Addicted to “Food Addiction”

I recently wrote a short article on “food addiction” for the Risk Innovation Lab’s CrisBits blog (collaboratively published by Arizona State and Michigan University!). This piece mainly focuses on the scientific side of the issue- I really wanted to broadly cover research on the topic, since so many popular articles on food addiction focus on singular studies (and end up being extremely misleading). Yet I also really wanted to address the topic from an anthropological perspective.

… the notion of addictive foods attracts us on a much deeper level as well

So why are we.. almost addicted to the belief that “food addiction” is a thing? If you read my CrisBits article, you’ll see that there is (as of now) no actual evidence for any food ingredients causing addictive-like responses in humans. The field is highly debated, though: there’s plenty of scholars arguing pro and against. On top of that, the media often does a horrible job sensationalizing food addiction research (well, I suppose it does a great job sensationalizing, but a horrible job communicating the results correctly). All of that can surely create the illusion that science actually supports the food addiction theory. However, the notion of addictive foods attracts us on a much deeper level as well…

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The allure of addictive foods

There is a strong cultural appeal in the idea that certain “bad” foods or their components can cause dependence and are thus dangerous (e.g. MSG, casein, gluten). This view of overeating as addiction includes the need to “detox” and instead eat a “clean” diet (e.g. this: The Diary of a Sugar Addict in Detox).

These are not just modern health trends, but a manifestation of a need to understand our world by imposing structure and thus meaning on the untidy experience that is reality. Structure is created by categorizing things into clean/unclean, healthy/unhealthy, pure/dirty- and things that don’t clearly fit into such categories are considered unclean and dangerous. Anthropologist Mary Douglas makes this point in her seminal book, Purity and Danger, as she examines food taboos (cultural rules about what not to eat). Douglas points that prohibited foods are considered “polluting” because they defy easy classification into culturally important categories. The current unease with genetically engineered foods is a fantastic modern example: as a technology that blurs the lines between natural and unnatural domains, it is indeed often termed by opponents as “genetic pollution” or “contamination”.

…prohibited foods are considered “polluting” because they defy easy classification into culturally important categories.

The categories we create to make sense of the world have strong moral overtones, as they allow us to essentially define right and wrong. Indeed, the word “addiction” itself is connected to the moral disapproval of socially undesirable behaviors (e.g. drug abuse). Psychologist Paul Rozin points out how the fear of sugars in American diets, for example, reflects the Puritan belief that things that are very pleasurable must also be bad.

Religious Scholar Alan Levinovitz also emphasizes that people frame eating in terms of morality and religion. He discusses how concepts of healthiness reflect the “myth of paradise past”- the idealistic belief that things were better, healthier, and even morally superior before. From such perspective, novel changes to foods represent our fall from grace- whether via agriculture (e.g. as in paleo diet ideology) or industrialization and technology (as with processed and genetically modified foods).

So, that’s my little anthropological view of food addiction beliefs as a cultural phenomenon. Hope you enjoyed it!

P.S. You might see news reports on studies about food addiction.. but keep in mind that no clinical diagnosis for “food addiction” exists, and most such research uses a self-report questionnaire: the Yale Food Addiction Scale (YFAS). This tool uses DSM-IV’s generic criteria for substance abuse to measure addictive-like eating.

Most importantly, it does not validate the existence of “food addiction” as a true disorder (DSM diagnostic criteria is intended for trained clinicians, not a checklist for self-diagnosis via a simple questionnaire). This is a critical issue to consider, as most food addiction research with humans is based on diagnosing food addiction this way.


Cognition paper published!

Ta-da! Finally. Mine and Dr. Hruschka’s paper is finally out in the Journal of Cognition and Culture. This survey work was done over 2 years in both Eastern Europe and Southwestern U.S. So glad to see it in print!

HERE is the PDF: CognitiveDifferences_Paper2017. Also, if you don’t feel like reading it, i just recorded a 5-minute overview of the paper (recorded between meetings.. after 2 cups of coffee.. sorry if I talk quickly!).

Meat, Plants, and Humans..

This week on ASU campus I managed to attend a fascinating talk: Reconsidering the Role of Plant Foods in Hominin Diets by Dr. Chelsea Leonard. Screen Shot 2016-02-17 at 11.41.44 AM

It was a job talk for the Evolutionary Anthropology department here at ASU and Dr. Leonard is an evolutionary ecologist interested in “human foraging decisions & diet reconstruction”(so- her work would help to clarify what humans ate in the past!) working with Twe populations in Namibia (southwest Africa).

