Sunday, May 22, 2011

Fast Food, Weight Gain and Insulin Resistance

CarbSane just posted an interesting new study that fits in nicely with what we're discussing here.  It's part of the US Coronary Artery Risk Development in Young Adults (CARDIA) study, which is a long-term observational study that is publishing many interesting findings.  The new study is titled "Fast-food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis" (1).  The results speak for themselves, loud and clear (I've edited some numbers out of the quote for clarity):

By comparison with the average 15-year weight gain in participants with infrequent (less than once a week) fast-food restaurant use at baseline and follow-up, those with frequent (more than twice a week) visits to fast-food restaurants at baseline and follow-up gained an extra 4·5 kg of bodyweight and had a two-fold greater increase in insulin resistance.
Fast-food consumption has strong positive associations with weight gain and insulin resistance, suggesting that fast food increases the risk of obesity and type 2 diabetes.
A 10 lb difference in weight gain over 15 years may not seem like much, but believe me, for this type of study, that's a massive association.  It's a rate of weight gain that would make a lean person overweight in about 30 years.

Fast food, like all industrial convenience food, is professionally designed to maximize reward value and is therefore exceptionally fattening and unhealthy in my opinion.  Most studies of this type measure specific dietary components, like fat, carbohydrate, fiber, meat, dairy, and vegetable intake.  What those studies miss-- which I think is a critical factor-- is the form in which those nutrients/foods are consumed.  This study addressed that by looking directly at the consumption of industrially processed food, and it found a striking outcome.

Lately, I've been collecting data on how the US diet has changed, qualitatively, over the last 200 years or so.  I have some graphs that are very telling.  I'll be gradually releasing them on this blog and in my upcoming talks.  A gentleman named Jeremy Landen, who I'll introduce in more detail later, has been collaborating with me on this.  Here's one of my favorite graphs, as a sneak preview.  It represents spending on food consumed at home (green), food consumed away from home (blue and red), and fast food (red), as a percentage of total food expenditures:

The data come from USDA figures; fast food expenditures were not tracked before 1929.  There are a few things to note here:
  1. 93 percent of food was consumed at home in 1889, and most of that was homemade from scratch.  
  2. In 2009, barely half (51%) of food was consumed at home, the rest was consumed in either full-service or fast food restaurants. Probably a high proportion of what was consumed at home was actually processed food. 
  3. Fast food was not a significant expenditure before 1960, after which it rapidly gained in popularity.  Today, fast food accounts for 18 percent of total food expenditures. 
The obesity epidemic began between 1970 and 1980.  If we're looking for an explanation, fast food is a damn good candidate.  In my opinion, fast food isn't the only factor, it's just an easily measured form of industrially processed convenience food.  The modern US diet consists mostly of food professionally designed to maximize reward value, including fast food, snack food and and even most full-service restaurant food.  We're eating the human equivalent of the rodent "cafeteria diet".  I think that's a major contributor to obesity, diabetes and associated illnesses.


David Pier said...

When I actually imagine myself back in 1900, it is easier to start to accept your hypothesis. It would be hard to get as excited about food back then. Reading the posts previous to this, I was trying to reconcile these ideas with my daily experience, and I wasn't seeing it very strongly. I'm surprised that you didn't mention the conspiring factors of omega 6, sugar, etc. I still and pushing for a flowchart!

allison said...

Fast food is full of fructose and other highly refined carbohydrates and lots of linoleic acid. A Supersized Coke alone contains enough HFCS to turn your liver into foie gras.

Ross said...

Was Earl Butz (Sec. of Ag. 1971-1976) talking about agriculture or our waist lines when he said "get big or get out" in the 70's? Funny how the cheap food industry seemed to really grow in the 70's. The plan worked, but we now know it is killing Americans. Good intentions, bad results. Time for a change.

Unknown said...

I grew up in the 80s/90s in a home where we ate fast food regularly, and what we did make at home was usually something along the lines of Hamburger Helper or boxed mac'n'cheese (served on paper plates because my mom wanted as few dishes as possible). There were a lot of things that I was simply unaware that you could make from scratch. It never crossed my young mind that somebody had to invent the recipe before it could be mass-produced- I thought that whatever you wanted, you just went to the store and got a box of. I'm sure I'm not the only one who grew up that way.

A big part of why we ate so much fast food was convenience (drive through on the way somewhere, not enough time to go home and cook, it's easy to eat in the car). To get rid of fast food, americans would have to see cooking as worth their time, not a burden, and I was raised that cooking is a huge hassle.

It was an amazing epiphany when I realized that things tasted much better and were actually not that much harder to make when I made them from scratch. Now I cook everything myself, except for the occasional restaurant meal with friends.

Unknown said...

This food reward concept is an eye-opening thing to me. No offense to anyone posting above me, but as a first generation american citizen (from an european background) eating in a car is a very foreign practice (obviously if time is lacking then them's the breaks; however making the time would avoid that silly "fast-food" hysteria.)

Anonymous said...

