Bioversity International. 2012.
  2. Auestad N and Fulgoni VL III. What current literature tells us about sustainable diets: emerging research linking dietary patterns, environmental sustainability, and economics. Adv Nutr 2015;6:19-36.
  3. Food and Agriculture Organization of the United Nations. 2011. Energy-smart food for people and climate. Rome, Italy. 2011.
  4. Reynolds CJ et al. Are the dietary guidelines for meat, fat, fruit and vegetable consumption appropriate for environmental sustainability? A review of the literature. Nutrients 2014;6:2251-2265.
  5. Hallström E et al. Environmental impact of dietary change: a systematic review. J Clean Prod 2015;91:1-11.
  6. Vieux F et al. Greenhouse gas emissions of self-selected individual diets in France: changing the diet structure or consuming less? Ecol Econ 2012;75:91-101.
  7. Clonan A and Holdsworth M. The challenges of eating a healthy and sustainable diet. Am J Clin Nutr 2012;96:459-460.
  8. Macdiarmid JI. Is a healthy diet an environmentally sustainable diet? Proc Nutr Soc 2013;72:13-20.
  9. Reisch L et al. Sustainable food consumption: an overview of contemporary issues and policies. SSPP 2013;9:7-25.

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