A High-Fat Diet may be beneficial?!

Some researchers have made the discovery that a diet high in saturated fat could impair rats' ability to inhibit responding to stimuli that are reinforced in some circumstances but not in others.  This article can be found at this link.  This is basically proposing a solution to a problem I had blogged about two weeks ago ("Learning and the persistence of appetite") where if something is extinguished in one context, the same behavior may renew and appear again in a different context (one that it was not extinguished in). The researchers are suggesting that if one consumes a high fat diet that those behaviors will be extinguished for good and will not reappear in a different context (= renewal will not occur). At first glance this sounds preposterous, as it certainly did for me, but if true, the applications are tantalizing. The main examples I think of with extinction and renewal are fear conditioning, extinction of overeating habits, addictions, etc. Imagine if one could finally extinguish these conditions in one setting and have them permanently extinguished and remain that way in other settings as well.
    Rats were trained in two contexts, X and Y.  They were trained to consume sucrose pellets as reinforcers in two 64-minute sessions with 16 deliveries of two 45-mg sucrose pellets.  Then, the rats received training with an auditory cue; in each of eight 64-minute daily sessions rats received sixteen 10 second reinforced presentations of an 80-db white noise.  After the acquisition training, half the rats were fed the high fat diet and half were fed the control diet for 7 days.  After this phase, rats were kept on a calorie restriction for 7 days, so that they would be motivated for the extinction training.  Finally, the rats received extinction training with 16 non-reinforced presentations of noise; half of the rats received extinction in the same context in which they were trained and half received extinction in a different context.  The extinction was done with the introduction of a light, which preceded the tone CS, and signaled no food coming.  Finally, all the rats returned to the same context and were given four daily tests of renewal of extinguished food cup responding.    Responding by the rats was measured as the amount of time they spent with their head in the food cup before or after the time of reinforcer delivery.  The results showed that control rats extinguished in a new context showed renewal back in their training context, while rats who were fed a high-fat diet showed considerably less renewal.  Therefore, it was concluded that exposure to a high-fat diet reduced the context-specificity of extinction.  

An interesting point that the discussion section brings up is the possibility that a high-fat diet may be interfering with normal hippocampus and medial prefrontal cortex learning.  They are suggesting that these areas of the brain may be affected, thus leading to a lack of contextual control.  This, in turn, is encouraging people to overeat because they ignore the normal cues such as internal satiety signals or external signals (predators is the example given); just like the rats who ignored the light signals that food was not coming.  This point actually counters my original thought that overeating could somehow be extinguished (by extinguishing the cues and CS's that cause humans to expect food) and transferred over to multiple settings.  In addition to explaining overeating, this article may be helpful for therapeutic extinction of anxieties and fears as well.  Imagine a scenario where a fear or anxiety is extinguished in the therapist's office, but rather than renew and reappear in other contexts as these things tend to do, they remain permanently extinguished.

    I want to make some critiques of this article that came to my attention as I was reading it and speaking to my professor.  What if the rats are simply nosing around the food cup extensively because they like the high-fat food so much and get addicted to it, just as someone gets addicted to candy or potato chips, etc. which are also high in fat.  Maybe they choose to ignore the extinction cue of the light simply because the reward (fatty food) is so tantalizing and they can't get enough of it, so they are always in search of it.  
    An issue that was brought to light in my discussions with Professor Blaisdell was that rats and humans digest fats very differently, which may be the key to the differences in the effects of fats between the two groups. It is well-known that a diet high in fats can cause all sorts of complications in humans such as cardiovascular disease, obesity and an impairment of cognitive functioning, but apparently in rats it shows some positive effects of countering extinction. Lard (pig fat) has a high concentration (almost 50%) of monounsaturated fats, which can be digested better in rats than in humans.
    With careful reading of the 'materials and methods' section you can see that there is a disproportionately larger amount of corn starch in the control group as opposed to the high-fat diet group (452.2g vs. 72.8g). Corn starch is a thickening agent, and I wonder if they had to use extra corn starch in order to counter the lower quantity of lard (maybe to give the two groups' foods similar appearances) and if it had any effects on the results of the experiment. In addition, I noticed that there is 20g of lard in the control group as opposed to the 177.5g in the HFD group, which makes sense considering it is a control for this factor, but the researchers never controlled for the amount of kcal/g in the two groups.