The graph is not telling the whole story. It is showing percent of food spending. Often the meals at fast food and other "away from home" sources are more expensive than something cooked at home.

A more appropriate graph would be percent of calories from each source. It is likely that the home wedge would shrink beyond 33%.

Richard said...

I think the food reward idea is useful, but in this article, when you say processed, what exactly does that mean? As I see it, lots of foods are processed, in one way or another. Making cheese is a process.

I tend to agree that excess processing, such a bleached white wheat flower, is bad, but then I am also opposed to wheat as a food. Search djokovic and wheat, for example...

Meanwhile, how about a correlation with PUFA, and soy in particular, and a side order of HFCS with that wheat? Fast foods are loaded with these things, and even the foods at home if you are not careful.

It just seems to me that "fast" foods are not inherently unhealthy. Potatoes cooked in coconut oil, or animal fats? Boiled potatoes with butter? A hamburger in the form of a Salisbury steak? Real cheese instead of what they use now? Water instead of the super-sized soft drink?

John said...

We should consider that the "other away from home" food quality has undoubtedly decreased. Top restaurants (when shown on Food Network and such) use plenty of soybean oil and sweeteners/sauces that contain HFCS.

Harry said...

Very good series on food reward Stephan...thank you.

Just wondering why Kessler's "The End of Overeating" isn't on your recommended books list? Except for some technicalities about settling points, you're pretty much advocating the same thing as he did (i.e. reward value of hyper-palatable food is driving over-consumption).

Anonymous said...

im a youngin sort of, born in 1985, but every single one of my childhood meals was served and made from scratch at the dinner table with the entire family. i use to get so jealous of kids who got to eat fast food and order in food for dinner. we didnt even have a microwave and i had no concept of a micro-dinner.

my parents were, and still are the biggest tighwads i have ever met in my life but regardless of how a lb of meat was stretched growing up, it was all from scratch. ever school lunches were usually in thermos with leftovers which again, i was jealous of the kids who got cafeteria food

i have never been as thankful for my cheapskate parents and their adamency on our family dinner. i think you lose the food reward with this b/c at meal time, yes your eating but the focus isnt so much on the food, it is on the time with the family at the table. we ate dinner everynight because we werent going to bed hungry. we didnt pack up and go to McDonalds for happy meals with toys which further accentuates the food reward not to mention 99% of the dips and sauces there are sweetened to go with meat which is a concept i have never understood. sweet meat? thats gotta be at the top list of reward foods

Jason said...

How do you explain the societies that had significant rates of obesity that did not have access to fast food?

I think the PIMA indians are a great example.

Stephan Guyenet said...

Hi Dan,

I agree, but it was the best I could do. The USDA doesn't track it by calories as far as I know. The numbers aren't really that important anyway, what matters is the trend.

The proportion of food consumed at home that was eaten as processed food has also increased over time, although unfortunately I don't have any graphs to illustrate that. The overall point is that our diet has shifted heavily toward commercially produced convenience food.

Hi Richard,

That's why I try to say "industrially processed" rather than just "processed". Usually what I mean by that is processing steps that are impossible or impractical in the home, and particularly steps that are not indigenous to long-term healthy cultures. What I mean in this context though, is more than just "refined". I mean foods that have been professionally composed to maximize reward value so that you'll keep buying them. Things like chips, candy, cakes, fast food, etc.

Hi Harry,

I haven't read his book yet, but I plan on it.

Hi Jason,

Fast food is bad because it's industrially processed, composed of unhealthy ingredients and prepared in ways that maximize food reward. The Pima have been eating government "reservation food" for the better part of a century, and it fulfills all of those criteria. Fry bread, other white flour goods, sugar and sweetened foods, canned foods, etc...

chris said...

I think an important part is that fast food is quite palatable, but doesn't require much effort.

Time invested is an important signal the mind uses to gauge how rewarding something is. Spend 40 minutes roasting potatoes yourself, and a small amount is quite enjoyable, even with much less fat.

Easily obtained reward-dense food desensitizes you to it, and instead of greater reward coming from a more difficult culinary technique "How hard did I work for it", the enjoyment is correlated with "How much did I spend and how much volume did I get?"

Bill Strahan said...

I believe you've misinterpreted your data. The graph shows percent of total spending, not percent of consumption.

So stating that 93% of food was eaten at home in 1889 is probably not accurate at all. Eating out has always been more expensive than cooking at home, and I believe the difference was even greater 100 years ago.

So, I'd wager that much more than 93% of food was eaten at home in 1889 if 93% of the spending was on food eaten at home.

Fast food has become relatively cheaper as time has gone by so the disparity by %spend versus %consumption is probably smaller today.

Bill Strahan said...

Oops, hit enter too quickly. Basically, I think the picture is worse than it looks in the progression of eating out or fast food versus home cooking.

That said, I have reached the point I dislike going out to eat. The closest I get to fast food is the occasional trip to Chipotle, and eating out tends towards a nice steakhouse. Even then I find myself thinking I just can't get the same quality food that I can at home.

