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Does fast food really make us fat?
Matsa and Anderson next looked at data on individual eating habits from a survey conducted between 1994 and 1996. When eating out, people reported consuming about 35 percent more calories on average than when they ate at home. But importantly, respondents reduced their caloric intake at home on days they ate out (that's not to say that people were watching their weight, since respondents who reported consuming more at home also tended to eat more when going out). Overall, eating out increased daily caloric intake by only 24 calories.
The researchers also find that greater access to fast food restaurants, as created by new highway construction, doesn't much matter for weight. Here is more, including a link to the original paper.
Posted by Tyler Cowen on June 3, 2008 at 09:21 AM in Food and Drink | Permalink
Comments
Interesting.
But note that 24 kcal per day is 8,760 per year. It takes 3,500 kcal to add a pound of fat.
So on this basis, eating out will cause you to gain 2.5 pounds per year.
Posted by: TheophileEscargot at Jun 3, 2008 9:39:29 AM
I find that fast food places are about the only restaurants where you can get a small enough portion for such people as senior weight losers. They are also the only restaurants where you can order a kid sized meal without being refused because you are visibly not a kid, even though you have the caloric requirements of one now. Fast food makes you fat? In fact, it helped me come off an 11-day road trip with a weight gain of only 0.8#, and that includes two calorie-rich Oregon Coast desserts that were NOT in fast food places.
Posted by: Pat Mathews at Jun 3, 2008 9:47:37 AM
Also, according to this Americans are 25 pounds heavier than they were in 1960.
So, if you consider this 2.5 pounds per year over many years, it seems plausible that increased fast food eating could be a major factor behind this change. It could even account for all of it.
So on the basis of the study it could indeed be fast food making people fat.
Posted by: TheophileEscargot at Jun 3, 2008 9:59:29 AM
"So on this basis, eating out will cause you to gain 2.5 pounds per year."
If you assume that what a person would have eaten at home would be exactly what would maintain their weight, and that they choose to eat out everyday, and that a person's choice to eat out everyday wouldn't effect their choice of what to eat, then eating out would cause you to gain 2.5 pounds per year.
Do people factor in the fact that they will be eating out some of the time when they decide what to eat at home?
Posted by: josh at Jun 3, 2008 10:12:35 AM
It would only seem plausible to someone willing to assume that the average American ate out every day of the year. In other words, not plausible at all.
Posted by: Joshua Macy at Jun 3, 2008 10:21:08 AM
Oh, there are all kinds of incredibly complicated factors involved.
But the data presented doesn't really seem to justify the title of the article "Fast Food Doesn't Make You Fat".
The increase in obesity has been 25 pounds in 40 years, or about 0.6 pounds per year.
The figures they give seem to show that fast food could increase obesity by 2.5 pounds per year.
Sure, maybe that's entirely wiped out by opposite factors. In fact, my personal suspicion is that it's largely soft drinks and decreased exercise; not fast food as such; that's to blame.
But the numbers they give don't seem to justify their conclusion.
Posted by: TheophileEscargot at Jun 3, 2008 10:25:22 AM
I've read recently that exercise rates have gone -up-. I'm sure, Theophile, that it is largely due to increased carbohydrate consumption, e.g. soft drinks.
Posted by: Sameer Parekh at Jun 3, 2008 10:35:52 AM
I have not gone through this paper yet but I remember that Cutler et al. (2003) in the Journal of Economic Perspectives made an interesting point: individuals with self constrol problems are those most likely to be affected if the time delay before consumption is reduced (which is what happens when fast food is readily available). These are the ones who will likely spend more than is optimal on food and incur a welfare loss if the health costs of additional weight due to overconsumption are greater than the welfare gain from lower costs of time food preparation. Those 24 calories may well be an average, with most excess consumption concentrated among time-inconsistent individuals, whose BMI distributions is probably shifted to the right (i.e. more likely to be obese than their time-consistent counterparts).
