Obesity - What is the real problem?

 

To me it seems critical that we get a realistic and accurate sense of the overall problem, since much of the difficulty is confusion regarding how to think of it in the face of seemingly conflicting information.  I am going to offer my understanding of the scientific consensus as a framework.   

 

For all the confusion we often have over various aspects of nutrition and fitness, I think there are a handful of principles that are particularly reliable based on the evidence we have so far.  

 

The reason so many people around the world have been getting so much fatter so quickly is that they are taking in more energy than their bodies need in order to be nourished and satisfied.  And they do this for reasons that they are mostly unaware of having to do with reward, preference, palatability, expectancy, reliance on cues, and satiety.  Let's call this the mindless surplus intake theory of obesity. 

 

As intuitive as it might seem at first, the mindless surplus intake theory of obesity doesn't have to be true.  There could be other reasons for our growing fatness.  Our bodies or environment might have changed to make many of us store fat more efficiently from the same amount of energy intake (the broken metabolism theory of obesity).  A number of authors in recent years have promoted variations of the broken metabolism theory.  The broken metabolism theory sounds scientific and some variations of it have been promoted with long lists of research citations or even with the limited blessing of some researchers, especially when it is combined with reasonable actionable advice as well.  In general though it seems to me that the "broken metabolism" theory itself has been pretty thoroughly falsified as a primary driver of obesity.  And that fact matters in some  important ways.

 

Our bodies or environment might also have changed to make many of us more impulsive about eating  and we have failed to compensate by exercising our willpower adequately (the gluttony theory of obesity).  Similarly, our bodies or environment might have changed to cause us to be less motivated to move and we have failed to compensate by exercising our willpower adequately (the laziness theory of obesity).  The gluttony and laziness theories are compelling to us individually because we have a strong intuitive sense of the importance of personal responsibility, and self-control is indeed a powerful factor in success across many endeavors.  However the laziness and gluttony theories exaggerate the role of deliberate self-control in the myriad decisions we make every day about eating and activity.  People successful at controlling their weight use their self-control not to make every decision deliberately but to create better habits for themselves and shape their environment to help them.  It is not a failure of willpower that drives obesity.  That fact also matters in some very important ways. 

 

Our bodies or environment might also have changed to cause us to need less food while still eating  enough to create a surplus (the inactivity theory of obesity).   Activity levels contribute significantly to both health and obesity, and especially to the maintenance of healthy weight, but we know the driver of obesity is mostly intake and that just moving more without also cutting back energy intake doesn't reverse weight gain in the obese in general.  This is almost certainly a major factor in both health and obesity, but it is clear from the existing evidence that it is not the primary driver of obesity.  The trend in fatness corresponds far more closely to changes in intake than changes in activity.  Also the experimental evidence shows activity being far more useful for maintaining weight loss than for simply "burning off calories" in most people, largely because we often tend to eat more to compensate for exercising.

 

In addition, more than one of these might be a factor.  But from my reading of the evidence patterns, the primary driver of obesity is now clear.   We have been taking in increasingly more energy than we need, mostly because we have been eating more than we would need to fuel our activities and nourish our minds and bodies.    And we have been doing this for reasons that do not involve the specific discretionary macronutrients we eat most of (e.g. carbs vs. fats), do not involve us simply failing at deliberate self-control, and do not involve us having inadequate knowledge of which diets are best for weight loss. 

 

What are these mysterious reasons for creeping intake if it is not eating too much fat or too much sugar or too much starch in particular as many authors have claimed?

 

1. Our intake is regulated primarily by mechanisms of reward, preference, palatability, expectancy, reliance on cues, and satiety.  We learn what to eat and how much based largely on stimulus cues, what we expect from food, how palatable foods are to us, and how they make us feel.
2. Our reward and satiety mechanisms are optimized for regulating our weight under natural stimulus conditions by relying primarily on volume and weight of food and secondarily on energy content.  We mostly tend to eat about the same volume of equally palatable and rewarding foods every day.  
3. Our metabolism is optimized for efficiency of energy storage rather than for maintaining a stable weight.
4. We are bad at estimating how much energy we need in order to be nourished and feel satisfied.
5. We are bad at estimating how much energy we are taking in in order to compensate for well-engineered distortions of reward and palatability.
6. We have come to rely increasingly on cues in our environment to determine how much energy we need and how much we are taking in
7. We have come to increasingly exploit our reliance on cues in our environment in order to market food and health and fitness products, and this distorts the cues we rely upon so heavily
8. We have come to increasingly rely on strategies which overemphasize small or irrelevant metabolic effects, rely on outdated theories, rely on willpower, ignore the long term, and in general are unsustainable and make us feel like failures when we can't sustain them.  

