Some high-fibre foods, which are sold as low in calories, may actually contain, in the extreme, up to 25 per cent more calories than the label suggests, nutritional experts have said.

It means that some high-fibre foods targeted at people on a diet are actually more fattening than people are led to believe, said Geoffrey Livesey, an independent nutritionist based in Britain who has advised the UN`s Food and Agriculture Organisation.

Dr Livesey told the American Association for the Advancement of Science meeting in Boston that consumers have been unknowingly consuming extra calorie in high-fibre food for decades because the system for assessing calories goes back to the 1970s and even earlier, according to the Independent.

It means that if people follow the daily recommended intake of 18 grams of fibre, they could be consuming more than 250 extra calories each week without realising it, he said.

Food manufacturers and government agencies have consistently misled consumers over many years about the number of calories contained in food, said experts.

Government assessments about the amount of energy in food assume that the caloric value is the same whether the food it cooked or raw, but scientists know that raw food provides fewer calories because the body expends energy breaking it down, said Richard Wrangham of Harvard University.
"There is a lot of misinformation around calories, and it is crucial for the consumer, whether they are on a diet or not, to have the correct information about what they eat," he told the meeting.