Lunch makes a big difference to your day. The World Health Organisation says that the right diet can raise productivity by 20%. Get it wrong and you’ll have a difficult afternoon, feeling distracted or drowsy. Get it right and you’ll be well-fuelled, well balanced and ready to take on anything (until dinnertime). What’s the secret? And might some countries pick up a competitive edge from their midday dining habits?

We decided to find out.

A heavy lunch that leans on stodgy carbs, like bread, is usually followed by a slump in productivity as blood rushes to the stomach. But skip the meal and your blood sugar levels are likely to hit the floor, together with your attention. And if you fill the gaps with sugary treats and cups of coffee your mood with go up and down like a yo-yo.

• A quick straw poll among our worldwide network of Regus staff revealed the following typical lunch choices:

• Mexico: tortillas and tacos, filled with beans and vegetables.

• UK, US and the Netherlands: chicken is the most popular filling in UK sandwiches, ham in the US and cheese in Holland.

• Brazil: rice and beans with chicken or beef.

• Australia: chicken parmigiana – chicken topped with ham, cheese and sauce.

• France: baguettes or salads. The jambon-buerre, a baguette with ham and butter, is the classic quick lunch there.

• China: dim sum, rice or noodle dishes.

• Japan: bento boxes with sushi, rice, chicken and pickled vegetables.

• Sweden: cod roe sandwiches.

With this in mind, it makes good business sense to see if there’s such a thing as the perfect working lunch from the perspective of keeping productivity levels high.

Perhaps unsurprisingly no one nation ticks all boxes, but based on the nutritional content of the lunches from the various we looked at the Japanese bento box scores highly. Offering a little bit of everything – rice or noodles, protein in the form of beef, fish or chicken, and some pickled vegetables – it’s a balanced meal that ensures a steady release of energy throughout the day.

Really, though, you can find inspiration in the food of all these countries. And if you use those ideas to put together a well-balanced dish that will keep you on an even keel over the course of the afternoon, then your productivity will increase – the perfect working lunch.

What do you do to keep energised in the workplace? We’d love to hear it.