 

If my understanding of the scientific consensus is correct, the mindless surplus intake theory of obesity reflects it well and can be understood in more detail in terms of the satisfaction theory of intake regulation.   This says that we eat mostly what satisfies us because of the way the reward and satiety mechanisms work in our nervous system rather than because of metabolic or nutritional effects.   What gets "broken" in obesity in general is that we stop being satisfied with a nourishing amount of food and we keep eating even though we are taking in more than we need.  The reasons for this have little directly to do with willpower or carbs or fats and everything to do with the mechanisms of  reward, preference, palatability, and satiety.

Why is the problem of obesity so damned tricky?

1. Why is the problem of obesity so damned tricky?

 

A lot of us are fat. Fatness increased dramatically in the 20th century, especially since the 1980's in the US.  We don't like being fat in general.  When it becomes extreme, body fat usually doesn't look good to us and can lead to health problems, diminished longevity, and restricted quality of life.  Some distributions of body fat are worse than others for health or for appearance, but at some point it eventually looks bad to us and detracts from our lives.  

 

1. Just Theories are Well Communicated and Popular but Wrong

 

If we find fat so problematic, why haven't we simply found good solutions for it and begun to apply them?  Most people can lose some body fat temporarily by some combination of depriving themselves of some particular kinds of preferred foods, trying to force themselves to eat less,  and trying to force themselves to be more active.  Most people end up going back to their original body fat levels, or greater, after a few weeks, months, or years of that effort.    There is no lack of simplistic just theories about why this is happening:

 

Fat people are just lazy and not exercising enough self-control over their eating and exercise

Fat people are just gluttons who eat too much

Fat people are just eating too much carbohydrate

Fat people are just eating too much starch

Fat people are just eating too much sugar

Fat people are just eating too much fat

Fat people are just maintaining their weight at a genetic set point

 

Although each of those ideas is wrong in its own particular way, and they are each perhaps partly right in some sense,  it is the just part that is most wrong of all.  The just theory is a special kind of problem in itself that is part of the reason fatness is so difficult to address.

 

Here's my central claim: scientific consensus is not just a matter of certain opinions winning out over others, the problem of obesity is understood in broad form as a scientific consensus even though many the details are complex and some of our knowledge of the factors is undoubtedly incomplete.  There is a rough scientific consensus about various aspects of obesity across fields of physiology, nutrition, psychology, neuroscience, and medicine.  It is not just the confusing mess that appears in popular media.

 

I also claim: this consensus understanding is not what is published in most diet, fitness, and weight control books.  In fact, a sizable number of popular books on diet and weight control conflict dramatically with the scientific consensus, but are marketed as if they were new and revolutionary new findings.    This has contributed heavily to the confusion and so added to the problem. 

 

 

B. The Scientific Consensus is Poorly Communicated

 

In the stories that journalists tell to try to communicate their own interpretations of the obesity and health research, they have often engaged the science compellingly but not faithfully.  We now know some very useful things that are not well communicated, or are even ignored or denied by popular authors with their own agendas, or get lost in the media confusion:

 

1. The theory that people can control their weight by exercising self-control at each eating or activity decision is simply wrong.  

 

No one has that much self-control against an environment that constantly tempts them.  The psychological study of self-control reveals that variation in impulsiveness is indeed a factor in all sorts of problems, including obesity, and that people can often learn skills to compensate for impulsiveness, but these do not rely on individual acts of self-control.  Self-control is always finite, and we successfully compensate for impulsiveness by not just exercising self-control in each decision, but also even more importantly by altering our environment and altering our habits so that we reduce the need to exercise our always finite capacity for self-control.

 

2. All of the theories of specific  macronutrients causing  us to become fat are simply wrong.

 

The theories of metabolic advantages of particular diets (low carb, low fat, vegan, paleo, etc.) have all been falsified scientifically so far.  Obesity is in general at the population level not caused by everyone's metabolism being "broken" by certain foods nor is it "fixed" by eating certain foods. 

 

We know for a fact for example that low carb diets do not cause people to lose weight by any special "fat burning mode" as is often claimed in popular diet books.   We know that simply eating a lot of fat or a lot of sugar while keeping energy intake constant does not cause us to gain more body fat.  We know for a fact that the theory of obesity being caused by insulin levels rising due to eating  too much starch or sugar is simply wrong.  People become fat when they take in too much energy regardless of the source and they lose body fat when they take in less energy regardless of the sources they eat less of. 

 

That doesn't mean people respond equally to every kind of diet.  It's just that the reasons are not metabolic.  The reasons have to do with reward, satiety, and sometimes individual differences.  But the metabolic differences between different macronutrient strategies is based on thinking that has already been tested and falsified.  

