Thursday, February 13, 2014

Mindless Eating

You think you're in control of your eating behavior-- but you aren't

In 2005, Brian Wansink's research group published a remarkable study that demonstrates the powerful unconscious influence of the food environment on our consumption (1). 

Volunteers were invited to a test kitchen to eat bowls of tomato soup for lunch.  Each person was given a bowl containing 18 ounces of soup-- but there was a catch.  Half the volunteers were given custom-made soup bowls that partially refilled as they ate, such that the soup level dropped more slowly.

At the end of the experiment, people with normal bowls had eaten 8.5 oz of soup before calling it quits-- a little bit less than a typical 10.5 oz can.  People with refillable bowls, in contrast, kept eating and eating-- only stopping after 14.7 oz of soup!  The visual perception of having more soup remaining in the bowl caused them to eat 73 percent more soup, and 73 percent more calories.  Even more remarkable, both groups reported similar levels of satiety (fullness) following the meal.

This and many other related experiments are described in Brian Wansink's book Mindless Eating, which I found quite thought-provoking despite having picked on it a little bit in an earlier post (2).  The research he presents shows that many subtle factors in our food environment influence our food choices and intake, sometimes in major ways.  Portion sizes, how a food is packaged and named, variety, and food cues are some of the major topics he discusses.  Some of this should be familiar to regular WHS readers. 

One of my favorite topics, and one I've been thinking more about lately, is the effort/resource cost of food, in other words, convenience and price.

Would you walk a mile for a caramel?

In a section with this title, Dr. Wansink offers us a one-sentence summary of a classic obesity research book titled Obese Humans and Rats*:
The more hassle it is to eat, the less we eat.
This is a disarmingly simple, yet extremely powerful statement. 

In many of my public talks, I have the audience do a thought experiment with me.  Imagine you're at work, and there's a plate of brownies (or whatever tempting unhealthy food you prefer) within arm's reach of you all day.  What's the likelihood that you'll eat a brownie?  For most people, the likelihood is extremely high.  Now, imagine you have to walk across the street and pay $6 for the same brownie in a coffee shop.  What's the likelihood you'll eat a brownie now?  Probably low.

Dr. Wansink presents a variety of findings supporting this concept.  Even small differences in the amount of effort required to eat have a large influence on consumption.  When consumption is made almost effortless, intake increases substantially.

The implications for calorie intake and body fatness are obvious.  A hunter-gatherer who has to climb a tree to obtain a small piece of fruit will require more motivation to engage in that activity than a person who has a large apple within arm's reach.  Where does that motivation come from?  Much of it comes from fuel depletion-- as signaled by hunger.  Therefore, a hunter-gatherer has to experience a greater degree of fuel depletion, and a greater degree of hunger, to be sufficiently motivated to obtain food that requires effort to secure.  When she does find food, she'll probably eat less of it, because the motivation of hunger will only outweigh the effort required to climb the tree until she's moderately full-- not stuffed.  Therefore, she'll tend to eat a moderate amount of food overall, and energy intake will be appropriately linked to energy needs.

You can apply the same thought experiment to any kind of food our ancestors would have encountered: game, tubers, nuts, honey, and agricultural foods such as grains and legumes.  It all required effort to obtain and prepare.  In affluent societies, the effort and resource cost of food are incredibly low by historical standards, due to advances in farming, food processing, and food distribution.  Therefore, we eat more.  It really is that simple, although there are other factors involved of course.

Limitations

Did you think I was going to let Mindless Eating off the hook so easily?  There are a few aspects of the book that I think could be improved.  The first is Dr. Wansink's incorrect understanding of the relationship between calorie intake and body fatness, which I detailed here (2).  This undermines one of the main thrusts of the book, which is that you can lose a lot of body fat simply by manipulating your surroundings into favoring a slightly lower daily calorie intake (~100 kcal).  Major fat loss requires a larger calorie deficit than this.

A second problem I have with the book is that Dr. Wansink likes to spin a tale a little bit too much.  The book is entertaining and accessible as a result, but there are times when the tale doesn't entirely line up with the evidence.  The most obvious example of this is in the mythbusting chapter "In the Mood for Comfort Food".  Here, he claims that it's a myth that comfort foods tend to be unhealthy, and it's also a myth that we tend to gravitate toward unhealthy foods when we're stressed or sad.  This immediately set off my alarm bells, because I frequently cite American Psychological Association data that support these concepts-- many people do overeat unhealthy "comfort" food when stressed, as common sense would suggest (3). 