Posted by: Olivia at Jun 3, 2008 11:18:42 AM
I have not gone through this paper yet but I remember that Cutler et al. (2003) in the Journal of Economic Perspectives made an interesting point: individuals with self constrol problems are those most likely to be affected if the time delay before consumption is reduced (which is what happens when fast food is readily available). These are the ones who will likely spend more than is optimal on food and incur a welfare loss if the health costs of additional weight due to overconsumption are greater than the welfare gain from lower costs of time food preparation. Those 24 calories may well be an average, with most excess consumption concentrated among time-inconsistent individuals, whose BMI distributions is probably shifted to the right (i.e. more likely to be obese than their time-consistent counterparts).
Posted by: Olivia at Jun 3, 2008 11:20:09 AM
Olivia, speaking as an overweight individual, the "time delay before consumption" thing seems exactly right to me -- but I'd argue it really doesn't have a lot to do with places like McDonald's.
McDonald's isn't remotely dangerous to my diet. If I want food on the spur of the moment, I'm not going to get in my car and drive a couple of miles to get a lousy burger. I'm going to walk to the kitchen and raid leftovers from the fridge, or pour myself a little bowl of cereal, or stick a BBQ pork bun in the microwave. If I'm out of the house, I'm going to look for a candy bar, or an ice cream cone, both quicker and tastier than McD's.
If I'm going out to eat, almost any restaurant meal around which is not a diet meal is going to have more calories than a burger, fries, and small pop.
Posted by: Sol at Jun 3, 2008 11:56:10 AM
The cooperating states providing the data were: Arkansas, Colorado, Iowa, Kansas, Maine, Missouri, North Dakota, Nebraska, Oklahoma, Utah, and Vermont. Arkansas seems to be the only one in the top ten ranking of state obesity rates. Don't know whether that could affect the conclusions.
Posted by: Bill Harshaw at Jun 3, 2008 1:27:10 PM
I agree with you, Sol, eating fast is not something that we can only do when we eat out or at the McDonald's. The time cost of preparing the food items you mention tends to zero and we consume them at home.
As for the physical exercise story: I am not sure that US obesity rates are so high because of sedentary habits. Actually, people spend more minutes per day doing sports in the US than we do in most European countries. I believe that differences in obesity prevalence are more likely to be explained by differences in calorie intake than in calorie expenditure. Then obesity in Europe is also on the rise so we may be having some convergence there too...
Posted by: Olivia at Jun 3, 2008 2:13:42 PM
Other studies have shown that people are really bad at estimating how many calories they've eaten. I think I'll stick with Seth Robert's theories about what makes food fattening.
Posted by: David at Jun 3, 2008 3:29:40 PM
(1) While people probably spend more time formally exercising now than they used to, I would wager that the level of informal exercise people do (housekeeping, manual labor, walking around, etc.) has diminished considerably in the last few decades due to technological advancements, TV, computers, increased use of cars to get around, a shift towards white collar jobs, etc. So while people may be going to the gym more, it doesn't mean they're still burning as many calories.
(2) Also, wouldn't high carb drinks such as sodas, sweet tea, milkshakes, juices, etc. be included in any study of fast food? After all, it is a part of most value meals.
(3) "It would only seem plausible to someone willing to assume that the average American ate out every day of the year. In other words, not plausible at all."
Probably only a few people eat out once every single day, but I think the average times a year that an American eats out is higher than expected. After all, consider when people are on vacation -- many probably "eat out" for the entire trip, all 3 meals a day. That could make up for weeks of not eating out.
(4) I agree with the poster above - the blame (if any is to be had) is not just on FAST food restuarants, but on all food restaurants, which present even more high-calorie options than fast food restaurants do (Applebees, TGIFridays, Olive Garden, Red Lobster, Outback etc.)
Posted by: 12345 at Jun 3, 2008 5:05:26 PM
(1) While people probably spend more time formally exercising now than they used to, I would wager that the level of informal exercise people do (housekeeping, manual labor, walking around, etc.) has diminished considerably in the last few decades due to technological advancements, TV, computers, increased use of cars to get around, a shift towards white collar jobs, etc. So while people may be going to the gym more, it doesn't mean they're still burning as many calories.