My wife and I are making progress though. Our kid's friends used to open our refrigerator and say there was nothing to eat. Their eyes are trained to scan for packages. Now they ask us if we'll make something, and they all want to come to our house for food!

Amazing how a little ground beef and sweet potato can seem scrumptious when your palate has been so abused with fast food and macaroni and cheese.

Todd Hargrove said...


This is a great series I am really enjoying it.

Interesting that low carb and low fat are both unpalatable but combining them raises palatability. Its like the combination is greater than the sum of its parts. I can't think of a reason why the body would prefer to have both at the same time, so I suppose this is an example of a supernormal stimulus.

This lends some support to Kwasniewski's idea that low fat and low carb are each OK but you need to avoid the "forbidden zone" in the middle.

I wonder whether you could keep palatability low by not combining cars and fat in the same meal, but using them both in the same day. For example, you could get the benefits of variety and still have a very low palatability diet with a low carb breakfast, low fat lunch, then a low carb dinner, etc. I suppose as a practical matter just eating whole foods is where the real payoff is, but I find this an interesting speculation for someone who really needs to lose weight.

Dogster said...

Are you saying that food that is more rewarding is more fattening? I eat "fat" portions of meat cooked in coconut oil, home made thai sauce and coconut milk. Is it rewarding ? Absolutely yes. Fattening ? Humm - my experience leads to believe its not.
If you are referring to ONLY processed foods which are designed to be more rewarding are fattening, could it be the neolithic agents of disease which cause the fattening regardless of the food reward quality?

taw said...

I have doubts about your "reward" theory. Can we measure this "reward" in any way, even roughly, or is it just some "here magic happens" thing?

If it's just inverse of satiety/calories (and it's not obvious why it should be called "reward"), it's pretty easy to test, as it strongly correlates with macronutrients - proteins are a lot more satiating, and sugar a lot less satiating per calorie than fat and complex carbs. But we don't really see strong effect here - or high protein, high fibre, or high potato diets would be super-effective.

If "reward" has something to do with taste or satisfaction after eating, then fast food being "rewarding" is quite obviously wrong. In any case, we can measure that (how tasty food is vs calorie intake), but I doubt we'll find anything. If this was true, paleo diets would be straight way towards diabesity.

So what is this "reward" really?

Rat experiments are really not that terribly relevant to human diet, so this is some argument, but not a terribly good one.

I still think pollution in industrial food (trans fats, omega 6, hormones, and who knows what else) and inflammation and hormonal dysregulation they cause is a much more obvious hypothesis, and it fits human data perfectly well.

By the way, there's plenty of poor nations with high obesity rates. I doubt they eat out that much, or can afford very "rewarding" food.

From my data gathering it seems all of them migrated towards very high vegetable oil high sugar diet (also usually higher wheat intake, lower potato/rye intake, and other minor changes).

Now this isn't terribly conclusive data, but isn't this a pretty strong argument that industrial vegetable fats and other crap (which they use a lot in poor countries) is a much bigger factor than fast foods (which they cannot really afford)?

David said...

Tell that to Don Gorske, he just ate his 25,000th big mac

Andrew Wallace said...


Seems to be a lot of confusion re the word "reward", and think you might be in a unique position to try to coin a better phrase.
"Rewarding" here doesn't just mean that it "tastes good". As I understand it, when you say "rewarding" you mean unconsciously so - appealing to us in some way deep down in our limbic system, which then gets super-stimulated and throws our metabolism out of whack.
On the other hand, a simple home-cooked meal you worked hard to prepare, made from food you worked hard to grow in your own garden and eaten together with friends or family is also extremely "rewarding". So too, for example, is a small but beautifully-presented plate of sashimi at a nice Japanese restaurant. These two meals both seem to appeal more to our higher senses (cerebrally rewarding?) and I imagine have none of the negative metabolic consequences you are talking about. Indeed, I'd imagine that eating foods which are rewarding aesthetically, socially , ethically, intellectually, spiritually even, may be a big part of the solution.
So… any ideas for another phrase to use instead of "rewarding"? Sorry, no better ideas myself…


psychic24 said...
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psychic24 said...

Can anyone explain how to someone is supposed to reasonably transition to a healthier diet. I understand the outline of how to eat "correctly", but it seems that with every study performed the adherence difficulties suggest somewhat of a problem (i.e. how do you stick with it). My main contention is that regardless of people saying LCD's help you access fat tissue, reducing the need for external calories and thereby reducing hunger, there are still adherence issues in these diets.

gunther gatherer said...

Todd Hargrove, I'm intrigued by the alternating low-fat/low-carb idea. It does seem that combining fat with carbs is what makes them palatable. That and salt, sugar, and other spices that we add now.

You can imagine that in our evolution, without refrigeration there was no way to eat both carbs and fat at the same time. Before storage techniques arose (drying, fermentation, etc.), carbs and fat were seasonal foods that came and went every few months. Except maybe nuts, and milk (human or from herding), which do have both at once...

Anonymous said...

I'd be more curious to know what the average weight gain in all participants, rather than picking on the fast food.