Why does Dr. Leonard study the role of plants? Since shifting towards more meat in diets of early humans has been suggested to be crucial for the unique adaptations in our genus (e.g. large brains), animal foods appear to be very Screen Shot 2016-02-17 at 12.00.04 PMimportant. There is indeed a strong case for meat in a human diet- in comparison to chimpanzees who are mostly herbivorous (eat plants), the human gut has opposite proportions- our small intestine is much longer, while the colon is a lot shorter. The colon is where fiber fermentation occurs- something crucial if you are eating lots of plant foods (and wild plant foods are very high fiber!). What Dr. Leonard suggests, though, is that meat’s importance in human diets may be quite overstated (especially in meat-heavy “paleo” diets popular now).

The people she studies- Twe- are “forager-horticulturalists”; while the Namibian government has been providing maize for them (this started very recently, in the last 7 yrs or so), they mostly forage for wild foods and have very low intake of animal products. Apparently, historically this population hunted large game and had a higher meat intake.. but the area is very poor in large animals now (and has been this way for ~200 yrs).

While I wont’ be able to describe everything Dr. Leonard discussed, I found the following fascinating.. Based on her observations and interviews with the Twe, she constructed and analyzed a hypothetical (yet realistic) diet for this region. Since Twe seem to be doing just fine health-wise with an extremely low animal food intake (there might be some birds, insects, rodents eaten from time to time), she wanted to test if their meatless diet truly meet basic nutritional requirements. FullSizeRender 9

Based on the plants the Twe regularly eat, her analysis showed that such meatless diet can realistically provide enough protein (it can reach minimum levels of essential amino acids our body can not produce without foods that contain them), it can also provide enough fat (while most plant sources were extremely low in fat, the grass seeds often eaten are rather high in it). The main issue with this meatless diet was calories. Getting enough calories to survive would be improbable : while the hypothetical food intake reaches 1774 calories a day.. only 772 of them are metabolized. What this means is that a lot of these calories are not available to the human body- since humans can not ferment fibers very efficiently, a lot of this rough wild plant fiber is indigestible and does not provide our body with energy.

The main issue with this meatless diet was calories.

Since foraging for wild plants  is very labor intensive (and this does not really mean standing around picking berries, but e.g. digging up roots that are about 1 meter (~40 inches) into the ground, or grinding grass seeds and cooking them into porridge), there isn’t enough time in a day to get enough digestible calories from foraging. So animal products are more efficient and provide a concentrated mix of not only essential nutrients, but fat, protein, and calories. While the speaker couldn’t quite estimate the % of calories coming from small game (the birds, insects, etc.), it was very small but still was a part of this population’s diet [note: any time honey was available, it was eaten in large amounts and rather adored, apparently!]. Thus, while a  vegetarian diet can be maintained in our modern world with plentiful food supply (and supplementation), it was not possible for non-industrialized populations.

humans are highly adaptable as we span huge geographical areas, and thus no single “diet” “made us human”

We know humans are highly adaptable as we span huge geographical areas, and thus no single “diet” “made us human” (thus, there is no one Paleo Diet). Yet plants are extremely important in our history- we see that they can sustain populations in good health to a very large degree. One issue with studying the role of plants in human diets is that they do not last well archeologically (e.g. it’s much easier to find evidence of large game being consumed, because their remains last well).

while a  vegetarian diet can be maintained in our modern world with plentiful food supply (and supplementation), it was not possible for non-industrialized populations.

Overall, this was a really great talk! It also reminded me of a paper I read on the significance of plant foods in human evolution, which I talked about HERE.

[note: if you are an evolutionary anthropologist sand have any edits/clarifications to my post, please comment! I am not an evolutionary anthropologist :)]

5000 anthropologists walk into a bar..

The annual American Anthropological Screen Shot 2015-11-29 at 12.57.33 PMAssociation (AAA) meeting has ended! This is my 3rd year attending and it is still as crazy, overwhelming, and fun at the first time. 🙂

The 2015 meeting was in Denver, CO (gorgeous gorgeous city! My first time there) and I wanted to write down a couple of impressions and things learned from this year’s event.

SO, first of all- what I presented on.. This September I began collecting my dissertation data. I also got accepted for a poster session for the Anthropology Society for Food & Nutrition at the AAA, thus I knew I’d better have an interesting poster ready by mid November. :S

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Finishing up interviews while in Finland!

It was rushed & stressful (when is it not?), I had to put together the poster & print it from Finland (I was traveling constantly before the AAAs!) but it got done.

My poster showed some preliminary results of how people (from mostly urban southwestern US) talk about healthy eating. I mostly focused on results from the pile sorting interview (presenting visual “maps” of how the 42 cars people sorted can be represented in 2 dimensions when averaged over 30 participants). I also talked about the several distinct “theories” of healthy eating that emerged from the interviews (using Q sort agreement rankings). I got good feedback and some very crucial suggestions for further work!

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Two hours of poster talking! :S Exhausting but great.


