A “one-size-fits-all” solution to addressing the climate crisis through our diets could be unhelpful, as how we eat affects the environment in different ways depending on where we live and how our food is sourced, according to a new report.

Although reducing the consumption of meat and animal-based products globally could lower greenhouse gas emissions, it could also have adverse impacts on people’s health and nutrition in some countries, according to a report published online in the Global Environmental Change journal on Monday.

The report, which assessed dietary patterns across 140 countries, paints a complex picture of the country-specific implications of dietary changes on both people and the environment.

“We need to be careful about oversimplifying things or prescribing a ‘one-size-fits-all’, western-centric solution to the challenges of diet and climate,” said Martin Bloem, a director at Johns Hopkins Center for a Livable Future and one of the co-authors of the study.

The report notes that many Britons are choosing vegetarian diets to reduce the environmental damage caused by their lifestyles, but suggests that they may better off going “two-thirds vegan” – eliminating animal products including meat and dairy from two in three meals.

For a British person, going vegetarian would reduce the climate impact attributable to their diet by 36%, while cutting meat and dairy out of two-thirds of their meals would reduce it by 61%. That’s because dairy has a relatively high carbon footprint.

In other countries, the impact of meat-based diets could be hugely different – for example, a pound of beef produced in Paraguay contributes nearly 17 times more greenhouse gases than a pound of beef produced in Denmark, partly to do with the deforestation involved in beef production in Paraguay.

According to the study’s authors, diet-related solutions to the climate crisis ought to be sustainable and address the problems of undernutrition, obesity, poverty and economic development.

Achieving healthy diet in most low- and middle-income countries could require an increase in greenhouse gas emissions and water use due to food production.

Babies in Nepal get quarter of calories from junk food, study finds Read more

“It is critical to recognise that different countries have different priorities and are at different stages of development – meaning there are different imperatives for these countries and their populations,” Bloem said.

“A top-down diktat that recommends a plant-based diet without taking into account the nutritional needs of vulnerable populations or the availability of certain foodstuffs is neither helpful nor appropriate,” he added.

“The fact is that in low-income countries, some people, especially young children, will need to eat more animal products, particularly dairy and eggs, to get adequate protein, vitamins, and minerals. Consequently the diet-related emissions and use of freshwater in these places will have to rise. This means that in high-income countries, where people generally have enough to eat – although [they] are not necessarily healthy – the shift towards more plant-forward diets and away from carbon- and water-intensive consumption patterns has to happen faster.”

The report suggests that in the UK, while animal foods can be an important source of nutrients for young children, meat and dairy are overwhelmingly responsible for the greenhouse gas footprint of British diets. Plant foods account for 69% of the calories consumed in the UK but only 12% of greenhouse gases and 40% of the water footprint.

“The solutions are not uniform and will inevitably involve trade-offs,” said Bloem.