A clutch of companies from the eating and drinking out market have begun trials disclosing the number of calories contained in menu items.

The initiative, co-ordinated by the Food Standards Agency (FSA), will see a range of companies include Mitchells & Butlers (M&B), Marks & Spencer, Pret A Manger and Subway disclose calorie counts across a number of outlets.

In the case of pub and restaurant operator M&B, it is carrying out trials at 14 Harvester outlets and 12 Scream bars, meaning it will be able to track behaviour at both a food-led format and a wet-led format.

The tests, which involve a total of 18 companies in the foodservice space and will run across 450 outlets, will last for about four months.

Each company has agreed to display calorie information for food items, print calorie information on menu boards, paper menus or on the edge of shelves and ensure the information is clear and easily visible at the point where people order their food.

Tim Smith, chief executive of the FSA, added: “We are pleased that such a diverse range of companies has agreed to work with us by introducing calorie labelling at the crucial point where their customers make a decision about what to eat.

”Our aim is to ensure that consumers have better information so they can make informed choices to improve their diet when eating out, whether that is a snack on the go, a meal in a staff restaurant or at a table being served by a waiter.”

Independent research will assess how easily customers understand and use the system and gather feedback from the restaurants themselves to look at practical issues and the costs involved in providing the information.

It is thought that the data gathered will inform the next steps for a wider roll-out of calorie labelling on menus.

Alastair Scott, public affairs director at M&B, said: “We would expect it to impact the behaviour of some of our customers in and are sure there will be much to learn from this experience.

“Learnings from off-trade labelling suggests that calories on packs tends to influence the behaviour of the health conscious only. It remains to be seen whether this trend is repeated in the pub, where for many the occasion is a treat not an everyday event.

“We are using enough sites to ensure we come to the end with something that is statistically meaningful.”

The new trial menus at M&B’s Harvester and Scream formats reveal a spread of dishes across the calorific spectrum - from a tuna and rice dish at 500 calories up to a BBQ Stack Burger at 1550 calories at Harvester and from a chicken salad at 260 calories to an Ultimate Cheese Burger weighing in at 1610 calories at Scream.

Other companies included in the scheme are Compass, KFC, Merlin Entertainments, Waitrose and Wimpy.