The other problems with studies like this is eating a lot of fast food is a good proxy for not being able to cook ANYTHING for oneself; or just relying, for instance, on microwave meals at home.

Beth@WeightMaven said...
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Beth@WeightMaven said...

You write: "Probably a high proportion of what was consumed at home was actually processed food."

Um, yeah! Does the USDA differentiate spending on fast food consumed there versus consumed at home? I'm guess that a lot of families are doing take out frequently. And what's not takeout (boxed cereals, Wonder bread, frozen pizza) is not much better than fast food.

Either way, I'm completely with you (and David Kessler) that processed, industrial food is wreaking havoc with our appetites.

That said, I also think that what's happening downstream as a result of all of this added sugar/fructose, refined wheat, and veggie oils (e.g., in the liver) is pretty important too.

WilliamS said...

For me, the idea that fast food and other industrially processed food is highly rewarding—and eaten in excess for that reason—is hard to relate to. My girlfriend grew up in Europe. She's always commenting about how the food here in America, particularly the highly processed stuff, doesn't taste nearly as good. As a result she eats more of it because it isn't very satisfying.

When we go out, if the food isn't particularly good, both of us generally want dessert or something else additional, because we *aren't* satisfied. If the meal is great, and we feel highly "rewarded," we eat less and don't crave dessert, etc.

She believes that the French, for example, stay relatively thin precisely because their food is so fantastic and as a result there is little temptation to overeat. Even when they enjoy their superb sweets, a few bites is all it takes to achieve satisfaction and a feeling of satiety. Industrial cake, cookies, ice cream, etc. don't generally taste all that good and so one is tempted to eat and eat in the frustrating quest for satisfaction.

I believe the same thing happens with other pleasures of life. We don't guzzle a great bottle of wine; each sip is highly rewarding and holds us for quite a while. A cheap bottle gets drained fast! I think sex is like this, too: the compulsive need for it arises only when the quality is low and the experience not fully satisfying.

So, I can see the possibility that low-quality industrial food contributes to overeating, but if so because it is generally quite *un*rewarding. At least that's the way it seems to be for us.

Stargazey said...

As I understand it, when you say "rewarding" you mean unconsciously so - appealing to us in some way deep down in our limbic system, which then gets super-stimulated and throws our metabolism out of whack.

That reminded me of something from a few years ago. When I first heard that McDonald's had invented something called the McRib, I told myself whatever a McRib is, it's sure to be incredibly tasty (to an American) and will make people come back for it over and over.

The successful food companies probably have scientists and test groups to help them figure out what combinations of sweet, salty, fatty, crunchy, smooth, colorful and aromatic will appeal to the most customers and will keep them coming back for more. Oddly enough, the winning combinations will probably not be whole, natural foods.

Jo said...

Stargazy's last paragraph about foods being designed to appeal is elaborated in "The End to Overeating". The book made a lot of sense to me and reminded me of conversations with my mother as a kid. When I complained of being hungry (but was really just bored) she'd offer me and apple. I'd reply that I was only hungry for chips/pie etc, but she'd hold her ground and insist that if I was really hungry that apple would be incredibly appealing. I can eat eat products that are industrially designed way past the point of being full. But meat, veggies and fruit I cannot be bothered and stop when satisfied.

Stephan Guyenet said...

Hi All,

It's occurring to me that I didn't do a good job of clearly defining the phrase "food reward". It's a psychology term with a specific meaning and it's not the same as liking something, although reward and liking often come together.

Food reward is the process that leads to the establishment and maintenance of behaviors favoring the acquisition of a particular food. In other words, some foods are "reinforcing" or "habit forming", sort of like a pleasure drug, although not necessarily to the point of addiction (reward behaviors are totally healthy and normal, up to a point). This process has been clearly demonstrated in rodents, humans and a variety of other animals.

We are wired to learn by trial and error what foods are good for our survival in the natural environment. Our brains guide us toward these foods that it has determined are "good" by making us gravitate toward certain flavors, textures, locations and other cues that we've learned to associate with rewarding foods. We want rewarding food, but we don't necessarily enjoy it once we eat it. There's a difference between "wanting" and "liking".

Medjoub said...

Andrew rightly says:

"Seems to be a lot of confusion re the word 'reward'...'Rewarding' here doesn't just mean that it 'tastes good'."

While some of the concepts here do seem to need clarification (at least to laypeople like myself), according to Stephan's series the term is one that is used in the psychological literature to describe a certain mechanism or set of mechanisms. Thus, changing the terminology for the sake of clarity here is probably not favorable. Anyway the apparent lack of clarity PROBABLY just indicates that we don't really understand what is being described.

It's always appalling to me when non-experts assume that their contentions are as equally well-conceived as the concepts they'd like to "refute." This is, of course, untrue and arrogant. Andrew's post above makes the salient point that the reward concept actually points toward some deeper metabolic function, and I'd reiterate (what Stephan says) that it is an important part of a system, not the only factor. Anecdotal, ill-conceived refutations are only clouding up the matter. The essential point, in my mind, is to fully understand what all of this means before we launch our critiques.

karl said...

