December 30, 2011

Understanding Science

Revisit the causality of obesity

by Peter Attia

Read Time 3 minutes

I’ve written about obesity (i.e., unregulated horizontal growth) being caused by excess insulin, which in turn leads to overeating and under-moving.  This is contrasted with the reverse – overeating causing obesity.  Let’s double-click on this idea using one of the most important laws governing our universe – the First Law of Thermodynamics.

Whenever people like me or Gary Taubes or Rob Lustig say, “Calories-in-less-calories-out does not explain obesity,” we’re bombarded by folks screaming, “Hey – you’re violating the First Law of Thermodynamics…,” so let me address this point head on.

Below is the First Law in its simplest form.  It states that energy cannot be created or destroyed – that is, the change in energy of a system (blue term) is equal to the energy entering the system (red term) less the energy exiting the system (green term).  To make this specific to our question, let me state it this way: the change in fat mass of a person is equal to the difference between the energy consumed and the energy expended.

 

No one disagrees with this point (except maybe folks who think the world is flat or that the sun rotates around the earth).  Here is where the trouble starts…

Most obesity “experts” assume (erroneously) that the big equal sign between the blue and red terms implies a direction of causality.  In other words, they assume that an increase in fat mass (the blue side gets bigger), was CAUSED by the red number being bigger than the green number.

 

So is this the case?  Was the increase in fat mass CAUSED by more energy entering the system than leaving the system (i.e., was the gain of fat CAUSED by eating more calories than expending)?  If obesity is caused by overeating, the causation arrow points from right to left, as in the figure below.

 

Or is it the reverse? Was the positive energy balance (more energy entering the system than leaving the system) the RESULT of a change in fat mass?  In other words, does the drive to become obese (i.e., the drive to accumulate fat rather than oxidize it) cause over-eating?  If this is the case, the causation arrow points from left to right, as in the figure below.

 

Obviously, I believe the latter over the former, but the point is that neither argument commits the cardinal sin of “violating the First Law of Thermodynamics” as so many people assert when one suggests the “calories-in-less-calories-out-determines-change-in-fat-mass” model is incorrect.

To reiterate, I am not for a moment suggesting that energy balance or thermodynamics are being violated.  I’m saying they do not tell you WHY our bodies choose to accumulate fat instead of burn it.  A growing child, for example, is consuming more energy than he is expending (which allows him to grow), but this is not the CAUSE of his growth, it’s the RESULT of his growth.  A pregnant woman isn’t gaining fat during the pregnancy BECAUSE she is eating more energy than she’s expending. She’s creating a positive energy balance BECAUSE her hormones are driving her to create this energy balance so she can support the fetus.

Let me use one more example I’ll borrow from Gary Taubes to illustrate this subtle distinction. Look at the picture, below, of the crowded room.  Let’s explain what’s going on this room in terms of thermodynamics.  The First Law would say something like this: The change in the number of people in the room must be equal to the difference between the number of people entering the room and the number of people leaving the room.  For example, if the room “gains” 10 people, we can safely conclude that 10 more people entered the room than left it (e.g,. 15 versus 5, or 197 versus 187).

 

So here’s the million dollar question: Why is the room packed?  Let me be more specific, why are there 78 people in the room?  The “calories-in-minus-calories-out-model” says, “because 78 more people entered the room than left the room.”  I say, sure, that’s true, but it doesn’t tell me WHY?  I want to know WHY there are 78 people in the room (or, more specifically, WHY did 78 more people enter the room than leave the room)?  Was it because there was a very compelling speaker in the room?  Was it because they were giving away free food in room?  Was it because it was raining outside and folks wanted to stay dry?

If my goal is to keep people out of the proverbial room, I’d better understand what brought them into the room.  I need to know what is causing the room to accumulate people. Restating the First Law offers me nothing beyond the obvious. Of course more people entered the room than exited the room.  How does that help me get people out?

Similarly, when someone tells me so-and-so is obese because he eats more than he expends, I say, “of course he does…you’re just re-stating the First Law.”  What I want to know is, WHY did he eat more calories than he burned?  If we don’t understand this point, how can we treat this condition?

