The current method of measuring the calorie content of foods could be flawed, says Professor Martin Wickham of Leatherhead Food Research.
Energy value of foods is most often allocated by using the Atwater general factor system, in which the main food components – protein, fat, and carbohydrate – have a single energy factor, regardless of the food in which they are found or how they are processed. Carbohydrates and proteins are considered to contain four calories per gram, fat nine calories per gram, and the system also includes a value of seven calories per gram of alcohol.
But momentum has been building to overhaul the way that calories are calculated, as evidence increasingly points to energy being locked up in the structure of some foods, meaning that it is not used by the body.
Professor Wickham explains why it may be necessary to revise how we calculate calorie content.