Is the fast food weight gain in part due to Leptin resistance? Which comes first - insulin resistance or leptin resistance?

Fast foods are high in fructose containing sugars as well as carbs. (selling carbohydrate foods is quite profitable compared to meat products).

The carbs and fructose both increase triglycerides -- which is thought to cause leptin resistance.

< Warning: below two words are quit similar Leptin and lectin - they are not the same thing >

Looks like lectin might also cause leptin resistance
Agrarian diet and diseases of affluence – Do evolutionary novel dietary lectins cause leptin resistance?

According to one source, Lectin seems to be derived from particular foods:

* Grains, especially wheat and wheat germ but also quinoa, rice, buckwheat, oats, rye, barley, millet and corn.
* Legumes (all dried beans, including soy and peanuts),
* Dairy (perhaps more so when cows are feed grains instead of grass, a speculation based on research showing transference of lectins into breast milk and dairy??
* Nightshade (includes potato, tomato, eggplant and pepper).

Leptin is activated by amylin which is secreted at the same time with insulin. Leptin seems to be closely related to IL-6 - involved with inflammation and disease. According to wikipedia IL-6 is "relevant to many disease processes such as diabetes, atherosclerosis, depression, Alzheimer's Disease, systemic lupus erythematosus, prostate cancer, and rheumatoid arthritis." Studies are showing that elevated leptin is also causing disease - are the IL-6 receptors sensitive to leptin?

So is dietary lectin one of the reasons why paleo diets work? ( The gluten in wheat seems to provide a lot of lectin).

I don't think we understand all of what regulates leptin resistance. Is it more or less important than insulin in regulating the amount of adipose tissue?

How important is dietary Lectin? What is the the role of the co-secretion of amylin with insulin?

As usual - more questions than answers.

JBG said...
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Beth@WeightMaven said...

I gotta give Matt Stone props, as the 6-part video series at does a fabulous job of explaining how our evolutionary reward systems are maladapted to the "super normal stimulation" we're exposed to.

YBOP primarily looks at dopamine, so I think Gabor Mate's Brain Development & Addiction is a nice complement for two reasons: 1) if dopamine is wanting something, then opiates are the liking. Between wheat and sugar, it seems very plausible that we find modern industrial food rewarding! (Mate also looks at the implications of development on stress and impulse control in the brain.)

The other interesting concept in the Mate video is the implication that early development (or lack thereof) is what predisposes people to potential addiction. If so, it might explain why someone can eat 25K Big Macs without a problem and another person can't.

And Mate doesn't even touch on the interesting work being done on pre and postnatal epigenetics.

Caira said...

I'm wondering how much of a factor something as simple as forks and spoons might be.

When I serve tacos at home, the goodness is all dripping out the other end, which makes me and my family eat faster than we might otherwise. It takes a couple of minutes for the fullness sensation to register in our brains, at which point we have already overeaten.

Most fast food would be the same way: food designed to be eaten with our hands. I would guess that we're less likely to pause between bites when our hands are covered with grease and sauce. "Fast food" is prepared quickly, served quickly, and eaten quickly.

I also wanted to say that I agree with the sentiments that much of the food that is eaten at home is of poor quality. Soda shows up in large quantities at fast food, restaurants, and home.

"Usually what I mean by that is processing steps that are impossible or impractical in the home, and particularly steps that are not indigenous to long-term healthy cultures."

I agree with this definition, and it has been my guideline for some years. I might buy plain yogurt, or spaghetti sauce (without soybean oil or HFCS), because while those are things I /could/ make at home, I might not always have the time to.

JBG said...

I posted the note below but deleted it when I discovered that several comments, including Stephan's, had been posted past the last one I had read.

I've decided to re-post it because I believe we need terms that allow us to distinguish between healthy (non-deceptive) reward and the engineered phony reward provided by industrially-processed foods.

Both are "reward" in the technical sense, but the distinction is crucial.

= = = = =
In line with other commenters here, I have felt for a while that "rewarding" is not the right term. "Addictive" is perhaps too strong, but it's in the right direction. "Deceptive" is closer but doesn't feel like it covers the whole concept.

The point about industrially-processed foods is that they have been phonied up to *fool* our perceptive apparatus. "Bait and switch" is a pretty exact appellation, but awkward to put into adjectival form.

As several others have well argued, it seems better to reserve "reward" to describe foods/experiences that are in fact satisfying. The point about industrially-processed foods is precisely that they are UNsatisfying, but in a way that keeps us eating.
= = = = =

If we leave "reward" in its technical sense, then we also need an informal term for healthy reward.

Reid said...
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Helen said...
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Helen said...


That's an interesting observation about utensils slowing down consumption. It goes along with the idea that mushy or crunchy (like chips and crackers) food is more associated with overeating (somewhere in a past post by Stephan). I've known Westerners who eat with chopsticks to slow themselves down, though someone used to using them is probably not slowed down.

I think others have commented on this, but Americans being so busy with work and their kids' ridiculous amounts of structured extracurricular activities, and the absurd amounts of time they spend in their cars factor into this.

