BBC reveals some popular fast-food chains have been inaccurately reporting calories

Fast-food chains may have been inaccurately reporting the calorie content of some of the items on their menu, a recent investigation has suggested.

It is estimated that almost two thirds of adults in England are overweight or dealing with obesity, but as part the government's strategy to tackle the issue restaurants, cafes and takeaways in England must now state calorie information on their menus.

But an investigation by BBC Morning Live’s Briony May Williams, aired this morning, has revealed that some fast-food chains have been inaccurately reporting the calorie content of some items on their menus, with three fast-food chains found to have underreported by as much as 30%.

The test, conducted by Dr Nazanin Zand, Professor in Food Science and Nutrition at the University of Greenwich, showed that some popular fast food chains have some incorrect calorie labelling on their menus.

Dr Zand explains that the calories found on menus are found using nutritional software to enter the recipe and use nutritional databases for the calorie count.

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But, when asked how accurate this method is, Dr Zand says the software has some "inherent limitations".

"In practice the chefs are more relaxed in terms of measurements and also the software itself sometimes doesn't take into account the cooking methods," she explains.

For their own investigation Dr Zand's colleague Dr Elena Lopez used a specialist kit to analyse the calories in meals from the UK's most popular fast food chains McDonalds' bacon double cheeseburger at 495 calories, Greggs' sausage, bean and cheese melt at 454 calories and KFC's Zinger supercharger tower burger for 650 calories.

The investigation found that nearly all of the food they tested was higher, and in some cases were above the 20% legal threshold.

Menu items tested revealed the cheeseburger had a calorie count 31% higher than advertised, the chicken burger was 28% higher and the sausage bean and cheese melt was 24% higher than it should be.

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The investigation also tested the same foods from three different branches and found there was a difference in calories across the branches.

"In the case of the double cheeseburger in one particular branch the calorie content was about 30% higher than what was declared on the menu, but the other two branches were much closer to that value," Dr Zand explains.

"With the melts' one was about 24% above what was declared, the other two were closer. And in the case of the tower burgers two of the branches were showing about 30% higher than what was declared on the. menu and one was showing 9% lower.

Registered dietician, Claire Thornton Wood, told BBC Live that she isn't surprised by the results because they are natural food stuffs.

"A burger will be the same wage as the next burger, but it might have come from a slightly different part of the animal, which is slightly more fatty," she explains.

"The other thing is human error. They might do 20 fries or they might do 25 they're not counting them so there will always be a little bit of variation and the same thing goes for sauce and source is quite high in fat," she adds.

When asked if companies need to make more of an effort to get that meal closer to those calories Thornton Wood responds: "Ideally it would be good and it shouldn't be that difficult, but there always will be some natural variation," she says.

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Williams concluded that for the calorie labelling system to work as its intended, it's important that we can trust what's printed.

"But the morning live investigation has shown that as things stand, the labels don't always reflect what's on the plate. accurate or not," she adds. "Calorie should only ever be a part of the picture when it comes to making healthy and enjoyable food choices."

BBC Live contacted the fast-food chains tested for their response.

"KFC told us its menu items are all nutritionally analysed in an accredited lab, but that with natural ingredients like chicken there will always be some variation in calories," presenter Rav Singh reads. "It said following our results it thinks some of the variables informing the calorie content are outside of its tolerances, and that it is investigating."

"McDonalds told us it thinks our order was prepared incorrectly in the burger, which was over 30% higher in calories," Gabby Roslin reads. "It said it is disappointed that on this occasion it appears to have fallen short of its high standards. And the restaurant has been reminded of the correct procedures."

Singh also read out the response from Greggs, which said: "there can be variances due to the nature of its products and ingredients used". It added that it would "continue to work with colleagues and suppliers to improve its processes."

Watch Morning Live every weekday on BBC One from 9.15am or catch up on iPlayer.