Simply explained a calorie is the energy we get from food and too much of this energy could mean we become overweight. This basic principle was discovered way back in the 1800s when an American chemist, Wilbur Atwater, devised the system on which calorific values are still based today.
In order to establish how much energy was produced by certain foods, Wilbur burned food and then measured how much energy was produced. He then measured the amount of energy in the body used up by calculating the amount of energy in undigested food in water products.
In doing all of this Atwater concluded that every gram of carbohydrate produced four calories, every gram of fat produced nine and every gram of protein produced four calories.
These very figures have been used ever since as the formula for calculating calorie content of food.
Though nutritionists have always known these values are approximate, recently experts have suggested that the calorie content of items could be as far as 25 per cent out due to the texture of the food, its fibre content and how it is cooked.
Experts have said that even the simple act of chewing food uses up energy and the higher the amount of protein and fibre in our food, the harder our bodies must work in able to process it.
Nutritionist Dr Geoffrey Livesey says: “People need to be given the right information to make the right choices, following the latest scientific understanding, because if you are not following the science, you’re following something else.”
However, head of nutrition at the Medical Research Council, Dr Susan Jebb has said that though it is correct that some calories will be more filling than others, in the grand scheme of things these are very small differences and what is really important is eating healthily. “What’s important is to eat fewer calories so that the body is in negative energy balance. How you calculate it doesn’t.