In school and at work we are given about 30 minutes to eat our lunch. I found it hard to eat a salad or hearty stir-fry in that amount of time, but it was easy to scarf down a microwaved burrito. Also, much easier to eat such a thing in the car.

Dunkin Donuts totally promotes the eat-in-the-car-on-the-run-at-your-desk mentality in their ad campaigns. But how much time are you sitting inhaling exhaust waiting to buy some crap at their drive-through window? Couldn't you have brought some soup from home? It doesn't really make sense, but people fall into the trap.

Let's not forget that it often feels more like a "treat" to get something to go than something you had to dutifully make yourself. And working an average of 46 hours a week with two weeks vacation (12 more weeks in total hours than Europeans), I can see why Americans feel they need a treat.

A friend of mine signing her kid up for little league asked another mother how they fit dinner in with three days of practice after school. The answer: "It's called Hot Pockets."

Jim said...

Stephan, I'd like to put in another vote for you to address Todd's conjecture that the combination of glucose and fat is particularly problematic (wrt fat gain).

I've suspected this for years, and do well alternating low-fat and low-carb meals (I primarily have the low fat meals after workouts).

Forgive my simplistic biochemistry (that's part of why I'd like you to address this question), but here's the gist:

If you consider a low-fat, high-carb meal (starchy, not sugary -- perhpas sweet potato, without added fat, and some lean meat), the glucose will fuel immediate metabolic needs, and replenish glycogen before anything else. It will raise insulin and leptin. And it might be that little to no fat is stored after such a meal.

If you eat fat with this meal, most of the fat will be put into the fat cells relatively quickly, since it's not needed for immediate metabolic needs. So, with a similar leptin and insulin response in each case, we have fat stored in one case, and not in another. Long term, some of the fat would come back out, but perhaps not all of it.

High fat, low carb, on the other hand does not trigger much insulin. So not much fat is stored in that case either. Leptin doesn't rise much either, but substantial satiety still results (at least so I've heard).

If the conjecture is correct, and Robert Lustig is correct about fructose being turned to fat very readily, then that means sucrose might be roughly functionally equivalent to a nice little bundle of glucose + fat, making it lipogenic all on its own.

This seems to be consistent with what you're saying. You could frame this conjecture as a hypothesis about which foods are most apt to be "rewarding" (fat + glucose in the same meal).

It could be that there's an additional flavor-based CNS conditioning effect that makes us addicted to sugar and carb/fat combos, and that the consistency of flavor allows us to get triggered more quickly. This could be part of why we might expect home-cooked whole foods to be less rewarding -- because the flavor consistency is not there.

So it's the super-consistently-flavored fat/carb combos that are most "rewarding".

Adam Haritan said...

Great article, Stephan ... very practical advice, and yet, not surprising.

I notice that some people who advocate eating wholesome animal products don't necessarily dissuade followers from partaking in fast food. I suppose their rationale is to get the essential nutrients in ... no matter what.

Is it better to obtain animal nutrition at any cost rather than neglecting it? What is your take on this?

I am of the firm belief that all fast food should be avoided. Even innocuous items like salads and healthy wraps are replete with artificial ingredients and added sugars (and hardly any of it is organic). Don't forget the energy cost, the abuse from CAFOs, and the injected greed in every bite.

Fast food = fast death.

Anonymous said...

According to the data, obesity was nearly flat in the 1970s, and the "obesity epidemic" didn't start until after NHANES II in 1976-1980. (Graph here.)

Given that the quickest growth in fast food consumption was approximately from 1960-1978, I'm not sure that blaming obesity solely on the palatability of fast food quite fits the data. The government's decision to back the lipid hypothesis with official nutritional recommendations in 1977 seems to be more closely correlated, as is sweetener consumption (graph).

Furthermore, I find the definition of "food reward" to be somewhat circular, even in the psychological sense. Yes, rewarding food is that which elicits a reward response, but that's just a tautology. We still must explain what makes food rewarding but not satiating, or all we've done is restate the problem in a way that makes us sound smart.

I hope to see Stephan address these issues. Meanwhile, this article may be of interest: The Grand Unified Theory Of Snack Appeal.


Stephan Guyenet said...

Hi Jim,

When you're talking about fat mass changes, it's useful to think about it in terms of calories going in and calories going out. However insulin, leptin etc are causing the nutrients to be handled, the same proportion will end up in fat mass either way unless energy leaving the body is increased. The form in which calories are ingested (i.e., fat vs. carb) doesn't seem to have much impact on energy expenditure, although protein does increase it modestly.

Hi J. Stanton,

The obesity epidemic began in the 1970s in children, and spread to adults in the late 70s to early 80s. See this post:

Also, keep in mind that there's a certain latency period during which people are gaining weight, before they will be classified as overweight or obese.

Anonymous said...

Is the metabolic damage that can be caused by the reward value of engineered food independent of nutritional issues like NADs / malnourishment etc?