Of course, I also attended a bunch of amazing talks! Some of my favorites are summarized here:

  • Dr. Hruschka’s talk in the Environmental Anthropology session was one of the best (he is also my PhD committee chair :P). In his presentation, he mentioned the highly fashionable explanatory model called the reverse gradient. This is an observed pattern in the US (& other high-income countries) where poor women have higher levels of fat (on average) than women who are more wealthy (this is reversed when compared to the REST of the planet, where increasing resources correlate with increases in body weight).

    Many assume it has to do with poverty and not having time and resources to eat well and exercise. But actually, a great deal of data supports a different explanation: the body capital hypothesis. This hypothesis proposed that the anti-fat discrimination in marriage and jobs actually limits the economic mobility of people (particularly females) who have more body fat. So- husbands and employees seem to discriminate against heavier women.
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  • Another cool talk I heard was by Dr. Tamar Kremer-Sadlik (UCLA) who looked at the “ecology of eating perspectives” or the context in which eating takes place. Her study video recorded typical dinners in US and French families. They noticed that the existence of courses (so like a salad, main dish, dessert) reduced competition between foods and resulted in kids eating more vegetables. In other words- if your dinner table’s meal structure has few divisions into course (US families tended to have a single course + dessert, so all foods were served together), the presence of vegetables an be easily overshadowed by everything else available. In order to “share” a meal, you need to collaborate- if you have a single course, that collaboration exists whether you specifically eat the vegetable part of the dish or not (as you take some of the food offered).

    In the French family dinners, they saw a lot more division into courses (starter, main, salad, cheese, yoghurt and fruit). To be collaborative during each course, one has to eat some of whatever is served at each course. If most of the courses include vegetables, the kids would overall eat a lot more vegetables over dinner. To quantify this difference: 47% of American kids didn’t touch vegetables, while only 10% of French kids didn’t.
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  • One last fun lecture I went to was called “Pet Ownership as Cues of Character” by a group from University of Colorado Springs (Evolutionary Anthropology session). They began by saying that many studies have found that women and men attenuate to cues of attractiveness differently: women seem to pay more attention to cues of character os success. For example, one study showed that women rated men paying positive attention to an infant as more attractive, while men did not rate photos of women differently (whether they were paying attention to infant or ignoring it).

    So this group hypothesized that perhaps women conflate cues of parenting ability into attractiveness. They tested it with pet ownership, instead of having a baby! They asked US respondents to rate photos of individuals in 3 scenarios: paying attention to a dog, ignoring the dog, and a neutral/reading book photo. To their surprise, they found that only MEN rated women as MORE attractive and as MORE desirable partners when shown the photo where women pay positive attention to the pet. Women were not rating males with pets as more attractive. While the study could have some important flaws, that’s a pretty cool and intriguing outcome.

There were a LOT more talks I found fascinating, but it is too overwhelming to mention them all 🙂 #AAA2015

Till next year!

The Sci Files #1: Importance of Carbs in Human Evolution

Note: This Fall I decided to attempt even more science communication! The Sci Files (imagine the x files theme playing) will be a collection of health & food-related research articles that I summarize in plain(er) language. I became quite passionate about breaking down hard-to-understand research for the public audience and I’ll try to do my best, considering I’m no expert! Yet 5 years of graduate courses- statistics, research methods, nutrition psychology, evolution & medicine- at least give me skills to understand a lot of the material that might be overwhelming to a lay reader. I will try to keep the summary to one page (~500 words), possibly followed by extra material that could be interesting 😉

For the first Sci File, i’m looking at a paper discussed yesterday during a lecture on the paleolithic diet. It’s published in 2015 in The Quarterly Review of Biology and the title intrigued me “The Importance of Dietary Carbohydrate in Human Evolution”. I’ve heard multiple talks on how the various “paleolithic” diets could have included starchy foods, but I didn’t think they were substantial parts of such diets.
Original paper: Hardy, K., Brand-Miller, J., Brown, K. D., Thomas, M. G., & Copeland, L. (2015). The importance of dietary carbohydrate in human evolution. The Quarterly Review of Biology, 90(3), 251-268.

Short summary:  

Apparently, you can delete the “NO” and still keep calm 😉

The authors propose that carbohydrates- particularly cooked high starch plant foods like tubers & roots- were essential in the evolution of our species- especially for the quick expansion of the human brain. They support this by showing that (1) critical development of this large glucozse-hungry organ required digestible carbohydrates, and eating cooked starch would really increase this energy availability to the brain (+ other glucose-hungry tissues such as red blood cells and the developing fetus).

