Unhealthy diets also tend to be bad for the planet according to researchers at the University of Leeds.
The researchers studied the greenhouse gas emissions linked to the production and transport of individual foods and brands and used the World Health Organization Recommended Nutrient Intake guidelines to measure the nutrients of those foods.
They found that sweets, cakes and biscuits account for 8.5% of food-related greenhouse gas emissions and drinks such as tea, coffee and alcohol contribute to 15.1%.
They also found that non-vegetarian diets produce 59% more greenhouse gas emissions than vegetarian diets.
The team concluded that a healthy diet based on unprocessed, largely plant-based foods is also a sustainable one.
They point to the 2019 IPCC Climate Change report that suggests a switch to this type of diet could prevent one-fifth of premature adult deaths while reducing diet-related greenhouse gas emissions by 80%.
Lead author Dr Holly Rippin said: ‘We all want to do our bit to help save the planet and the decisions we make can contribute to that cause. 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% 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 also found that men’s eating and drinking habits also play a major role, contributing 41% more greenhouse gasses than the food and drink intake of women – largely due to their liking for meat and, to a lesser extent, drinks.
Darren Greenwood of the University’s School of Medicine added: ‘Other studies have suggested that men’s higher diet-related emissions reflected their need for more energy. Unfortunately, it appears that they look to get those calories from meat rather than lower-impact foods.’