Photo by Alec Weir on Unsplash

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  1. Peter,

    Thank you for raising such good questions. I literally cried my eyes out watching your TED talk. I’ve been on the obesity roller coaster all my life. Twelve years ago I had ripping pain in my chest and because of my weight it was assumed I was having a heart attack. It took a couple days, an angiogram and CAT scan following a pulmonary crash to figure out it was a DVT – PE incident; I was 85% blocked. The doctor’s bias almost killed me by ignoring other potential causes to the pain in my chest. As it turns out, I have some genetic factors that make my blood more prone to clotting. All that to say, the medical establishment looks at obesity as a self-inflicted illness. I really appreciate your raising awareness of this bias in the medical community. As a result of this incident I’ve been on a quest for answers – most of which are coming from non-traditional sources outside mainstream medicine.

    I was recently exposed to the gut flora debate via Dr. Natasha Campbell-McBride. Her position is that the inputs and outputs are a function of how effectively our gut flora process the inputs. Many obese people are mal-nourished. Here supposition is that the damaged gut lining (from anti-biotics, lousy food etc.) is resulting in leaky gut syndrome. which is responsible for auto-immune issues and much more. I’ve been on her GAP diet for several months now and I am starting to loose weight and my lupus symptoms (diagnosed a year ago) are almost non-existent. How does this square up with thermodynamics? Her approach is not tied to calories at all. It’s about repairing the gut flora so the body can do what it was designed to do naturally; process food efficiently gleaning the needed nutrients and eliminating the rest.
    I’m sure you’ve seen this quote: Food is medicine = healthcare vs. Traditional medicine is actually “sick-care”

    Keep up the search for answers. Your humility is inspiring.

    • Edi, I’m so sorry to hear about your incident. Missed PE’s are a real problem. Someone very close to me lost his son (in his late 20’s) to a very badly missed PE. I think the gut plays a major role in this, and I’m eager to find out how changing foods can change the flora of the gut.

  2. If only the writer of this had a comments section. Alas, s/he has not. Otherwise, I would link to your blog. But I honestly don’t know whether to laugh or cry. Laugh, of course, because it’s so outrageously insulting. Cry because wrapped up in a white coat, a sideways glance, a snide comment and outright discrimination, this is the coarsest expression of what goes on in most people’s heads. Including the fat people themselves. Self hate is as epidemic as obesity.

    http://www.yourefatbecauseyourestupid.com/

    • Joan, I can understand how upsetting this is. Obviously, I share your feelings. I’m learning (the hard way) that the internet is a platform for a lot of idiots. Anyone with a keyboard, a fake name, an avatar picture, and a wordpress account can hide in their house and use their megaphone to spew anything they want. Whoever wrote this probably has the IQ of a carrot themselves, but more importantly, they are cowards. If they really had any guts or real conviction, they’d put themselves — and their ideas — on the line without hiding behind a blog that is probably read by 12 people a month.

  3. I really like this blog, it’s got a friendly, humanistic approach.

    However, please don’t discount the IQ of a carrot – or any vegetable for that matter! Those veggies are smarter than we think. Consider that the medical industry is constantly trying to work out a marketable equation, a “fix” for obesity, when vegetables will do the work for us. I think we’re focusing on the wrong equations entirely.

    One long-term remedy for obesity, and probably the best, is absolutely free: teach each other how to prepare, eat and enjoy a whole foods, primarily – or better yet – entirely plant-based diet.

    This sort of plan is wholly evolutionary: we’ve evolved eating this way; it’s also scientific: we can demonstrate its efficacy and health benefits over and over again; and like any beautiful theory: it’s amazingly simple to understand in terms of practice.

    Add some modest, sane exercise like walking to this equation and we’ve approaching a mathematical proof.

  4. Would C-Peptide levels make a better method of screening for the early stages of insulin resistance (as opposed to just getting a fasting glucose), or would that still be too incomplete? I suppose a better way to put it would be, have you run across any studies that have been able to demonstrate an effective way of catching IR very early?

  5. In your earlier post “Revisit the causality of obesity,” you said that “the change in energy of a system is equal to the energy entering the system less the energy exiting the system. …, No one disagrees with this point (except maybe folks who think the world is flat or that the sun rotates around the earth). “ In addition, similar principle is also applied in your post of “Do calories matter?”

