Why do people overeat? Understanding the causes may help to stop overeating – so here are some aspects of this behaviour explained – why do people overeat?
The behavioural chain that constitutes overeating is a perplexing one indeed: why do people overeat and what specifically elicits overeating? The taste of food? The sight? What? In essence, what makes some people more inclined to actually eat food when it is available, in contrast with others who are able to neglect it, or simply just not notice it is there?
I’ll digress for a brief moment. Culturally, there are few differences as stark between America and Europe as those that can be found in the airport. Give me a three day snow storm in the Shangri La that is St. Louis over a three hour delay in CDG, as long as internet connections are included in the deal, of course.
American airports are veritable palaces of eatertainment pleasure: go to the domestic departures area of any major American city, and you are met with 17 different variations of Vietnamese-fusion restaurants. Where as the International Departures of Charles De Gaulle? You’ll find a coin-operated coffee machine. Maybe, just maybe, you’ll strike gold with the Latvia coffee shop that is open for three and a half hours on a Tuesday. Just not this Tuesday. Some of them.
Part of my love for American airports is the variety and access to many kinds of food. Since I don’t live here permanently, this is a wonderful novelty. However, this plethora of goodies is bad news for the See Food, Eat It types (of which I’ll happily include myself). Recent data has shown a clear biological relationship between sensitivity to food cues, and an increased risk for obesity.
The latter point is not exactly new news. For a long time, Sensitivity to food cues has been implicated as a risk factor for the development of obesity. What appears to be most exciting, however, is that this self reported trait does indeed have biological, neuronal correlates. In other words, people who report a tendency to See Food Eat It, really and truly are more likely to See Food and Eat It. Maybe lots of it, and here is why:
For those individuals who report having External Food Sensitivity (EFS), appetizing food elicits a strong chain of reactions in the brain that speak to the core of motivated behaviour.
1. Specific connections in the human brain are differentially affected by EFS: while subjects viewed appetizing compared with bland foods, High EFS scorers were associated with reduced differential connectivity in a network in the brain that is specifically related to Eating behaviour (including the ventral striatum, amygdala, medial prefrontal, and premotor cortices) (Kelley et al., 2005).
2. Increased EFS is associated with increased preference for the sort of high calorie, sweet foods such as Pictures of chocolate cake or ice cream. Here, it was suggested that this might operate by affecting connections between components of the ‘feeding network.’ (including the ventral striatum, amygdala, medial prefrontal, and premotor cortices) (Kelley et al., 2005).
3. Individual differences in EFS constitute the behavioral expression of variation in network coupling among neural structures implicated in feeding.
4. Finally, high EFS individuals displayed a reduction in the change of connectivity between specific brain regions of the feeding network. Together, these findings provide evidence that less efficient connectivity among relevant brain regions might represent a ‘neuronal marker’ for increased vulnerability to develop abnormal behaviors, including food craving and overeating.
So, in light of this ‘lack of connectivity between the brain regions of the feeding network’ it may take a longer time to communicate satiety, or even ‘pleasure’ once the food is ingested. Thus underscoring the power of this self-report trait: because it may mean that See Food Eat It translates into See Food Eat Lots (More) of It.
Clues into the neurobiology of motivated behaviour give us a unique insight into the perils of simply having too much. Here in America, food is everywhere. Thus multiplying your risk for overeating (particularly if you are high on this trait) exponentially. We respond positively to appetizing food, because it sends a clear and concise message to the brain (along those same ‘brain feeding patterns’) that something positive is happening (indeed, the ingestion of food is a positive thing: it helps us survive for longer).
Problematically, we are seeing that the desire to overeat does not correspond with our physiological needs. So, our brain selfishly overcompensates by overeating at every chance it gets. When there is less food around, there are fewer opportunities for our brains to (mistakenly) convince us that we are ‘hungry’.
In other words
No wonder the French are so skinny.
Today’s post was inspired by:
Passamonti, Rowe, Schwarzbauer, Ewbank, von dem Hagen and Calder1 (2009). ‘Personality Predicts the Brain’s Response to Viewing Appetizing Foods: The Neural Basis of a Risk Factor for Overeating’ Journal of Neuroscience, 29(1):43-51.