Regardless of the critiques of this article, it is an interesting find and definitely something worth blogging about and bringing to the attention of others.  If something along these lines can be replicated in humans then, needless to say, it will change the way we think of high-fat foods and may end up appreciating the benefits, especially in a therapeutic setting.

Shangri-La Diet: What people have to say about it.

      I am going to deviate from the norm of blogging about primary literature on research articles and dive into a diet regimen introduced and extensively elaborated on by Seth Roberts.  As a disclaimer: I am not recommending this diet; it is something that should be looked at and analyzed, however.  Also, I have not read the full text of The Shangri-La Diet and what I am going to write about stems from online research, particularly from the author's website itself, Sethroberts.net.  I am going to look into what the Shangri-La diet actually is, how it relates to Psychology and what things people are actually saying about it.  The website I got most of my information off of can be found at SethRoberts.net.

      Let me start off with a quick background about the Shangri-La diet.  Roberts believes in a “set point” theory of weight control: at any given time, your body wants to be a certain weight, and it will increase or decrease feelings of hunger and its metabolic rate in order to achieve that weight. Any attempt to modify your weight away from your current set point will meet with failure, or at least will be very difficult to achieve and maintain. Roberts compares the set point to the temperature setting for a thermostat.  The set point idea is not new, but Roberts extends it by claiming that the set point can be modified by diet. This is the second part of his theory: the “taste-calorie association.” Roberts believes that the “tastiness” of the food you consume controls your set point. Specifically, tastier food raises your set point (i.e., makes your body want to get fatter), while bland food lowers your set point (i.e., makes your body want to adapt to being leaner).  According to calorielab.com, the three major ways of breaking the taste-calorie association is to: consume calories that have little or no taste, consume calories that have an unfamiliar taste, consume foods that are only detected by the body after a delay (in order to dissociate the initial taste from the later calorie hit).
     One of my earlier blog posts was also about a taste-calorie association and about how rats would eat more when given a tasty, calorie-dense food because that is how we have come to associate and enjoy the two together.  Seth Roberts talks about different techniques of breaking the taste-calorie association and suppressing appetite.  The consumption of oils is one thing I came across (in my readings of people's experiences) as a successful technique.  Drinking a spoonful of olive oil or canola oil twice a day seems to work in suppressing appetite; people report eating less in a meal after they have consumed olive oil.  Seth Roberts recommends drinking the spoonful of oil an hour before or an hour after the meal, long enough so that a connection is not made between the food and the oil, however.  The oil is tasteless and relatively odorless and you are still consuming calories (about 200-300 a day), but not associating it to any particular taste or smell in your brain and thus not reinforcing those connections that have been made between taste and calories.  One of the reasons why we eat so much is because we feel good after we consume those calories because of the pleasurable associations we have created in our brain between tastes/smells and the foods we consume.  By consuming tasteless things like oils, people are cutting down on the amount of food/calories that they want to take in and this reduces junk/snack food consumption tremendously.  Another technique to suppress appetite is to drink vinegar-water before a meal.  Although that sounds pretty disgusting, it has a purpose in aiming to suppress appetite and prevent you from overeating (and especially snacking on junk and desserts after your meal) which is a big cause of weight gain.

    When reading the experiences of a first time user of the Shangri-La diet on her first day, I became intrigued at the immediate impact this diet has.  The user said she skipped breakfast and had no appetite to eat and was only getting full off of half a sandwich, some chips and maybe a fruit later on in the day.  It is amazing how changing your daily regimen can cause you to lose drastic amounts of weight, as some report losing averages of 2-3 pounds a week over the course of months.  

