The cover article on the July 2009 issue of New Scientist looks at how calorie counts on nutrition labels can be off by as much as 25% depending on, among other things, how the food is cooked or the texture of the food and even the crunchiness of the food. What apparently has been overlooked is how much energy is required to breakdown and digest our food.

For example, scientists in Japan fed one group of rats hard food pellets and another group the same pellets only softened – both groups had the same calorie content and flavor. After 22 weeks, the group receiving the softer pellets were obese and had more abdominal fat. Turns out that the rats who ate the hard pellets had to work metabolically harder to digest the food. Does this concept apply to humans?

Well a similar study was done at the University of Tokyo in Japan with similar results. A survey of 450 women found that those who ate softer food had larger waist lines. This really shouldn’t be too surprising a result. Most of our foods today are highly processed with sugar and refined flour – in other words, with most of the dietary fiber stripped out.

The take-home message is that our bodies have to work harder to digest food depending on the texture/hardness and the fiber content. Highly refined foods make it too easy for our bodies to digest food and our nutritional labels do not reflect this. Gives us yet more reasons to eat more foods high in fiber, complex carbohydrates and protein.

For a snack-calorie chart, check out this list published by the National Institutes of Health.