Why am i craving sugar
Brain and sugar 03
A crucial point about all this is that time is a vital factor here: If you eat beans that are digested slowly your blood glucose levels will only raise slowly. This gives your feedback mechanism time to work without overshooting the target and without the big oscillation in glucose levels that follow fast and big raises in glucose levels. When you eat refined food that are flooding your system with glucose your natural regulation will not react fast enough. In the first phase you glucose levels will get too high. This will trigger a slow but big insulin response that will overshoot its target and leave you with less glucose in circulation than you actually need. Just like Henry Rollins overdid his LSD you end up with too much insulin circulating. This will over time act to remove so much glucose from blood that you don’t have enough for normal function. Which leaves your feeling in need of rest and food.
There is a basic tension between this and your learning / reinforcement mechanisms: The most basic mechanism for learning is simple association by either proximity or by similarity. The reinforcement system uses proximity and will associate any progress or success with a tiny squirt of dopamine and a pleasant feeling of potential or promise. This system relies on guessing that your action is the cause of the progress and blindly labeling your action as leading to the progress.
If you stick to basic automatic learning, the initial rush of energy that you get from rapid rising blood glucose will influence your behavior because it is close in time to the behavior that causes it. The following “crash” where you feel depleted will influence your learning and your behavior less, because it is a bit further apart
If you have enough energy to establish and maintain a bridge between your long term experiences and your food habits, this is something that you can avoid. If you have enough self control to shape your habits into something that avoids the peaks and drops in glucose availability you need never be a victim of this kind of dysregulation. The problem is that if you have a stressful life, if you need your resources to deal with ongoing crisis, it will then be quite hard to add a habit changing task on top of all else that is demanding of your attention. You then have to deal with whatever life situation that you are in, without the benefit of a stable supply of energy for physical work and for controlled behavior.
Action that leads to good results will then be tinged with a feeling of promise and an enhanced willingness to invest more energy.
The wonderful thing about this kind of learning is that it works totally on automatic. You don’t have to do a thing. But this is not all good: The problem with it is that it only works effectively with pairs of action and results that are close in time. This is a structural limitation that is “built-in” and comes with the fundamental idea of the system: It only works with action-result pairs that are nicely sitting next to each other within a fairly narrow time frame. And if you start to allow distant pairs to be associated, you need a careful selection of pair-items or to accept that most of your pairings will be between actions and results that are really not related as cause and effect. Like when people learn that wearing two different colored socks will lead to a better blind choice of subject at your exams.
In other words: The most basic system of learning is only effective towards learning short term strategies. To learn the use of long term strategies you need to rely on less basic and less automatic systems. This will be extremely important in later discussions. But you can already see that there is a basic tension between the time frame of the slow insulin regulation system and the narrow automatic learning by association system. This will be important later.
The desire for some researchers (Davis et al., 2011) seems to be to make food addiction an instance of a general class of addictions, so that food addiction shares chemical mechanisms with ´conventional addictive drugs´. In this view the task is to uncover the causal path from overeating to changes in brain chemistry or brain physiology that will support an ongoing addiction.
The problem with this strategy is that it presupposes:
a) That conventional drug addiction is in fact supported by changes to the brain that are caused by the addictive drugs themselves.
That this is not the case needs to be argued separately.
b) That we for food addiction can map out a similar causal path
c) That there are no other valid explanations for food addiction
The alternative strategy that we are going to explore is based on the view that food addiction is not primarily supported by changes that are specific to the intake of food – ei. not the effect of changes that can be traced to chemical or physiological effects of the food items ingested.
Instead of assuming that, we are going to have a look at the energy circuits (mainly glucose metabolism) that eating feeds (in the most literal sense) and the consequences that different states of energy supply or depletion has on brain function in general and on self control in particular.
In simple terms the strategy is to explore food addiction for a general mechanism that can be applied in explaining the wider scope of addictions, including those that are now seen as caused by effects of the addictive substance. Instead of treating food addiction as a subspecies of drug addiction we are going to treat drug addiction as a subspecies of resource addiction, or more loosely a kind of food addiction.
Davis, C.ab , Curtis, C.a, Levitan, R.D.b, Carter, J.C.c, Kaplan, A.S.b, Kennedy, J.L (2011) Evidence that ‘food addiction’ is a valid phenotype of obesity, http://www.ncbi.nlm.nih.gov/pubmed/21907742