The data Dr. Wansink presents in support of his "myth-busting" actually undermine his argument and support the APA data, yet he marches through them unfazed.  According to the book, the top 5 most popular comfort foods, in descending order of popularity, are:
  1. Potato chips
  2. Ice cream
  3. Cookies
  4. Candy/chocolate
  5. Pasta or pizza
Healthy or not-- you be the judge.  One important point he does make, which I agree with, is that people often eat junky comfort foods when they're happy-- not just sad.

Another thing that bothered me about the book is the frequent reliance on anecdotes and fuzzy numbers.  His group has conducted countless controlled studies, so why not focus on group averages rather than individual anecdotes picked from the study population?  This makes the book more engaging, but at the expense of accuracy. 

One final limitation is that nearly all the studies in the book measured short-term food intake, not long-term intake or body weight changes.  It's implicitly assumed that these short-term changes would translate into long-term effects on total calorie intake and body fatness, yet this isn't necessarily the case.  Peoples' eating habits can sometimes adjust to new circumstances over time, and there are additional long-term homeostatic influences from the brain systems that regulate fatness.

Conclusion

Mindless Eating is a very thought-provoking book, full of science-backed practical information that can help us design a healthy food environment.  These are important concepts, some of which are part of my core model of overweight and fat loss.  With a few caveats, I think the book is a useful addition to the repertoire of anyone who's interested in understanding eating behavior and body fatness.  It's also extremely accessible and entertaining.


* I own Obese Humans and Rats, and I don't think this is a great summary of it.  However, the concept remains correct and important.
 

12 comments:

Sanjeev said...

> was going to let Mindless Eating off the hook so easily?

the most distracting/disturbing thing to me was the facile long-term extrapolations from short term (sometimes very short term) studies.

Mostly a wonderful book though.

Robert said...

Hi Dr. G,

Thank you for this interesting post. Altering our environment to remove food temptations does seem like a low-hanging fruit solution that any dieter should try.

But this brings up the need for societal changes outside of a person's control. For example, if I "go Paleo/vegan" and remove processed foods from my house, I still have to navigate copious, cheap, tasty junk food driving to work (fast food joints), at work (coke and snack machines on every floor of our building), driving home from work (more fast food joints). And even on the weekends while shopping groceries or going to the pharmacy (Rite Aid and even Trader Joes are chock full of processed crap by the check-out isles at eye level). Not to mention the constant junk food ads on TV, in newspapers...

So personal changes in one's food environment to make food harder to get are great and will work to some extent, but larger societal changes in food zoning and marketing are needed. Thanks.

raphi said...

"you can lose a lot of body fat simply by manipulating your surroundings into favoring a slightly lower daily calorie intake (~100 kcal). Major fat loss requires a larger calorie deficit than this."

Agreed, E=mc2.
Fat mass cannot be created out of thin air.
A 200kg person cannot lose 100kg without experiencing a decrease in total energy retained within the whole body over the the time when these 2 measurements are made.
No thinking person will argue against such empirical observations that have been tested, retested, tested, retested....or at least none to take seriously.

Still...

I fail to see the utility of discussing the 'issue' in terms of total energy when it is the form & manner in which this energy interacts with our system, i.e., hormones, micronutrients, macronutrients, behavior, reduction-oxidation reactions, proton gradients, mitochondrial efficiency...the conversation is so much more enlightening & interesting with these nuances and obligate complexity are recognized rather than downplayed.

Hopefully--->to arrive at a testable hypothesis that withstands attempted destruction.

How can discussing 'energy balance' issues simple in terms of MORE/LESS 'energy balance' (calories, a unit of energy) NOT be restating the question/problem without attempting to provide further understanding...? [this is a genuine question, not rhetorical]

psychic24 said...

"When she does find food, she'll probably eat less of it, because the motivation of hunger will only outweigh the effort required to climb the tree until she's moderately full-- not stuffed"

Im missing the logic that ties this statement together because she doesn't need to climb another tree after securing the food.

Jamie Koonce said...