     There is a discussion about bland, unprocessed foods compared to processed foods.  The idea behind this is that processed foods have been added with so many tastes including spices, salts, fats, etc. and that every piece of the processed food tastes the same, in any part of the world, that our brain recognizes those tastes, makes the associations with calories and we eat it non-stop.  Things like salts, fats, sugars are tastes that we are genetically wired to eat because they signal that we will get full off of that meal (by ingesting calories).  These were cues that our ancestors used to know if a food was going to fill them up or if they were going to starve.  And now in the 21st century, these are the same cues that are signaling to us that the foods are full of calories... but since food is so abundant in this day and age we end up overeating.  The blandness argument makes sense because we are not going to immediately recognize the calories that we are ingesting and therefore, not overeat.  In many ways, the taste of the food is acting as a conditioned stimulus that signals the unconditioned stimulus - calories.  By breaking that association, or messing with the association and introducing tasteless or unfamiliarly tasting foods, then we are breaking the CS-US association and we are less likely to eat as much.
     In conclusion, the real successes I see behind the Shangri-La diet are that you do not need to restrict the foods you eat or have an insane amount of will-power in order to keep up the weight-loss or maintain your progress. With the suppression of appetite, you won't feel like eating any more and you will be more inclined to restrict the amount of calories that you consume.  As some people posted about, they can still have their cheese and ice creams, but they're not mindlessly eating two bags of M&M's in one sitting at the movie theaters, but rather something like half a bag and being just as satisfied.  Humans are intellectual beings that learn and form associations between millions of things.  Taste, calories and appetite are just a few examples of the things we make associations between and can learn to break and manipulate!

