Unhealthy diets are bad for the environment, study finds

Unhealthy food and drink such as cake, sweets and alcohol account for nearly a quarter of diet-related greenhouse gas emissions, according to a new study.

The research, which analysed at more than 40,000 branded items and 3,000 generic foodstuffs, suggests that changing our eating habits could help fight the climate crisis as well as improve our personal health.

By providing a far more detailed picture on the impact of a person’s diet than previous studies, the study suggests ways that people can take individual action to limit their impact on the environment, according to the team at the University of Leeds.

That could include something as simple as cutting out the daily morning coffee, said lead author Dr Holly Rippin, a post-doctoral researcher based at the university’s School of Medicine.

“We all want to do our bit to help save the planet and the decisions we make can contribute to that cause,” she said.

“It’s true that we do need big cultural changes – such as significantly reducing our consumption of meat and dairy products which together contribute around 46 per cent of our diet-related emissions.

“However, our work shows that small changes can also produce big gains. You can live a more environmentally sustainable life by just cutting out sweets and drinking less coffee."

The researchers studied the greenhouse gas emissions linked to production and transport of individual foods and brands and used the World Health Organisation Recommended Nutrient Intake guidelines to measure the nutrients of those foods.

They then analysed the food and drink consumption of 212 adults recorded online over three 24-hour periods.

The study found that sweets, cakes and biscuits account for 8.5 per cent of food-related greenhouse gases, while drinks such as tea, coffee and alcohol contribute a further 15.1 per cent.

Non-vegetarian diets produced 59 per cent more greenhouse gas emissions than vegetarian diets.

Men’s diets contributed 41 per cent more greenhouse gases than women, mostly because of their greater intake of meat.

“Other studies have suggested that men’s higher diet-related emissions reflected their need for more energy,” said Darren Greenwood, a senior lecturer in biostatistics at the university. “Unfortunately, it appears that they look to get those calories from meat rather than lower impact foods.”

The team highlighted the 2019 IPCC Climate Change report that suggested switching to a healthy diet based on unprocessed, plant-based foods could prevent one-fifth of premature adult deaths while reducing diet-related greenhouse gas emissions by 80 per cent.

Professor Janet Cade from the University’s School of Food Science and Nutrition, said: “This detailed study confirms that diets that are better for the planet’s health are better for our own personal health too.

“It also raises more issues around the labelling of food as different brands of the same product vary in their environmental impact.”

The study, published in scientific journal PLOS One, was funded by a University of Leeds award as part of a programme to encourage interdisciplinary research addressing the United Nations’ sustainable development goals.