Fast food products are not consistent with the human appetite regulating system, a new study has found. Researchers from the international nutrition group compared the number of calories found in fast food meals with those in traditional dishes from Britain and Africa to assess the role of energy density in regulating food intake. They found that food with high energy density caused volunteers to eat more calories than they actually needed. A typical fast food meal contains high energy density - one and a half times more than a traditional British meal and two and a half times higher than the average African meal - so only a small amount is needed to increase calorie intake. The researchers concluded that a diet high in fast foods will increase a person's risk of weight gain or obesity, even though they may feel that the portions are no different to a to a traditional meal, and that they are not particularly full. 'We all possess a weak innate ability to recognise foods with a high energy density. We tend to assess food intake by the size of the portion, yet a fast food meal contains many more calories than a similar-sized portion of a healthy meal,' said Professor Andrew Prentice, head of the international nutrition group. 'Since the dawn of agriculture, the systems regulating human appetite have evolved for the low energy diet still being consumed in rural areas of the developing world, where obesity is almost non-existent. Our bodies were never designed to cope with the very energy dense foods consumed in the West and this is contributing to a major rise in obesity,' he added. In light of their findings, the research team claims that further analysis on fast food eating habits is needed to help provide better dietary advice.