Could much of this be explained by the gap between what our body expects will be good for it (ie psychologically rewarding / desirable) and what really is good for it (ie nutritionally rewarding / nourishing). Foods could be either:

1. Both desirable and nourishing (a meal at a good French restaurant)
2. Desirable but not nourishing (a piece of cake)
3. Less desirable but nourishing (unseasoned meat and veg)
4. Neither desirable nor nourishing (cardboard)

Numbers 1 and 2 are both engineered to be desirable, but number 1 satisfies more of our nutritional needs, while number 2 leaves our body still needing more, so the desire for more reward doesn't go away.

... or is what you've been talking about something else altogether? If so, this seems quite a paradigm shift. Have we been putting too much emphasis on nutrients and toxins so far?

One final question: How much of a role do you think food reward has had on the nutritional transition as a whole, and not just obesity? Does it have a role in the other diseases of civilization? Or is this just a problem of the obese?

Megan said...

As I was born jut before the end of WW2 I grew up without sweets and most fruits.

My only experience of fast foods as a child was the occasional fish and chips from a newspaper, sitting on a sea-front in Scotland. My first experience of eating out was when I was 18,when I got luncheon vouchers from work.

I always ate well, and although I was "a bonny lass" I was never fat - not until I had my first child, and couldn't get rid of a few excess pounds.

This coincided with the "low-fat" revolution, and as I had no concept of low-fat cookery I was grateful for the ready-prepared diet foods that quickly appeared in the supermarkets.

That started a yo-yo period where I ended up six stone heavier than when I started, and all the time I followed the "expert advice".

I only began to get my weight under contro when I discovered low-carb and stopped using food prepared for me by an multi-billion pound industry.

Now we only eat restaurant food on high days and holidays and we're healthier for it, although we cannot rid ourselves of all the damage of the last 40 years.

majkinetor said...

2 karl

Nuts are part of the paleo diet and are rich in lectins.

Since lectins are ubiquitous in nature, I doubt they play substantial role in 'paleo state of health'.

Also, it looks like epithelial cells must be damaged in order for lectins to be toxic. Since they live in harsh environment, the probability of damage is big, but with absence of industrialized foods this damage should be minimal.

CarbSane said...

@Megan: You raise a good point. I think "dieting" in general tends to steer one towards processed foods because it takes the guesswork out of counting calories. Eating foods w/o a label requires weighing and measuring. Cooking "dishes" requires calculating amounts. Easier to get sauce from a jar than to make your own and figure out what's in there. Easier to fix a Lean Cuisine than it is even to measure out that exact amount of pasta and sauce. This is why programs like Nutrisystem and Jenny are popular and I believe will remain so.

Anonymous said...

@J. Stanton; the factor, which nobody wants to talk about, is women working.

Women working means kids are being fed fast food, which then turns into fast food for the entire family. You've got better options than 30 years ago -- plenty of carry-out vs. going to McDonalds -- but it still hurts.

Big factor in Japan and Korea staying thin. Women there still cook.

Morris said...

I find your discussions objective, interesting and stimulating. However that said, your theory ie carbs in = carbs out, must apply in a general case to be valid. I do not know that there is a general case, perhaps we are all special cases. I am an example. I was normal weight (BMI=23, lean) prior to experimenting with LC nutrition and have remained at about the same weight 10 months later. I have kept accurate records over the last 28 weeks during which energy intake varied from 2400->3300->2200Kcal and is now at the low end. My (visible) fat mass did not change. The low energy (ie below 2500) is only 4 weeks old. I lost about 2-3 # during this 4 week period. The loss appears to be internal inventory of feces and water. I have not had or now have any clinical GI tract symptoms so assume my metabolism reasonably well. On the LC regime the food continues to taste great, I don’t have cravings and I only miss sourdough bread, pasta and beer. If you grant that my observations are correct, how can my experience be explained? My speculation is that a healthy metabolism is relatively insensitive to energy input at least in the short term viz. young healthy people seem to be able to do this and if so maybe I am not that special a case. Off topic but the idea that the conservation of energy applies to living organisms is just hilarious, obviously proponents have forgotten their basic thermodynamics.

Geoff said...

@sowhatsitallaboutthen I think that Stephen is talking about a paradigm shift. It's about an upregulation of the adipostat in the brain. Keep in mind his previous post about rats fed ensure, and how chocolate ensure is fattening in rats but vanilla is not.

@all Most of our nutritional requirements are just calories. Energy in the most basic sense. Our body is very good at converting fat to ketones as necessary or carbs to fat as necessary, or protein to carbs as necessary, but we still need enough energy to keep the machine running day in and day out.

There is some basal level of micronutrition that we need, which is why "humans with limited access to animal products have often gone to great lengths to include at least some animal products in their diet" as stated by Chris Masterjohn here: Still, food being "rewarding but not satiating" is not a good explanation. It's old paradigm thinking.

I think the same can be said for this conjecture about mixing fat and carbs and the confounding variables of neolithic agents of disease. Stephen isn't saying that NAD aren't a factor, he's saying that there is a food reward effect independent of them.

