US fastfood chain Wendy's has begun a trial menu offering of meals for customers who are following reduced-carbohydrate diets.

Customers had previously been able to ask for a cheeseburger or a grilled chicken sandwich without the bread bun, but now the company has decided to actively promote bunless sandwiches for the first time.

As part of the test beginning this week, customers at 248 Wendy's restaurants in six US markets will be able to order new "Meals for Carb Counters".

These meals feature either a cheeseburger or grilled chicken breast on Romaine lettuce, topped with slices of tomato and red onion, with a Caesar side salad and a medium Diet Coke. The entire cheeseburger meal has six grams of carbs, while the grilled chicken meal has eight, Wendy's said.