Lunchbox: Kylie O'Donnell, 25, securities officer A deli sandwich - red pepper bread with Emmental cheese, honey mustard and salad, accompanied by Diet Lilt

According to Juliette Kellow, state registered dietician and associate editor of Slimming Magazine, such a meal would give Kylie 585 calories of which 44 per cent come from carbohydrate, 18 per cent from protein and 37 per cent from fat of which 17 per cent are saturates.

"Buying lunch from a shop which makes sandwiches while you wait gives you the opportunity to make healthier lunchtime choices," Kellow says. "If you're trying to keep fat intakes down, watch out for speciality breads which contain oil, such as ciabatta and focaccia.

"The fat and saturates content of this meal are a little high, with most being provided by the bread - which contains oil - and cheese. Most people should have less than one third of their calories from fat and one 10th from saturates. However, avoiding butter on the sandwich and having honey mustard instead of mayonnaise helped to prevent fat intakes from being higher.

"Most people should have five servings of fruit or vegetables a day. Although there was red pepper in the bread and some salad in the sandwich this isn't enough to count as one serving. Asking for extra salad to be served would be a good idea and would increase fibre intakes.

"On the good side, this meal is packed with calcium - a mineral needed for strong, healthy bones. The Emmental cheese provided most of this nutrient, and contributed to good amounts of vitamin A".