 

Also  this wouldn't have to be true necessarily.  It isn't a logical necessity that foods have no powerful differential effect on absorption and conversion to fat and fat storage.  It's not just a matter of thermodynamics or conversation of mass and energy.  It is possible that our biology might have allowed us to take in some kids of nutrient, extract energy or chemicals from it, and excrete most of it without gaining body fat.  But it turns out to be false.  The reason is not conservation of mass and energy, the reason that our biology is particularly efficient in using nutrients and in storing the surplus energy. 

 

We might truly have discovered some  differential metabolic effects that prevent us from processing certain foods into fat (and that is exactly what many popular authors have claimed) but … it turns out that it doesn't seem to be true in general, and certainly not as a reliable  way to lose body fat permanently.  The small differential effects of nutrients on metabolism are sometimes used to good effect in short term efforts at bodybuilding and fitness, but they are not a reliable approach to obesity in general.

 

3. Consequently, No macronutrient restriction strategy is a best practice diet for everyone. 

 

Framing the problem of fatness as if we  need to choose between popular branded diets is more often part of the problem than part of the solution.  Branded diets are generally based on a particular just theory.  

 

Debates over low carb, low fat, low sugar, low starch, low glycemic, high fiber, vegan, paleo, and so on are mostly based on asking the wrong question: "what specific food is making me fat?" 

 

Cutting out problematic "trigger" foods can be helpful for particular people, but not for metabolic reasons.  Also cutting out entire classes of food can help at least temporarily lose weight.  This is also not for metabolic reasons.  This is because we tend to reduce intake more than we compensate, at least for a while, when we cut out entire classes of food. 

 

Some of those strategies work better than others in the short run.  But it turns out with those macronutrient restriction strategies that it really doesn't matter which class we chose to cut out in the long run. 

 

People who successfully reduce intake by restricting carbohydrates and people who successfully reduce intake by eating vegan or by eating "paleo" are all losing weight because they are taking in less energy, not because of metabolic advantages. 

 

So long as we can sustain the calorie deficit with that strategy, we lose body fat.  That's wonderful for the people who end up with a strategy they can sustain, and we can find some success stories for many different strategies.  Strategies that restrict entire classes of nutrients end up being unsustainable for most people  in the long run though and the claims often made about any of these having unique metabolic advantages for weight control have been soundly falsified.  

 

4. People do not regulate their weight to a particular inherited set point.

 

This is the opposite problem from the panacea solutions.  This one reinforces our tendency to give up.  Fatness and leanness often run in families, but not because our genes have a built in weight that we are fated to maintain.  It is because of all of the various factors that go into activity, reward, impulse control, individual metabolism, and habit formation, how those interact with specific environments, and because we often inherit things in addition to our genes.  Animals in their native ecological niche tend to regulate their weight very tightly and people who try to lose weight often end up back at the same weight.  But these are as much a result of stable aspects of their environments as stability in their weight regulation.  When we re-engineer out environments we end up altering weight regulation.  The efficiency of our biology and the stability of our dispositions are powerful factors in making obesity a difficult problem but they do not  make it impossible to solve. 

 

I'm going to try to do more than just add my own personal just theory to the already confusing and conflicting list.  What I'm going to try to do is navigate the available evidence to show what is going on and make sense of why the problem is so difficult and what people are doing when they do manage to succeed.

 

3. The Backlash Culture Against Obesity Does More Harm Than Good

 

So the "obesity epidemic," as it has often been called, has led to a culture of backlash against fatness.  By that I mean a commonly shared negative attitude toward fatness and toward fat people.  We have mobilized mightily against the problem in all sorts of ways.  Some of those have unfortunately probably made the problem worse. 

 

The backlash against fatness might have been a good thing if it had led to a problem solving culture that recognized the biological, psychological, cultural, and economic dimensions problem realistically, helped us understand it, and began providing realistic solutions.  Obesity researchers have sometimes attempted to offer realistic solutions, especially focusing on preventing obesity in children where we can potentially have the most effect.   

 

But realistic problem solving is definitely not most of what has happened so far.   What we have instead is:

 

1. The problem remains: most people who try to lose body fat end up going from diet to diet or from one exercise program to another , succeed for a while, and then give up.  Eventually many give up on the problem entirely as hopeless.  In effect, we often give up on ourselves.  This is especially true when we buy in to the popular misconception that obesity reflects a simple failure of willpower.  Fat people are often stigmatized as lazy and they feel like failures, which generally makes the problem worse rather than better.