Learning and the persistence of appetite

This week's blog entry is about the most interesting article on eating and learning that I have read up to date. You can find it here.  Unlike my previous posts, it is not based on a specific research study, but about the work of behavior psychologist Mark Bouton, who aims to reach far-ranging conclusions and analyses about various observations and phenomenon that have been encountered with learning and extinction of appetitive behavior.  I was hoping to drift slightly from the extensive blogging about Pavlovian conditioning and move unto a topic that was more recently discussed (in class) - operant conditioning, appetitive behavior, and the return of extinguished behaviors.  To start off - appetitive behavior is a behavior that increases the likelihood of satisfying a specific need (something pleasant), and is a central component of operant behavior.  Extinction is a conditioning phenomenon as well, where a previously learned response to a cue is eliminated when a cue is presented in the absence of the previously paired aversive or appetitive stimulus (Wikipedia.org).
    I wrote an earlier blog entry about how environmental cues are so important in our lives and how they can trigger an eating response, even if we aren't hungry.  This article gets into the effects of extinguishing those learned responses; and how extinguishing those is simply context-specific, likely to resurface when the environment changes.  It has been found that extinction does not erase the original learning, meaning that it is hard to unlearn behavior and habits that have developed over many years, but someone may learn that a CS or behavior is no longer paired with the reinforcer only in the present context.
    The first, major point that is hit upon is renewal of extinguished appetitive behavior.  Simply put, if a CS is associated with a reinforcer in one context (Context A) and then extinguished in a second one (Context B), the CS elicits the behavior again when it is returned to the original context (Context A) or a new context (Context C), these are referred to as ABA renewal or ABC renewal, respectively.  This tells us that simply removing some organism from the context of the extinction will reinstate the conditioned response.  This is a scary thought for people being treated for anxiety disorders or for conditioned fear responses.  The current technique I know of for extinguishing fear and anxiety in patients is exposure therapy.  Patients are exposed to the object or a less threatening form of the object that they fear (void of any actual danger) in slow, successive steps.  For example, someone who is afraid of snakes will be shown pictures of snakes, then touch rubber snakes, then be in the presence of a real snake, then potentially touch a real snake.  This research is suggesting that once that even though the conditioned fear is extinguished, the patient will once again be afraid as soon as he steps into the original context where he learned the fear (like the snake exhibit at the zoo) or in a context different from the therapist's office.  Since my blog is focused on health and eating, I will also give an example of the return of an extinguished behavior and overeating.  Friends of mine at UCLA who actually live there (I am a commuter, so it is not AS STRONG in my case) tell me how happy they are that they have stopped overeating at school and have begun working out and getting in shape.  They were notorious overeaters in their hometowns and were overweight, but have since learned to cut back on their desire to overeat.  When they return home for the holidays, however, that extinguished response seems to reemerge they tell me, as they indulge in the feasts presented during Thanksgiving, Christmas, Easter, etc.  The interesting thing, though, is that they were not just taking advantage of the holidays and rewarding themselves with lots of food and desserts for a great quarter at school.  For the duration of their vacation, they were actually reverting to their old "pre-extinguished" way of life, and unable to preserve their patterns of healthy eating and working out.  In other words, they were able to stop overeating in the setting of UCLA, but were unable to transfer that behavior over to another context that they had not trained themselves in.
    The other, important topic I wanted to dive into is the resurgence of extinguished appetitive behavior.  Bouton talks about this in terms of learning one operant response (pressing a lever in a Skinner box) and then, while that behavior is being extinguished, a second, replacement behavior is reinforced (pressing a second lever in the box).  In a third phase, the second behavior is then extinguished, and the first response recovers.  The extinction in this case is not erasing the original memory, but only suppressing it.  I have experienced similar, in my own life, with the reinforcement of "other" behavior during the extinction of a target behavior.  During the summer after 10th grade, while I was 15 years old and looking to start working out, I experienced this exact thing.  I was a little overweight and decided that I was at the right age to get myself a gym membership... so I did.  I was taking one summer class at Santa Monica College and going to the gym after class, every day.  I was extinguishing my regular behavior or overeating and replacing it with a new, reinforcing behavior of working out.  So now, rather than getting pleasure from eating, I was getting pleasure (reinforcement) from working out, and even eating less reinforcing and pleasurable foods (such as vegetables instead of junk food).  I felt myself losing weight, I was building muscle tone and feeling pretty good about myself.  This continued for months (so you would think it would stick pretty strongly with me) until school started and my workload in high school became hectic again.  I was taking 3 AP classes, the rest of them honors classes, and the extra time that I had to dedicate (to the gym) shrunk drastically.  I was no longer able to utilize my YMCA gym membership 5 times a week as I had done during the summer, but was now going maybe once a week if I was lucky and not building muscle nearly as efficiently or effectively as I had done before.  As Bouton puts it, once that secondary behavior becomes extinguished, it could allow the bad habits to resurge... and they did.  I began overeating again to counteract the stresses of school and I was not able to get the reinforcement from working out at the gym any longer.  It is as if my original behavior had not been extinguished, and had suddenly resurged onto the surface.
   With the examples that I have given above, it is important to note a few things as take-home messages.  Extinction is not the same as erasure; the tendency to respond can return at any time.  Sometimes just by changing the context (ABC renewal), or the passage of time (Spontaneous recovery), a behavior that was thought to be extinguished and erased could end up resurfacing.  Also,  conditioning generalizes more than extinction does to a new context.  So just because you extinguished a behavior does not mean that there will not be resurgence if someone is placed in a different environment.  It also turns out that the second thing learned about a stimulus is often more context-specific than the first thing learned.  It is as if the memory system treats something that is learned second as conditional, context-specific and an exception to the general rule that reinforcement will be occurring.  Extinction is thus context-specific because it is the second thing learned.  Renewal, spontaneous recovery, and resurgence all tell us that lapse and relapse are very good possibilities (and perhaps inevitable) to see after extinction.  This can explain why once a behavior is learned it is so persistent.  This also tells me why the behavior of overeating is so hard to extinguish (in my case of replacing it with working out, or my friends case of coming to UCLA and training to eat healthier) when it has been a common part of your life for over a decade.

