The chicken mayo on granary looks great and is surely far better than burger and fries, but is there much difference or are we being fooled into thinking some lunchtime choices are healthier than others? A recent investigation by the Good Housekeeping Institute found that a Pret A Manger mozzarella sandwich had more fat and calories than a Big Mac – food for thought. Take our quiz to find out just how healthy your diet really is.

While we shouldn't judge our lunch choices on calorie and fat value alone, it's important that we look at the whole package, checking salt, sugars and artificial additives, and remembering that we need to be concerned with good and bad fat, not necessarily high fat.

Making the white choice
The ubiquitous sandwich – how would a day at the office get by without it? But nutritional therapist Jane Frank thinks we scoff more bread than is healthy for us in terms of our gluten intake (www.franknutri.co.uk) and that modern manufactured bread isn't worth eating.

'Someone may think they are buying a healthy lunch when they choose a sandwich made with brown bread,' says Jane. 'This could just be white bread with added colouring. Granary bread is just that, with crunchy bits added in as well.'

Sweet like chocolate
You're smugly eating a fruit bio yogurt for your dessert while your colleague is tucking into a bar of chocolate? Yes, it's her teeth that are going to drop out, not yours... but have you checked the sugar content on the packaging? You might be surprised to find there's not much difference, and even low-fat versions can be high in sugars.

'Because protein and fat are usually found together in nature if you lower the fat you invariably increase the carbohydrate content, which usually means sugar in one of its many guises. If it ends in '-ose', it's sugar,' says Jane.

Love the label
Don't be fooled into thinking that something is healthy when it isn't. Checking the label reveals a lot and highly-processed diet versions tend to make up for lost flavour through additives and salt. For example, per 100g, Go Ahead! Cranberry cookies have 0.5g salt, compared to McVitie's Jaffa Cakes, which have 0.1g.

'We shouldn't eat more than 5g of salt per day and should avoid foods containing more than 5g per 100g,' says Jane.

Eat right
Make sure your desk is stashed full of healthy basics like oatcakes, nut butter, seeds, nuts, and dried fruits, then plan ahead and bring in fresh food to make your lunch. Why not give yourself a diet makeover?

For sandwiches, Jane suggests using sourdough or rye breads where possible. Have one slice and top with a protein food such as chicken, hummus, tuna, sardines, or cottage cheese, and then add high-fibre nutrient foods like raw vegetables, beansprouts, watercress, tomatoes, and grated carrot.

Jacket potatoes are also good options, use olive oil to drizzle and then toppings like cottage cheese or prawns and lots of salad vegetables. They can be bought everywhere, as well!

Instead of picking diet or fruit yogurts, Jane says, 'I encourage people to buy plain bio-live full-fat yoghurt and chop up some fresh fruit in it.'