Cooking up calories

Cooking these days is the basis for everything from contrived television competition to celebrity status yet there is still room for the rather unusual, if staid, aim of cooking being a way to prepare food for you and your family. It is no accident or whim that we cook our food, as cooking significantly changes our food, often for the better, but sometimes not depending on the food and depending on the way you cook it. In a new study for instance it has been shown that cooking liberates a lot more calories from fat.

In evolutionary terms being able to get extra energy from what food we had by cooking it allowed some of the leaps forward that we have made as a species. It has been well established that cooking protein and carbohydrate liberates extra calories from these foods. There is little research though that shows what effect cooking has on calories (or kilojoules) contained in fat.

In this study four groups of mice were fed four separate diets over the course of 20 weeks. The diets were all based on peanuts and the four groups were; raw and whole, raw and blended, roasted and whole, and roasted and blended. By keeping track of each mouse’s weight, food intake, and exercise the researchers found that the mice derived more energy (calories/kilojoules) when the peanuts were cooked. The mice actually ate more of the raw peanuts although they gained about the same amount of weight as those eating cooked peanuts indicating that the cooking liberated more kilojoules from the lesser amount of food. Analysis of the mice’s foeces also showed that the fat had been digested more when the peanuts were cooked.

The researchers discovered that when cooked the peanut cell walls change in such a way that more fat can pass out of the cells. Peanuts are about 50 per cent fat but most of this is inaccessible when you eat them raw. Cooking also reduces the numbers of proteins called oleosins in the peanut cell walls and these oleosins function to hinder digestion.

In the end it means cooking releases more energy from fat from your peanuts, so provided you eat the same amount of nuts, it is another reason to go raw when possible.