(2) Also, wouldn't high carb drinks such as sodas, sweet tea, milkshakes, juices, etc. be included in any study of fast food? After all, it is a part of most value meals.
(3) "It would only seem plausible to someone willing to assume that the average American ate out every day of the year. In other words, not plausible at all."
Probably only a few people eat out once every single day, but I think the average times a year that an American eats out is higher than expected. After all, consider when people are on vacation -- many probably "eat out" for the entire trip, all 3 meals a day. That could make up for weeks of not eating out.
(4) I agree with the poster above - the blame (if any is to be had) is not just on FAST food restuarants, but on all food restaurants, which present even more high-calorie options than fast food restaurants do (Applebees, TGIFridays, Olive Garden, Red Lobster, Outback etc.)
Posted by: 12345 at Jun 3, 2008 5:06:36 PM
Allow me to be the solo heretic here:
Weight as a function of "Calories In, Calories Out" (supposedly obeying the laws of thermodynamics) is likely dead wrong. Gary Taubes has demolished that, now dangerously arcane in my eyes, meme a while back. Funny how we have all been fooled for so long.
Video explanation here: http://weightoftheevidence.blogspot.com/2008/02/gary-taubes.html
Fast forward to 31:10
Posted by: Varangy at Jun 3, 2008 5:07:32 PM
Still, the US is by far the fattest nation in the world, much fatter than Great Britain (the second fattest nation in the world).
Something environmental must cause that, since the Germans who have the same germanic genes are much thinner and fitter.
Explanation anyone?
Posted by: Gannon at Jun 3, 2008 5:57:50 PM
Theophile, 24 calories per day likely will not have any effect whatsoever on weight. Metabolism expands or contracts to accommodate increased/decreased caloric consumption. You really have to get over a certain threshold before any weight change results. Both anecdotal and scientific evidence supports this.
In one study where participants attempted to gain 25% body weight, some had to eat 7500+ calories per day to accomplish this, meaning their weight stopped increasing before hitting a 25% gain even while they were consuming 7000 calories/day.
Posted by: Cliff at Jun 3, 2008 6:15:33 PM
Weight gain isn't simply a matter of eating more calories. Two people of identical size and physical activity could eat the same number of calories and one could lose weight while the other gains weight.
Posted by: Andy at Jun 3, 2008 6:16:51 PM
Quick somewhat-irrelevant correction to Gannon: the US is the ninth fattest nation in the world.
http://www.forbes.com/2007/02/07/worlds-fattest-countries-forbeslife-cx_ls_0208worldfat.html
Posted by: Michael Keenan at Jun 3, 2008 7:03:51 PM
Thanks Michael Keenan. But I meant real countries, not small islands in the pacific with a few thousands inhabitants. The only real country that seems fatter is Kuwait: and even Kuwait is extremely small. Also, classifying people with a BMI between 25-29 as fat is stupid. Real fatness and significant health problems appear only on people with BMI's over 30.
Posted by: Gannon at Jun 3, 2008 7:50:09 PM
"I am not sure that US obesity rates are so high because of sedentary habits. Actually, people spend more minutes per day doing sports in the US than we do in most European countries."
I believe in most European countries that the people walk more on average. Public transit certainly adds a lot of exercise to the typical day over driving. Also walking to and from local grocery stores etc. instead of driving adds exercise as well. When I was a kid I didn't spend all that much time formally playing sports, however I did spend most of my time in some form of exercise or sport activity. If I was asked if I exercised, I'd say "I never exercise" because I considered it playing.
Posted by: JordanT at Jun 4, 2008 12:49:42 AM
I went to Varangy's suggested video. Huh? Some dude challenges my “faith in the laws of thermodynamics”? And I'm supposed to then believe he can explain a complex biochemical process?
I get the bit about defining obesity as eating too much being circular. That's a linguistic problem, not a chemical problem. He seems to conflate the judgment/definition of obesity with the biochemical process by which fat is accumulated.
