The brain of a conditioned hypereater
On Monday I touched upon how the change in the composition of food over the past 2-3 decades has contributed to a considerable increase in North American food consumption. Today, I want to discuss the difference between the brain of a conditioned hypereater to the brain of a non-hypereater.
Kessler, along with a colleague, Dana Small, developed a questionnaire to help differentiate between conditioned hypereaters and non-hypereaters. The scale they developed had 11 statements that allowed them to distinguish between “high” and “low” degrees of conditioned hypereating. Such statements included, “When it comes to foods I love, I have no willpower,” and “I have days when I can’t seem to think about anything else but food”.
When we have an urge to eat something, there is a release of dopamine in the reward centre of our brain, specifically the nucleus accumbens and the amygdala. This is referred to as the anticipation phase. This surge in dopamine increases our motivation to seek out the food that we initially desired. This feedback loop continues until we accomplish the task of locating and ingesting the food. Once ingested, the release of dopamine decreases, however, the ingestion of the food causes a release of endorphins – our natural opioids. This is referred to as the reward response. This is the response of a non-conditioned hypereater.
Small and Kessler wanted to examine the response in conditioned hypereaters using functional magnetic resonance imaging (fMRI) and self-report methods. Participants were first asked to smell a chocolate milkshake with the aim of eliciting the anticipation phase (i.e. secretion of dopamine) and then to taste the milkshake to elicit the reward response (i.e. secretion of endorphins).
In non-conditioned hypereaters, the continuous smell of the milkshake eventually becomes less pleasant overtime due to habituation due to a decrease in the secretion of dopamine. But the response in the conditioned hypereater was significantly different.
The smell of the milkshake did not become less pleasant overtime. In fact, the conditioned hypereaters self-reported that the smell became more pleasant overtime. Additionally, Kessler and Small noted a significant difference in the amygdala of hypereaters; the amygdala continued to remain activated during the ingestion phase. To remind you, the amygdala is associated with the anticipation of reward, not the reward itself. Therefore, the activation of this area of the brain should become lessened during the ingestion/consumption phase.
Thus, “eating rewarding food can enhance the drive for more rewarding food”. It would appear that the motivation to continue eating becomes heightened by the process of eating in conditioned hypereaters. In non-conditioned hypereaters the process of eating lessens the drive to eat more, which in turn, allows the individual to stop eating once sated.
As Small states, “The heightened amygdala response drives the whole circuit out of whack”.
Fortunately, our brains are fairly malleable and Kessler does touch upon various ways to combat conditioned hypereating. I will be talking about such strategies in future posts. Stay tuned.