I'm having a hard time seeing the connection between having brownies (or other edible food-like product) conveniently available 24 hours a day and wanting to eat them. Since I have been eating a primal/paleo/ancestral diet for over a decade now, it takes absolutely zero willpower to resist the junk I used to crave when I was on a "healthy" standard American diet. Even if I am hungry, the aroma of the Kraft macaroni & cheese or the sight of a Reese's peanut butter cup don't really tempt me to eat them. Possibly this is because I know that the way I will feel after eating those products would be worse than the temporary hunger involved in waiting a few hours for "real" food. It's true that it is definitely more convenient to eat free brownies that are in front of my face than to walk across the street and pay $6 for a brownie, but what is going to cause me to crave the brownie in the first place -- especially if I don't perceive it as food?

Stephan Guyenet said...

Hi psychic,

The example assumes that there are fruit on different parts of a tree that the person must continue to climb if she wants to continue to eat.

Hi Jamie,

It's wonderful that you no longer crave junk food, but in my opinion that isn't typical. I've eaten very little junk food over the last 10 years, yet I still get cravings for pizza, brownies, chips, etc., when I encounter them. I don't miss them when they aren't around, but when they're in front of me and a catch a whiff...

It doesn't really matter whether I'm on a Paleo diet, low-carb, high-carb, vegetarian, or even vegan diet... each of which I've tried... I still want certain types of junk food if they're in front of me.

Certain things I have no desire for anymore though, like donuts and most other fried foods. They usually just taste like rancid oil to me now.

The point is that for most people, there is a desire to eat these foods that is independent of everything other than the pleasure they provide-- including hunger. This impulse can sometimes be overridden by strong cognitive aversions, and it sounds like you've successfully cultivated those (thoughts about how you will feel in the future, not perceiving it as food). So congrats-- but I wouldn't generalize your situation.

Vincent Gabriel said...

Stephan,
Thanks for another great and thought-provoking post. My experience has been similar to Robert and Jamie’s in that I simply don’t want certain foods, although I have had that cravings re-triggered from time to time if I start to eat certain things like chocolate. I may be forgetting other things that are out of my sight however. Anyway, I don’t know all the science behind food cravings, but I do know a lot about control of harmful urges from the perspective of investing where certain things that many psychologist believe are “hardwired” into our brains (like a gambling mentality) need to be overcome to be successful. It seems like if I look back on improving my diet and dropping body fat, and what I have seen in other people who either succeed or fail at improving their diet, the same things can be applied to food cravings. From what I have seen, successfully controlling or reversing cravings in widely diverse area seems to include these steps:

1. An intellectual understanding of why something is bad, and a practical, incremental steps way of addressing it
2. A withdrawal/cooling-off period of over-compensation away from the problem
3. An alternative approach that replaces the bad behavior, and creates an “anti-craving” repulsion
4. An outlet or periodic release (AKA a “cheat” but not a binge.)
5. A tangible reward, which is consistent with…
6. A self-image consistent with what you want and which you believe is achievable
Number Six I find particularly interesting and I got that when I asked a professional hypnotist if it was true that he could make someone stop smoking and his answer was, “I can’t force someone to stop smoking but I can help them develop a self-image of a non-smoker.”
I know that all of these are essentially psychological and you focus on the biological, but unless some trigger for dysregulation is found that can be removed force-ably removed from the diet, a psychological path may be required as well.
On a loosely-related point to your comment about severe calorie reduction, I haven’t seen you post anything about the down-regulation of metabolism (although I have by no means gotten through all your posts) that apparently occurs when someone significantly restricts calories. As someone who is naturally thin but who had started to develop a belly, this was something that always stopped my fat-loss attempts until I adopted Mark Sisson’s (and others’) concept of “fat adaptation” which was, at least for me, a silver bullet that gradually reduced fat stores without any sign of muscle loss, hormonal decline or the other problems that would otherwise occur a week or so into a calorie-restricted approach, so it would be interesting to hear your thoughts on how common that is and if there are other ways to overcome it.
Anyway, thanks for all of your great posts.

Sanjeev said...

>On a loosely-related point to your comment about severe calorie reduction, I haven’t seen you post anything about the down-regulation of metabolism

I don't recall a post dedicated to this but I do recall comments within posts about the adaptations like more efficient muscle activity and reduction of desire to move.

I've not been able to square this finding with the frequently noted[0] tendency of anorexia patient to exercise excessively.

[0] but I've never seen proof on what causes this, just seen the association reported

Robert said...