Anyone have anything more meaty on Taubes's meme-smashing hypothesis? Lacking that, I'll stick with the well-tested hypothesis that USA (or anywhere) is fat because caloric intake exceeds caloric demands.
People may be weak at estimating their intake, and ceteris paribus, those 24 daily calories make 2.5 pounds in a year. But everyone knows when their pants get too tight. And everyone knows that if they eat less, ceteris paribus, their pants will get looser.
Ultimately, USA is fat because we're O.K. with being fat. It's a choice. And a judgment that fatter is--or is not--acceptable.
Posted by: foxmarks at Jun 4, 2008 12:53:09 AM
Foxmarks, your theory is thoroughly disproven. Eating an extra 24 calories per day will make no difference whatsoever. According to your theory, eating 24 calories less each day would lead to weight loss of 2.5 lbs/year forever. Obviously this is false. What is remarkable is the ability for people to maintain the exact same weight in spite of dramatic changes in caloric intake. "Everyone knows if they eat less... their pants will get looser" is 100% false. There are many people who reduce their caloric intake and do not lose weight. Obviously you are unfamiliar with the science in this area.
Regarding Taubes, unfortunately he is not a genius and he says some stupid things. But he is certainly right that deltaE=Energyin-Energyout is not the whole story. You have to define the system and you have to figure out what causes Ein and Eout. Clearly Eout will depend on activity, but also on metabolic rate, metabolic/cellular efficiency, and digestive efficiency.
If energy is not being efficiently removed from the food you eat and stored in your body and is being excreted along with waste, that clearly contributes to Eout but is difficult to measure. Insulin, as any doctor will tell you, plays a role in how much energy is stored and how much is excreted. Whether his hypothesis that more insulin leads to more storage and less excretion is true I can't say, but it does not seem wildly implausible.
So obviously calories in and calories burned in activity are a significant part of the story. But there are other factors at play as well. Eating less will reduce Ein but also Eout- by increasing efficiency. Therefore small changes in Ein generally have no effect. Taubes' hypothesis is that the amount of carbs we eat, and therefore the amount of insulin released, affects how much energy is stored in fat versus excreted. Not that radical in my opinion.
Posted by: Cliff at Jun 4, 2008 7:47:28 AM
@foxmarks
There is no violation of the first law of thermodynamics.
Their thinking is that energy in (what you eat) and energy out (what you use) are the independent variables with delta E being the simple difference between the two.Taubes contends, with an enormous amount of reference material, that the composition of your diet actually drives the delta E, then your body does what it needs to do in order to either "force" you to eat more (by triggering hunger pangs for example) or by changing your base metabolism or activity levels. The laws of thermodynamics still apply. It's just that your body changes its requirements dynamically. In this model, obesity is not a failure of willpower or laziness (gluttony and sloth), but rather a biological imperative. It treats the body and metabolism as not just a calorie counter, but as a metabolically active organism. This perspective is more consistent with the results of multitudes of studies than the inert metabolically static model.
If it is not clear, what Taubes is saying that the causality is reversed and CalIn - CalOut are a function of DeltaE.
This is heresy in the 'science' of nutrition.
@Cliff
I don't think anyone thinks of Taubes as genius. Nor he of himself, as far as I can tell. Simply a very smart and studious journalist. What do stupid things do you he says?
As far as carbs driving insulin driving fat accumulation not being radical --- it is hardly widely accepted/mainstream - except by the Atkins folk - if it were, we wouldn't have a nutrition industry devoted to ceaselessly churning out useless diets du jour.
IMHO what drives obesity in this country is farm subsidies that subsidize high glycemic/carb foods, that drive their prices down, and not only do they taste good (I love me some McD's fries), but they are subsequently cheap, therefore demand is high - especially among the poor. The carb calories per dollar spent ratio at any fast food restaurant is ridiculously high. It is impossible for even a homeless person to starve to death, a few bucks a day, and he has more than enough to eat.
On a personal note, I have been eating a hyperlipid diet and have lost a large amount, very very rapidly. And no, I don't eat fewer calories than before.