Aversive images and Evaluative conditioning in food choices

     This is the third installment of my weekly blog post; and I am running through the longest article, up to this point.  The article is here for anyone with access.  The title of the article is "Using aversive images to enhance healthy food choices and implicit attitudes: An experimental test of evaluative conditioning" and I'm excited to talk about the real-world applications that this study portrays.  Let me define some terms, just to help clarify the points of the study.  Evaluative conditioning deals with how we can come to like or dislike something through an association (Wikipedia.org).  So basically, evaluators wanted participants to form an association between energy-dense snack foods and aversive images.  The evaluators also wanted to see how this evaluative conditioning would affect implicit attitudes - the positive or negative thoughts, feelings, or actions towards objects which arise due to past experiences which one is either unaware of or which one cannot attribute to an identified previous experience (Wikipedia.org).  [Later on I will talk about the problem I see with this definition of implicit attitude and the experiment].  They would assess this using the Implicit Association Test (IAT) which required participants to choose between fruits or snacks to take home with them.
    The experiment was conducted with 134 participants (101 females) who were recruited from King's College London staff and students.  Participants were randomly assigned to either a control or intervention group which determined what set of pictures they would be viewing.  Participants were asked to watch a slideshow of 100 images (five snack images shown 20 times in a random order).  Each trial lasted for 2.5s, with the snack image being shown for one second, followed by one of five aversive bodily images (intervention condition) or just a blank screen (control condition).  The aversive images were carefully chosen through pilot participants and came to include two images of obesity (in men and women), two images of arterial disease (with the text "artery disease" written on them) and one of heart surgery.
    Two outcomes were measured.  The primary outcome measure (an index of behavior) involved participants choosing to take fruit or snacks home with them and secondly, a voucher to spend at either a fruit or confectionery stand at the nearby train station.  The participants' choices were scored on a 5 point scale from -2 (two choices of snacks) to 0 (no preferences either way) to +2 (two choices of fruit).  The secondary outcome measure dealt with the IAT.  The assumption with the IAT is that responses to categories that are highly associated in memory are assumed to be faster when they share the same response key, relative to the response to categories not associated in memory.  Four categories were laid out, as two targets (fruit, snacks) and two attributes (pleasant, unpleasant).  So, in a first task, participants assigned a target with an attribute, so they would assign "fruit" and "pleasant" to the left computer key ("E") and "snacks" and "unpleasant" to the right key ("I").  In the second task, the targets were switched, so the left key was for snacks-pleasant and the right key for fruits-unpleasant.  Then, category headings were displayed throughout, in the left and right hand corners of the screen and participants had to press the correct button that corresponded to them.  Errors in sorting were pointed out, and an accurate response was necessary to move on to the next presentation.  The IAT scores were measured as the average response time between the two versions of the critical combined task.  In other words, if responses were faster for when fruit-pleasant were on the same key (than with fruit-unpleasant), then that must have meant that an association had been made in the mind of the participant and a more positive score would be assigned indicating a more positive attitude to fruit, and a more negative attitude to snacks.  In addition, explicit attitudes of the participants were also measured.  Participants were asked to express their ratings to "For me, eating fruits/snacks is" along 5 semantic differential scales (not at all healthy - healthy; bad - not at all bad; not at all enjoyable - enjoyable; not at all unpleasant - unpleasant; good - not at all good) and their responses were scored to gauge their overall preference for fruit.
     The results of the experiment showed that with the primary outcome, participants in the intervention condition preferred to choose fruit over snacks more often than those in the controlled condition.  This was predictable, since those in the control group were simply seeing biscuits, cookies, brownies, etc. with no association or link to them being healthy or unhealthy.  Those in the intervention group had made an association between the aversive images and the snacks and decided not to choose them when given the chance.  With the secondary outcome (test of implicit attitudes) it was shown that there were higher IAT scores  than in the control group, indicating a relatively stronger implicit preference for fruit over snacks.  In addition, both the implicit and explicit attitudes explained the variance in food choice that was observed.  Results were always compared to a baseline in the pre-intervention to see how participants' choices had changed.