Hi Dr. G,

This is off-topic but a new double-blind RCT compared ancient wheat to modern wheat and found that IBS symptoms and inflammation were significantly reduced with ancient wheat. I always thought the Wheat Belly argument was bogus but these results are interesting (albeit in only 20 people, all IBS+).

If this inflammation is associated with hypothalamic inflammation...maybe gut issues are driving brain issues?

http://www.ncbi.nlm.nih.gov/pubmed/24521561?dopt=Citation

Sanjeev said...

> new double-blind RCT compared ancient wheat to modern wheat

I'm shocked the axe-grinding one has not shown up with the usual low quality "proof" (observational studies, anecdotes, reductionism, cherry picking) and the usual invalid, illogical "arguments" (trying in vain to shift the burden of proof, plain excuse-making) to try to a good Gollum impression and try to rescue, defend & "exonerate" their precioussss

Eric said...

"When she does find food, she'll probably eat less of it, because the motivation of hunger will only outweigh the effort required to climb the tree until she's moderately full-- not stuffed."

It makes sense that if food costs more effort/resources to obtain, we'll eat less, but I don't agree with the statement we'll eat less of difficult-to-gather food after the food is obtained.

Sure, the hunter-gatherer woman won't eat food that's out of reach, but once she's obtained the food, why wouldn't she eat as close to full satiation as practical?

Some of the meals I cook for myself take considerable time and effort but produce a relatively large amount, enough to last 3-4 days if I portion it out.

Except they rarely get portioned out that way. They last me 1-2 days, instead. Once the food is ready for eating, my tendency is to eat it until I'm full. The time and effort it took me to cook the food doesn't hold me back.

I regulate my meal portions by cooking smaller portions because the amount I cook is the amount I'll eat.

Honey Razwell said...

Hi Raphi,

I wanted to mention something that is my pet peeve. There is rampant abuse, misuse and gross extrapolations of the first law of thermodynamics. Doctors do it all the time.

I have discussed this very specific issue with about 40 scientists in all over the last 4 years. They are top physicists and biologists from Harvard, Cal tech, M.I.T. and elsewhere.

They all have unanimously verified what I have said :

Namely, that the first law of thermodynamics is valid for life, HOWEVER, it says absolutely NOTHING about fat cell regulation SPECIFICALLY , NOR how fat cells are governed, NOR how they respond to signalling mechanisms, NOR how they can become dysregulated.

Humans are open, non - equilibrium dissipative systems. We poop put energy and we also produce substantial amounts of dissipated heat ranging from 80 to 120 watts. Energy balance is part of it but not the whole story. fay cell regulation is NOT specifically addressed by the first law at all. It says NOTHING about fat loss specifically, or WHAT mass gets lost.

Obesity is NOT a problem of basic thermodynamics. It is extremely complicated biochemical processes and is best understood within that framework as well as physiology etc. They STRESSED this.

ACTUAL physicists and biologists are not saying what the Blogosphere gurus do.

The best of the best told me this personally. Experts in non- equilibrium thermodynamics from M.I.T. and elsewhere, including even Dr. Gavin Crooks.

Lastly, "successful" gastric bypass patients are still very fat body fat precentage wise. In human meat terms, they are still salami, not sirlion. They are only smaller in overall size, but still quite fat.Many or most look like smaller versions of their fat self. I sympathize. They are victims of dogma. The operation does not work anywhere near as good as advertised as Dr. Jeffrey Friedman points out. I have played basketball against several "successful" people and they are as soft as a pillow. I almost fell asleep forearm cheking them while they backed me down under the basket. It was so comfortable. Their backs feel waaay different than a normal never obese person. Again, I am not criticizing. They are victims of a dogmatic medical profession.

The great thing about science is that it forces us to be UNCOMFORTABLE. This is how we learn. It makes us force our beliefs to conform to the evidence of reality, NOT the other way around- or some MISUSED and erroneously extrapolated law....

People who become sc scientists generally love MYSTERY and there is PLENTY of mystery with obesity.

There is PLENTY to learn about the chemical behavior of fat cell receptors.

"Successful" gastric bypass operation patients generally are smaller pieces of salami or slightly leaner salami- all that after being starved on 800 calories a day.

The caloric hypothesis BY ITSELF is much, much too simplistic to explain body fat regulation which is highly complicated. There is MUCH more going on. Many scientists told me this who study the molecular machines of life.

Best wishes,
Raz