Posted by: Varangy at Jun 4, 2008 10:39:51 AM
I have to weigh in on this topic from the Chinese medicine approach.
We define (excessive) weight gain as "phlegm damp accumulation" which is essentially adipose tissue with fluids mixed in.
The causes of phlegm-damp accumulation are numerous, including caloric intake, but as a few have already remarked, there is far more to weight gain than what you eat (or what you report you eat).
A few causes for pathological weight gain include:
1. Kidney/Spleen yang deficiency. This is going to look like a systemic and/or digestive metabolic lack ala hypothyroidism or post-antibiotic diarrhea. Kidney issues in TCM are often congenital or genetic by Western standards.
2. Food stagnation which is when the food we eat is more difficult to digest, giving rise to pathological byproducts (phlegm-damp) and ultimately weight gain and obesity. I have found fast food (targets teens), and that second tier of dietary nastiness mentioned above which targets 20-somethings (Applebees, TGIFridays, Olive Garden, Red Lobster, Outback etc.) serve up oodles of positively terrible food from a digestive efficiency standpoint. Deep fried, high caloric, fatty dipping sauces, etc. that all cause one to feel full for hours after the gastric contents should have emptied, or abdominal bloating for the same reason are the norm at this restaurants. Young people have a stronger, more vigorous metabolism and can often withstand the detriments of their dietary choices, but as we get older, you're going to feel the results of those dietary choices.
My personal fave is the supposedly healthy salad bar at Sizzler. My god, look at the average visitor to that restaurant. Seeing the obesity there actually makes me eat less! (And I live in a VERY health conscious area of Los Angeles.)
4. Liver/Spleen disharmony. This is essentially what happens when you're not calm while eating or digesting. The digestive process relies on parasympathetic nervous system activity. Fight-or-flight is sympathetic, and that turns off (or down regulates) the parasympathetic activities in the body such as digestion and reproductive activities (just to keep my post interesting.)
Chances are, you won't be able to eat or have sex very well when you're driving or in a hurry. Hence, fast food by definition stimulates sympathetic activation and the bright colors and environment of a fast food joint is going to lower your digestive efficiency leading again to weight gain.
There are a few other causes for phlegm-damp accumulation (obesity), but the point here is that caloric intake is only the tip of the iceberg, or should I say, only the frosting on the cake? :)
Posted by: Al at Jun 4, 2008 1:25:39 PM
Ultimately, USA is fat because we're O.K. with being fat. It's a choice. And a judgment that fatter is--or is not--acceptable.
yeah it's all those Americans who are totally ok with being fat who are spending billions of dollars a year on weight-loss products.
Posted by: ielerol at Jun 4, 2008 9:52:57 PM
Thanks for replying. It is more clear now that the Taubes hypothesis may be useful in describing behvaiour as driven by perception. It is more psychology than test-tube science. He's not offering better science, but a different way of looking at it. Kind of like the Chinese medicine angle. Each is useful within limits.
Y'all seem to miss the ceteris paribus clause. Or that to prove in the lab requires controlling for a single variable. Taubes needs to invoke the epicycles of appetite make his theory work. Yes, metabolism can adjust to intake to maintain what people call a “set point”. Composition of calories matter, too, as the energy is not transformed with equal efficiency. To tell me that eating less doesn't work is asking me to deny my own experience. That makes you (or Taubes) sound like a loon.
I could state it another way, maybe to square with Taubes's not-really-scientific explanation. Everybody knows that if they don't fully satisfy their hunger all the time, their pants will get looser. Regularly eating beyond hunger makes pants tighter. It is absurd (to my outlook) to remove willpower when the theory is founded on appetite (perceived hunger).
There seems a common ground that the USA diet has become more metabolically efficient (more simple carbs). Then perhaps that messes with the biological hunger signaling, and people eat more calories than their bodies are asking for. The actual biochemical process involves insulin perhaps as a primary signal carrier, but it seems nobody has a robust explanation of the whole mechanism.
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