A recent nine-day in-patient experience with peritonitis in a French hospital gave me the unexpected chance to indulge in a 6 day severely restricted diet. An unenjoyable learning opportunity not to be missed!
After 6 days of being unable to eat anything other than broth and antibiotics I was given the all clear to start eating normal foods. It was approximately 10pm and I was on the 5th floor of Perigoux hospital, South West France. I had heavy back and abdominal pain from my serious abdominal surgery which meant I had a bottle draining my abdominal contents in my left hand and my 'trolley' containing my intravenous drip and antibiotics in my right (clip below!).
All I could think about was chocolate, and how I hadn't had any in a week. The cafe was closed and the vending machines only took euros; I had a five-pound note in my wallet and couldn't speak a word of french (still can't, shamefully after their superb care). In pursuit of my overwhelming desire for chocolate I climbed down 5 flights of stairs (with trolley, bottle and pain), searching for an open cafe and / or someone to change my pounds to euros involving significant gesturing due to the language issue.
The search took me about an hour and I returned fruitless (chocolate-less) and went to bed pretty miserable with my five quid!
A great story, or not, but the point here being I was prepared, and did work pretty hard in trying circumstances for the anticipated reward of some chocolate. I had books and fruit with me in my room, yet these did not prevent my personal crusade, I wanted more. What was going on here?
Researchers have been studying this drive for food reward for some time. They take a person and place them on a slot machine where they press a button and receive a chocolate bar when two slots line up. Then over time they only give an award when the slots line up twice, then three times, then four.....and so on. This 'work' is infinitely increased until the person eventually says 'jeez, its just not worth it'. The number of responses they are willing to make then quantifies how hard one might work for a given food. This characteristic is called the relative reinforcing value of food (RVV)1.
Essentially what happens during that moment when you place chocolate or something 'highly rewarding' in your mouth, an orchestra of brain activity including endorphins, dopamine, serotonin (amongst many others) go crazy and drive us to want to do it again, hence it is termed rewarding2.
What these studies show is that foods high in processed fats and sugars (and alternatively sweetened) are significantly more rewarding than fruits, magazines or other non food rewards.
Another interesting conclusion from these studies is that overweight people find these foods much more rewarding than lean people and that RRV actually predicts future obesity in non obese children3.
People who are overweight or obese find food more motivating than lean people do, a significant driver to eat more. Motivation to satisfy reward is stepping into the rhealm of addiction, a murky field when it comes to food but a relevent one. Guyenet (2017) describes how a persons susceptibility to drug addiction is a combination of both the reinforcing value of the drug AND the persons ability to control her craving - her impulsivity.
This concept of impulsivity ties back in to the concept of our chimp brain versus human brain earlier in this series. A person who has a highly reinforcing food (chocolate, pastry...) but is able to act against cravings will not become addicted, compared to the person who can't exercise self control plus highly rewarding food / substance and addiction may be inevitable. Is this self control something we are born with or can we work on it?
Its a tough question to answer. Eating a diet of moderation and variety is one of the most common recommendations to exercise self control but we have discussed why this so-often fails HERE and HERE. Perhaps we cannot get away from the incredibly rewarding value of foods available to us several times a day but we can have some basic rules to moderate how often we experience the dopamine and endorphin rush that we can come to depend on and crave.
Examples of foods that are typically rewarding have been described here and research has shown that by reducing how often we consume these foods means that when we do consume them, we enjoy them more4 (Recall the concept of habituation?!). Anticipation of reward is actually much more powerful than reward itself, in fact behavioural biologist Robert Sapolsky describes anticipation as the greatest driver of dopamine in the brain short of cocaine. There is deliberate method behind why those slot machines string out each reel stopping, building anticipation. What happens in the brain when you add in anticipation and less frequent actual rewards? The video below shows clearly how the dopamine dump is enormous and incredibly reinforcing. Anticipation trumping reward explains why the 'chase' is often much more thrilling in human courting than the end result....a topic for another day!
Some of the typically high rewarding foods can be seen below.
My crusade around the french hospital maybe wasn't so strange after all, my brain was simply after a dump of rewarding neurotransmitters it hadn't experienced for a while, an urge I was willing to work for to quench! This concept of highly rewarding foods explains a lot of what drives our behaviours to overeat, we come to crave this short term gratification.
When we give in to that urge and place chocolate on our tongue it is not satisfying our hunger, but merely our desire, and its often a strong one. The ability to resist this desire, or impulse is perhaps an opportunity for a few simple strategies to develop self-control (recall valuing your future self?!). To rely on will power purely over impulsivity is likely to lead to frustration as our chimp brain has been described as up to five times more powerful than our human brain. The flip side however is likely to be equally frustrating, if we never give in and reward our chimp then life in modern society could be equally grim.
The final part of this series on eating behaviour provides some simple strategies to navigate the issues discussed up to now, enjoying what you eat and remaining lean.
There are many ways to lose weight but all else being equal, a diet that is lower in reward value will control appetite and reduce weight gain more effectively than one with high reward value.
Making an epidemic of obese people was never the goal, it was simply a side effect in the race to make money. Highly rewarding foods drive us to buy more and the consequence is we eat more.
Maybe, just maybe, if we eat less of these things, don't allow habituation to occur and exploit anticipation, just how clever psychologists have done in the gambling industry in Vegas, then less could be more...
Luke R. Davies :)
- Guyenet, S. J. (2017). The Hungry Brain: Outsmarting the Instincts that Make us Overeat, Vermilion, Ebury Publishing, London, UK. P.66.
- Bissonette, G. B. and Roesch, M. R. (2016). Neurophysiology of Reward-Guided Behaviour: Correlates Related to Predictions, Value, Motivation, Errors, Attention, and Action. Current Topical Behaviour in Neuroscience, 27, P199-230.
- Hill, C., Saxton. J., Webber, L., Blundell, J. and Wardle, J. (2009). The Relative Reinforcing Value of Food predicts Weight Gain in a Longitudinal Study of 7-10 Year Old Children. American Journal for Clinical Nutrition, 90(2), P.276-281.
- Raynor, H. A. and Epstein, L. H. (2003). The Relative-Reinforcing Value of Food Under Differing Levels of Food Deprivation and Restriction, Appetite, 40(1), P.15-24.