They also show that the mutation in the enzyme for digesting carbs (salivary emylase, AMY1) co-evolved with both cooking and eating starchy carbs, giving an advantage to early humans. To put it in simpler terms: carbs were quite important, as shown in our increased ability to digest cooked starch (otherwise, why retain this mutation if we did not rely on cooked starches for a substantial amount of time?). A meat-heavy diet wouldn’t have provided sufficient glucose or energy to the growing brain + 1) large amounts of protein are in fact toxic and 2) providing sufficient amount of animal-based food would require too much effort:

“the energy expenditure required to obtain it may have been far greater than that used for collecting tubers from a reliable source”

Some Context: 

There is no clear agreement on what constituted a “Paleolithic diet”, but it makes sense to assume that our current physiology should be optimized to the kind of diet we had during our evolutionary past. Some important features in our evolution are considered linked particularly to key changes in diet: smaller teeth, smaller digestive tract (1.8 mln years ago), larger brain size (began ~2 mln yrs ago; accelerated around 800,000 yrs ago), and better aerobic capacity (ability of the heart and lungs to get oxygen to the muscles) about 2 mln years ago.

Early hominins include modern humans, extinct human species, and all our immediate ancestors

Some have argued that these changes happened because  humans transitioned from a diet based on fibrous plants to mostly meat-based diets.. But this paper offers evidence that both plant carbohydrates (carbs) and meat were crucial in human evolution. In their words:

We contend that in terms of energy supplied to an increasing large brain, as well as to other glucose-dependent tissues, consumption of increased amounts of starch may have provided a substantial evolutionary advantage to Mid-to-Late Pleistocene omnivorous hominins“.

This photo is missing some starches!

Actual physical remains of early hominins are quite rare, so there is a lot of uncertainty about their lives. As already mentioned, there were several important changes in hominin morphology (size, shape, and structure of an organism) related to the appearance of Homo erectus (teeth, digestive length, brain). Anthropologists propose that they occurred with a change from a “high-volume, low-energy diet” (lots of fibrous plant material that’s not very calorie rich), to a low-volume, high-energy diet (so foods that are more packed with energy like meats and starchy roots & tubers). 

It looks like climate fluctuated between moist and dry periods, which required flexibility in diet (omnivory).. Increased meat consumption has been suggested as an important buffer against such environmental change (and helped expend into new unfamiliar environments), but high starch plant foods might have also been a very common and important part of the diet- especially when cooked. The timing of widespread cooking is not known, but it is argued that it was long enough ago to allow for biological adaptations to take place.

Note: Secure evidence of the use of fire to cook dates to about 400,000 years ago, though some suggestive evidence for a relationship between humans and fire dates to at least 1.6 mln years ago.

The fact that early hominins ate starchy foods is supported by various evidence (the paper goes through rather wordy technical anthropological examples that I fail to summarize in a simpler way). But while meat-eating evidence usually survives (e.g. animal remains with cut marks suggesting being butchered), evidence for plant foods doesn’t, which makes it hard to reconstruct ancestral diets based on physical remains alone (and biases them towards exaggerating meat eating).

Co-evolution of cooking & carb-digesting genes

Humans have the ability to digest starches with the help of enzymes in saliva- salivary amylase! AND humans are quite unusual as we have high levels of these enzymes, suggesting an adaptation to diets rich in cooked carbohydrates. Also, people from populations with high-starch diets have generally more AMY1 copies than those that have traditionally low-starch diets (hey! adaptation!).

Amylase (salivary amylase or AMY1)- enzyme that begins digesting starches in the mouth as it’s present in the saliva. Authors hypothesize that cooking and variation in the salivary amylase gene copy number are correlated.

The variation in copy numbers of salivary amylase genes is an important point of the paper – these enzymes are pretty much ineffective on raw starch, but cooking substantially increases their potential to provide energy/calories. So multiplication of the salivary amylase (AMY1) would become selectively advantageous only when cooking became widespread. (It’s been estimated that the three human AMY1 genes have been evolving separately for less than 1 million years). The authors theorize a gene-culture co-adaptation scenario here: cooking starch-rich plant foods (cultural evolution) coevolved with increased salivary amylase activity in the human lineage (gene evolution). Without cooking, eating starch-rich plant foods probably couldn’t meet the high demands for preformed glucose noted in modern humans.

Note: A mutation that is selectively advantageous means a change in DNA that gives a survival advantage to a particular genotype under certain environmental conditions. SO in an environment where starches are available (e.g. you can find a lot of roots and  tubers) and humans have learned to cook, having more copies of the AMY1 gene that aids in digesting cooked starch would allow those folks to survive more (e.g. in times of food crisis when they can’t hunt or gather other sources of food, etc.) vs. folks who don’t have that mutation.

To further test the paper’s hypothesis, we need “a convergence of information from archeology, genetics, and human physiology”. So let’s stay tuned 🙂


Well, i’m at around 900 words, which is more than the summaries i hope to do in the future! In my defense, this paper was FULL of fantastic information, often rather technical and challenging to explain in less words. I do have some extra content below i found fascinating if you found this summary interesting!

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