    I cannot help to show my disagreement because it is only 50% correct. As a chemical engineer and spent my Ph.D. dissertation and whole career to simulate, control, and optimize the operation of chemical plants and refineries, a plant might explore if the operation is based on only energy balance.

    All chemical engineers require taking two semester fundamental courses of “Material and Energy Balance.” It is inaccurate to assume all consumed foods are for energy purpose because significant amount of metabolized proteins and fats are not used for energy but for protein or hormone syntheses, regenerations, etc. The synthesized hormones further control our body whether to be in an energy accumulation or expenditure mode.

    If you still disagree and if you do grow sprout seeds, could you use your energy balance to explain how a batch of sprouts increases weight by about 10 times in a few days by adding only zero calorie water and adsorbing no energy from light by placing it in a dark environment.

    The calorie balance theory has been used in medical and nutrition societies for so long, but it is an incomplete theory because it misses the material balance part.

    I do respect your efforts to search for the truth by jumping out of the conventional thinking patterns and I learn a lot from the sharing of your thinking and journey with the other people. My comment is not to challenge you, but just to show a different opinion from a person who has different background from yours. Even if we have different backgrounds, the science theories we learned should still be applied to each other.

    • Peter: Could you replace my previous comment with this one because it has a typo and unclear in some point of view?

      In your earlier post “Revisit the causality of obesity,” you said that “the change in energy of a system is equal to the energy entering the system less the energy exiting the system. …, No one disagrees with this point (except maybe folks who think the world is flat or that the sun rotates around the earth). “ In addition, similar principle is also applied in your post of “Do calories matter?”

      I cannot help to show my disagreement because it is only 50% correct. As a chemical engineer and spent my Ph.D. dissertation and 40-year career to simulate, control, and optimize the operation of chemical plants and refineries, a plant might exploded if the operation is based on only energy balance.

      All chemical engineers require taking two semester fundamental courses of “Material and Energy Balance.” It is inaccurate to assume all consumed foods are for energy consumption because (1) not all foods are digested, such as cholesterol ester as mentioned in your post; (2) significant amount of metabolized proteins and fats are not used for energy but for protein or hormone syntheses, regenerations, etc. Furthermore, different kind of material has different impacts on the hormone syntheses: some would promote energy accumulation and some would promote energy expenditure.

      If you still disagree and if you do grow sprouts, could you use your energy balance to explain how a batch of seeds increases weight by about 10 times in a few days and grow into sprouts by adding only zero calorie water and adsorbing no energy from light by placing it in a dark environment? (I don’t think all increased weight is from the water in the sprout. I am planning to find a dehydrator to prove my assumption.)

      The calorie balance theory has been used in medical and nutrition societies for so long, but it is an incomplete theory because it misses the material balance part.

      I do admire your efforts to search for the truth by jumping out of the conventional thinking patterns and I learn a lot from the sharing of your thoughts and journey with the other people. My comment is not to challenge you, but just to show a different opinion from a person who has quite a different background from yours. Even if we have different backgrounds, the science theories we learned from biology, physiology, chemistry, and physics, should still be applied to all of us. I hope I can correct my opinion if I can learn from your feedback.

    • After finishing reading your post of “Do calories matter?” it seems that we do not have any disagreement about the invalidity of the “Current Dogma,” and I totally agree with your explanation in “the Alternative Hypothesis.”

      I am sorry to react too quickly on your post of “Revisit the causality of obesity.” Your initial statement in the post led me to think that you agree with the current dogma that most people believe calorie balance is the only inviolable law. Yes, it is an inviolable law, but it cannot also violate the other law: material balance and both of them have to be satisfied simultaneously.

      It is the ignorance of the second law in medicine and nutrient fields for so long that causes so much confusions and problems because the second law of material balance can control our body to a total different homeostasis state, energy accumulation or expenditure state, even under the exact condition of the first law of energy balance.

      The only difference of my explanation to the problem is from a point of view which is obvious to all chemical engineers. However, it has been a puzzle to me why the physicians and scientists in medical and nutrient fields cannot see the problem for decades, even until now.