       One potential problem I see with these results is that there was an overwhelming majority of females in the study who may be more likely to change their attitudes and select healthier snacks, because of an underlying preference to eat healthier. Also, since this study was conducted at a College, it is not representative of the general population and may include participants who are generally more health-conscious and more likely to change their behaviors and eating habits as opposed to older individuals who may be more fixed in their eating preferences and behaviors.  Another problem with the study may be the lack of controlling for the aversive images.  Maybe it is the aversive stimuli that are causing the participants to choose one way or the other.  Ideally, a control group should be established with participants exposed to just the aversive stimuli and see how they respond, or even a control group where fruits are shown with the aversive images to see if participants would prefer to choose the energy-dense snacks over the fruits that were associated with aversive images.  These would, potentially, make the experiment a lot more valid and convincing, but there are always costs of money and time associated with recruiting more participants and sorting through the data from all the various experimental conditions.  Another point to note in this experiment (not necessarily a problem) was that there was an inability to change the implicit attitudes of those who already held negative attitudes towards the snacks, which could be explained by ceiling effects.  As explained in my psychology class, ceiling effects arise when responding to a certain stimulus has already reached its maximum potential, and you are not going to get any increase in responding, as if you had hit a ceiling.
     It is interesting to note that in this experiment, the conditioned stimulus (CS) is the food, and the unconditioned stimulus (US) is the aversive images of health consequences (obesity, arterial disease, etc.) This is reversed, where normally we would see food as the US in other experiments because it is enjoyable and biologically essential, and elicits an unconditioned response.  The results of the experiment did not say a lot about how explicit attitudes were changed in the participants, but it is noted that implicit attitudes, rather than explicit attitudes have been shown to be changed through the evaluative conditioning when there is a clear, observable link between the CS and the US.  In this case there was that strong association between the CS and the US, which is why we saw a large change in implicit attitude in those participants who had stronger implicit preferences for snacks over fruit at baseline.
     When I first read through this experiment, I immediately connected it to the real-world applications of advertising and marketing.  Imagine billboards with images of sodas and aversive images of obese adults on them, along with a message saying "GOT MILK?" on the bottom?  The possibilities are endless with conditioning people to associate two images and change implicit attitudes to the foods/drinks that they previously enjoyed so much.  The study itself talks about aversive images used on tobacco packaging (the skull and bones), signaling how this procedure is already underway and will potentially become more widespread as more research is conducted and experiments begin to dive deeper into the underlying mechanisms of behavior change and the best methods of intervention.  I believe that implicit attitudes are not going to be changed overnight with a simple experiment linking foods and aversive stimuli; because, even in this study, people are clearly going to remember that they saw hundreds of aversive images next to the snacks that they were later asked to choose from (it is not like they don't remember their past experience, and they suddenly feel a change in their behavior).  I believe that implicit attitudes are much harder to change in most people who already have established food preferences and behaviors.  This is why I believe the research should have been conducted on more adults.  Potentially, the best way to prevent people from choosing energy-dense snacks over fruits is to instill a mind-set from an early age.  If people are exposed to aversive stimuli and develop a fear response to certain foods and the possibility of developing obesity and arterial disease, then they will be less likely to choose these foods over healthier alternatives.  This brings up ethical issues, however, about manipulating younger children and mentally affecting them (with aversive images), when they are most impressionable.  A whole range of convincing research needs to be conducted in order for the full effects of these advertisements to be known and eventually proliferated.