Thursday 6 January 2011


The book I am currently reading is Robert Atkins' "New Diet Revolution". It is not that I am trying to lose weight but I just wondered what is behind it. And I think he has a lot of good points that standard nutritional theory has not fully appreciated yet.

The main claim of Atkins is that sugar and refined carbohydrates are more problematic than fat. This goes for both health and weight issues. I did not realize this initially but it makes sense. To make an analogy: flooding the organism with sugar is like pouring oil into a fire - you are adding highly reactive fuel. In more chemical terms: glucose being an aldehyde is a reactive molecule. And if too much is present it will cause problems, for example react with the amino groups of proteins - the Maillard reaction. What does the body do against it? Produce insulin to make sure all the energy is stored in a safe place - as glycogen or fat. And if everything is stored, there is probably enough excess insulin to lower our blood sugar level enough for the next hunger attack and cravings of carbohydrates. Aside from increasing fat tissue, too much insulin production may eventually also overstrain the pancreas and cause diabetes.

Another interesting point is that food energy, i.e. "Calories", is not everything. The idea is that the standard oxidation energy determined in a bomb calorimeter cannot necessarily be transferred 1:1 to energy available for the body. Atkins states that he has examples where a person would gain weight when consuming a specified amount of calories in carbohydrates and lose weight when they would consume the same amount of calories in fat. The energy conservation law also holds in biology of course, so where does the energy go? Probably into body heat. This leads to what another interesting nutritionist, Udo Pollmer, says: That people on a diet (which is probably low fat) feel cold quicker. [1]

As I just discussed, calorie counting (which seems a natural application of the energy conservation law) may not even make sense from a purely biochemical point of view. A point which is probably more important, that both Atkins and Pollmer mention, is psychology. Basing a diet on severely restricting yourself on such an abstract thing as the number of calories does not work for most people. The body has a built in mechanism to control food balance and it seems difficult to fight that with willpower. Eventually one would just stop the diet and "binge eat". Or maybe your body will get the calories it wants in a more subtle way, for example through high calory drinks (cola, fruit juices, alcoholic beverages, milk, ...). So what restricting calories does, is probably just telling your body that food is scarce and it should try to get as much as possible from wherever it can.

[1] edit: actually another reason is that in ketosis energy is lost in chemical form, i.e. high energy molecules like ketone bodies are excreted.

1 comment:

RARORAC said...

Another problem with calorie counting is the dependence of calorie intake on metabolism. That's why it is often suggested to eat a greater number of small meals to keep metabolism running rather then to fall into famine mode which can also lead to the burning of lean muscle instead of fat.