  6. Thanks for emphasizing that energy balance is not the only way to look at the causal mechanisms for why some youths become leaner or fatter than others. Recent evidence suggests that vigorous high-impact exercise stimulates immature stem cells to differentiate into lean tissue cells (i.e., bone and muscle) rather than fat cells, without necessarily influencing total body mass. Because lean tissue has a higher metabolic rate than fat tissue, leaner youths actually tend to ingest greater amounts of dietary energy and accompanying nutrients than fatter youths; i.e., the variation in body composition may cause the variation in energy intake. This evidence has been discussed in recent papers (e.g., Gutin, Research Quarterly for Exercise and Sport, 2013; Owens and Gutin, Current Cardiovascular Risk Reports, 2014; Cuenca-Garcia et al, Journal of Pediatrics, 2014).

  7. Hi Peter,

    This article shows some effect of excercise on long-term weight loss. http://www.bmj.com/content/348/bmj.g2646

    Any thoughts?

    Might people that move to a better diet (I don’t have access to the actual article to see the diet), just get more energy instead of being starved by their body on a high-carb diet?

  8. Hi Dr. Attia, 🙂

    As you know, I am a huge supporter of yourself and Gary Taubes 🙂

    I just wanted to post this to correct a lot of misinformation I see from CarbSane, Lyle McDonald, Colpo, and numerous other Blogosphere gurus- plus even some misinformation in the comment section here. So , so much wrong stuff that I feel necessary to publicly point out: This is for the benefit of your readers and it is from very top sources- some the best science educators in the world

    It is very well accepted among physicists that there is plenty of physics left that is undiscovered and not understood. Scientists , Paul Lutus and Nobel physicist, Dr. David Gross, correct the terminology . There is no such thing at all as a “scientific law.” The term “scientific principle” is far more accurate. And what “laws” mean. In science, “laws” are ALWAYS provisional and perfectible. Scientists expect modifications to be made in the future with progress. All “laws” are subject to being possibly wrong or modified. These “laws” are only the SHADOWS of a much deeper underlying reality. These “laws” are APPROXIMATIONS ONLY. It is difficult to say if they even exist in the same sense that the universe and physical reality exists.

    Dr. David Gross goes out of his way in a video to note this in an answer to ca child . Readers can Google ” Do The Laws Of Physics Even Exist David Gross”

    There is not anything about a “law” that makes it immutable as often claimed. That is not even a characteristic of law. Sure, they are well tested . But never , ever immutable. never beyond being perfectible and provisional. Every single thing in science is tentative. Everything.

    The conservation laws are from Emmy Norther’s Theorems. All the conservation of energy says , as Richard Feynman noted was that, ” there is a quantity in Nature, which we will call energy, that does not change in the manifold changes which nature undergoes.” However , as Feynman also notes it is an abstract mathematical concept . It EXPLAINS nothing at all. This is where CarbSane and her type go wrong. The first law of thermodynamics does not at all explain obesity. It is in the background and relevant but has zero explanatory power. relevant but not nearly SUFFICIENT. Not by a long shot.

    Physics is never done by fiat. So far, so good. What we are after is good “hard to vary explanations and deeply explanatory theories. Einstein’s THEORY was an UPGRADE to Newton’s “law” of universal gravitation. There is no hierarchy whatsoever between theories and principles or “laws.”Nothing is beyond reproach. Nothing. This is a critical point.

    The surest signs of unscientific people are those who think we have a complete understanding of any given phenomenon. This is why the criticism and attacks from CarbSane are easily a give away that her followers are full of bologna. Our understanding of obesity is very incomplete and much worse than other topics. s Feynman noted, science is wonderful but we only have a partial understanding of Nature. As Einstein said, we only see Nature only shows us the tail of the lion. We never ever know what is inside of an elaborate watch. We try to figure it out but can never open it.

    The responses from numerous top physicists specializing in non-equilibrium thermodynamics will be available from Adam from CalorieGate in his new post . He is a supporter of yourself and Gary Taubes. This will set the record straight as to what actual physicists say about obesity and conservation of energy. Namely, that this conservation of energy principle explains nothing about obesity. It is a biochemical phenomenon. Keep your eyes peeled 🙂

    The public will see how various Blogpshere gurus are completely musing the conservation of energy principle in an effort to blame and patronize obese people. The physicists say this is absolutely absurd and unscientific.Science can show us how we are wrong- and these gurus will be shown wrong

    Thanks for your good work .

    Best wishes,
    Raz

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