Universiteit Leiden

nl en

How the eating habits of a limited group of Americans determine sustainability

Masses of hamburgers, steaks, cheese and a lot of eggs: Americans love their animal products. But researcher Oliver Taherzadeh discovered that only a relatively small group of high-volume consumers need to modify their diet to achieve an enormous environmental gain.

The day on which we have used up all the biological resources that the Earth can regenerate in a year, Earth Overshoot Day, was this year 28 July. For the Dutch, this would be 12 April, and for Americans 13 March. Americans have the biggest ecological footprint in terms of food consumption; if they were to consume more plant-based products and fewer animal products, the impact on the environment could be reduced considerably. Taherzadeh is an Assistant Professor at the Institute of Environmental Sciences; he researched the impact American households could achieve by changing their eating habits.  

Moving smartly to a sustainable diet

‘I looked at a representative group of over 7,000 Americans and what they eat on a daily basis, and assessed the environmental outcome of their transitioning to the EAT-Lancet diet,’ Taherzadeh explains. The focus in this diet is primarily on plant-based food, and low intake of animal products, especially dairy and red meat.’

‘We modelled realistic dietary changes in the scenarios, assuming people who eat a lot of meat would reduce their meat consumption in moderation. I also calculated the environmental impact of the different meals and the individual raw ingredients they contain. If you eat a peperoni pizza, you are consuming a particular amount of pork, but then there’s also the tomatoes in the sauce, and wheat in the pastry. Each of these products has a different ecological footprint.’ 

The EAT-Lancet diet

The study looked at a partial transition to the EAT-Lancet diet. This diet, compiled by 37 independent international scientists, not only contains a lot of plant-based foods, but also leaves room for animal products. The diet was proposed to make it possible for all 10 billion people to be able to eat healthily and sustainably by 2050.

A remarkable finding from the study is that not all Americans need to change their diet to yield large reductions in the climate and land impacts of the US food systemThe environmental gains from adoption of the EAT-Lancet diet by the top 20% of high-impact consumers are far greater than the gains made from the same dietary shift across the remaining 80% of the population. The greenhouse gas and the land footprint of the US food system could be more than halved by this group switching in part to the EAT-Lancet diet.

Eating habits

Contrary to what people may think, there is a considerable variation in eating habits within the US. Taherzadeh: ‘In many cases, we look at a national average eating patterns when formulating policies for sustainable eating habits. But this doesn’t take into account the enormous differences between the eating habits of individuals and groups within countries. These unique eating patterns become visible when you distinguish between different income groups, genders and ethnic backgrounds. I created profiles for the impact of different groups by looking at the individual members of households and what they eat. This will help policymakers encourage behavioural change where it is most needed.’

‘By introducing targeted measures, not to blame people but to encourage them to change their behaviour, we can reduce the impact of food on the environment.

Encouraging behavioural change

Taherzadeh believes that the real task now is in the hands of governments and markets. ‘We can’t blame individuals. People are often locked into particular patterns of consumption because of inequality, such as lack of time, money or education.’

‘By introducing targeted measures, not to blame people but to encourage them to change their behaviour, we can reduce the impact of food on the environment. As an example, an effective measure in restaurants is to highlight sustainable choices and make them cheaper. A meat tax would also be a good option. Where possible, we should look at subsidising greener alternatives so that consumers aren’t penalised for making sustainable choices.’ 

Dutch diet

Although he only studied eating habits in the US, Taherzadeh expects that the study's findings could also apply to the Dutch food system. ‘Even within the Netherlands there are enormous differences in terms of eating habits, so I would expect to see the same trend. The Dutch diet isn’t unsustainable, but it does contain a lot of meat and dairy produce. Targeted policy measures aimed at consumers could have a big impact.’ 

What can you do?

You can make an impact today by changing your diet. Oliver Taherzadeh has some tips for how you can do that relatively easily.

‘Do you eat meat and/or dairy produce every day? If so, try eating a plant-based diet on weekdays. If you do that, you’ll be reducing your consumption of animal products by 70%. Even substituting animal and plant-based proteins can reduce the ecological footprint of your diet considerably.’

‘Have you already switched to a – partly – plant-based diet yourself?  If so, you can try encouraging others to do the same, via your social networks, at work and by joining social movements that campaign for policy change.’ 

‘You can also become a prosumer and take the food system into your own hands. Try growing food in your garden or on your balcony. If you don’t have a garden or balcony, you can think about renting an allotment (there are over 240,000 of them in the Netherlands) or joining a farm collective. As well as saving money, there is evidence that growing your own food improves your mental and physical health.’

The need for a food system redesign

Whilst adopting a plant-based diet is crucial, Taherzadeh argues that the major problems we see in our food system (overconsumption, food waste, biodiversity loss and malnutrition) are symptoms of our endless pursuit of economic growth. In a new perspective article in Nature Sustainability, over 30 authors (including Taherzadeh) offer a blueprint for an alternative food system. This system is designed not by the logic of growth, but by principles of sufficiency, regeneration, distribution and care.

Text: Lisanne Bos

This website uses cookies.  More information.