I suspect that fast food may create the perfect storm of both highly rewarding food and NAD, which is why it has such a dramatic effect. Still, all of this speculation about forks vs finger food and eating with your family vs in your car shouldn't matter if you buy into the concept of a fat mass setpoint or an adipostat. Any excess calories that you eat as a result of a lag in signalling between your stomach and brain should be relatively insignificant and your brain should be able to easily make up the difference either out of future meals or by temporarily upregulating activity/body temp/etc.

Helen said...


I think there's something to that, but I'd be careful of solutions that include discouraging women from working!

How about two ideas:

1) Everyone works less.
2) Everyone learns to cook.

Married men have much better health outcomes than single men, which does not hold true for married vs. single women. I have a feeling this is because many men are not schooled in, motivated for, and comfortable with cooking. Left to their own devices, they turn to frozen pizza and ramen noodles.

Yes, I'm generalizing, but in general, it's true. I know these paleo and ancestral diet guys all cook. I hope they can make it fashionable.

And let's not forget my first idea. Of course, a lot of things would need to change to make that possible for most people.

There are also strategies for cooking in bulk, once a week or once a month, or in groups. That can make the working-and-cooking trick possible. I can't say I've mastered this, but some have.

Also, watching TV less might free up some time.

karl said...

Hello majkinetor

After I wrote that I read some more about lectin - (one Google search sent me back here to Stephan's blog).
Lectins are a group - and some types seem much worse than others. What is in nuts seem less suspect than wheat - but I think it will take much more research before we know the magnitude of lectin's effects.

In the mean time, I'm still puzzled by what I observe in myself as an appetite stimulating effect of carbohydrates. I once did a glucose tolerance test on my self - the glucoloa has just glucose - no fructose - no lectins and 4-6 hours later I was extremely hungry having temporarily exited my low carb diet.

My personal self observation is that it may not be the carbs that make me gain weight - but the hunger they induce. The years I was on a low fat diet - I was miserable - always hungry - going to bed hungry - as it was easier to resist in my sleep. On a low carb diet, I have appropriate hunger and little trouble maintaining my now normal weight.

Anonymous said...

@Helen; as a single guy, who cooks a lot, that is fine. But the factor I'm talking about is cooking for kids.

Kids who grow up without seeing their moms cook are going both lack knowledge, confidence, and the taste discrimination.

Even more of a problem. I've noticed pregnant women usually crave childhood food. So a kid raised on McDonalds, once she gets pregnant, is going to crave even more McDonalds. And we know where that leads...

Almost every datapoint I've seen suggests women who stay home results in smarter, healthier children. The difficult is almost nobody can afford that luxury anymore.

Mavis said...

Hi Charlie,

I hear that you're talking about kids. We can't afford it, but I have in fact stayed at home the last three years with my twins. (I couldn't really afford to work, either - with childcare costs it was a wash.) But my working friends manage to feed their kids a healthy diet.

But yeah, I have seen some studies with the same findings. (I can't remember if they were adjusted for income or wealth, which would be informative.)

I'm just saying that we're in a new era and we'll need to find some solutions that take into account women working. One solution would be for both parents to work less, and both to cook more.

Interestingly, my mom was a single, working mom and somehow fed us (using a lot of frozen vegetables, meat, and potatoes), and we weren't fat. That was the seventies and early eighties. Microwavable lasagna and mac and cheese weren't yet the norm.

The underlying problem, not usually addressed in the write-ups of these studies, is that Americans are overworked and wages have gone down to the point where you need both parents to work to make ends meet. It would be great if either or both parents had the option of working less (like 30 hour weeks) and could do more cooking and play outdoors with their kids. Both economics and people's personal priorities would have to change.

Peter said...

Charlie and Helen,
I agree with you both. There was a significant societal shift in the 1970's toward working mothers and away from traditional family mealtimes. Time studies show that men on average have not materially increased their help with food preparation and so convenience food was the logical way to make it all work. Another factor is that kids now need to be self-actualized by being in all sorts of after school activities, also preventing a traditional evening family meal. Finally, Stephan's observation that the obesity epidemic started in children makes sense in this context - children in the 1970's were the first to have their tastes altered from a young age by industrial foods.

feelgoodagain said...

Yep totally agree with all of this....refined carbs damage every cell in the body

Heather Twist said...

What do you think about the contribution of iron to diabetes? One of the things that has changed in the US diet is that it is very high in iron, and ferritin levels in the US are quite high. Infant formula has way more iron than breast milk, and our cuisine (esp. fast food) conspires to make the iron added to most starches to be more absorbable. Anyway, ferritin levels track with Type 2 diabetes, and it is known that lowering ferritin levels decreases insulin resistance. It seems that iron stimulates insulin production, because insulin helps sequester the iron, which is rather toxic even though we need it.

Anyway, most of the diets across the world that are associated with less diabetes, are low-iron diets. Even the Maasai actually have low blood iron ... milk blocks iron absorption. The Asian diet has little "red meat" and their rice isn't iron-fortified as it is in the US. I think maybe wheat, making the gut porous, also makes iron over-absorbed.