Diners are more likely to shun meat and choose environmentally-friendly, vegetarian options if the menu tells them the carbon footprint of their meal, a study has found.

       The UK Government has recently forced restaurants to reveal how many calories are in their meals.

       German researchers looked at the impact of adding eco labels in a similar way, with more than 250 study participants shown either menus with an environmentally-friendly default option, or dishes with colour-coded labels to reveal their environmental impact.

       For example, in the first menu a pitta bread with falafel was presented as the most prominent dish, while a version with chicken instead of falafel and a beef option were listed in smaller print underneath. In the second menu, falafel was given a green-coloured label, while chicken and beef were given amber and red, respectively.

       Restaurants urged to have 'climate-friendly' menus

       Study participants were asked what they would order off these fictional menus. When climate-friendly tags were present and the default option was a green-rated dish, the customer was more inclined to eat sustainably.

       When the low emissions choice was the default, there was an average reduction in emissions of around a third, data show.

       Even when green, amber and red labels were used instead of menus with a green-rated default option, greenhouse gas emissions dropped by 13.5 per cent.

       The researchers of the study, published in the journal PLOS Climate, said: “If we want more climate-friendly restaurant visits, highlighting dish components on a menu can really be an important parameter because it communicates what is normal and recommended. It may also be one of the easiest things restaurant owners can do.”