 

2. The food industry exploits the situation by creating and marketing niche "diet" and "health" products that supposedly address the problem but which rely on outdated theories, popular misconceptions, and strategically selective interpretations of research.  The market for high density rewarding "diet" foods for example was created to exploit medical advice to eat less food by eating less fat.  The advice was oversimplified and the new market for diet foods probably added to the problem significantly by exploiting it.  Their goal is selling more food product rather than improving health, which most often turn out to be conflicting priorities.     They become part of the problem by flooding us with false solutions and misleading information. 

 

3. The fitness industry exploits the situation by creating complex dietary and exercise programs that are oriented to short term bodybuilding or fitness goals and then marketing those as solutions to obesity. 

 

4. Popular authors tout their range of idiosyncratic interpretations and solutions, each trying to make sense of the confusion but they mostly end up increasing it.  Popular diet just theories by journalists and doctors very often end up inadvertently creating even more confusion.  

 

So the backlash culture in these various dimensions,  far from helping to lessen the problem, has exacerbated and perpetuated it in several specific ways:

 

• It increases the difficulty of the problem for individuals psychologically, by fostering confusion and then discouragement and self-loathing.  By emphasizing willpower in unrealistic ways, and relying on solutions that require extraordinary short term efforts, we make people less able to succeed rather than more able to succeed in the long run.

 

• It adds to choice confusion when we try to make decisions and are led astray by the marketing of product rather than decisions in our own best interests.  Unless things like "diet foods" and "bootcamps" and "extreme weight loss" are themselves actually viable solutions to obesity (which they are not in general) they become new sources of both confusion and discouragement.

 

• It reinforces the epistemological problem of cynicism.  Thinking we are all scientific experts  who are well situated to simply choose between the popular diets and popular theories that seem most plausible to us prevents us from learning from the actual research and prevents us from moving toward more realistic solutions.  We become easy prey for every scheme that comes along. 

D. Science Cynicism and Overly Broad Mistrust of Expertise

 

Journalists writing about the problem of obesity have responded to this ongoing confusion by either claiming we don't know what causes obesity or by trying to promote a particular new finding.  The problem is very complex in some ways, but it is very misleading to say that we don't know enough about it to move toward better solutions.  The journalists who say we don't know the answer are a minor concern though, they are at least sincerely trying to be good communicators of the science and clear up the confusion.  The ones who are really dangerous are the grandiose prophets of false information. 

 

What we usually have is a theory that catches the interest of the journalist and then they confirm it by gathering information and telling stories that reinforce their own theory.  This is a compelling and powerful way to communicate, but it offers no assurance that they are getting the science right.  And while we sometimes find out about truly revolutionary ideas this way, as it turns out, these "sciencey" storytellers are most often getting as much of the science wrong as they are getting right.   

 

These "sciencey" journalists often end up asking bad questions and then we end up talking about the wrong things.  I think this is a big part of the problem and the reason I have written this book.  I hope to describe what we know about the problem of fatness without falling into the common trap of arrogance and confirmatory bias, but of course I can only argue my own perspective.  I could be wrong about the scientific consensus, but I will do my best to communicate it as faithfully as I can. 

 

The unconstrained confirmatory bias by journalists wouldn't be so bad by itself in some cases, since they do sometimes bring information to light that was not previously well known.  At least some people would benefit from some of this information.    But these folks often then read some scientific literature to try to bolster their articles and books and I feel they often do a hatchet job on it.  They can't reconcile their idiosyncratic theories with the existing evidence so they start claiming that the evidence that conflicts with their own theory was due to "corrupt researchers."  This ad hominem strategy has been a highly successful one for some authors, but it is an unfair way to argue and much worse, it plays into general cultural cynicism of science.  That part is extremely bad for the rest us.  It means we perceive the science as arbitrary or a matter of choosing sides based on what sounds plausible or what seems to work for some people.  It feeds the popular trend for imagining that everyone is naturally capable of evaluating scientific evidence by virtue of "common sense." 

 

What often happens, I believe, is that we end up mistrusting expertise, which is in itself a very serious problem.   That fact that we find so many false or misleading claims of expertise makes the problem of finding, trusting, and interpreting legitimate expertise even more of a challenge.    Nutrition and health sometimes involve on complex technical knowledge and interpreting rich patterns of seemingly conflicting evidence.  This kind of interpretative skill and knowledge is not something we possess as part of our "common sense."  It is something that requires not only understanding "critical thinking" in general, but also requires domain-specific knowledge in the specific fields in question. 

 

The backlash culture and especially cynicism of real expertise has fed bias and arrogance by various popular journalists who then set the tone for popular conversations in unproductive ways.  Although they may have a lot of charts and graphs and selectively cite and interpret a lot of research, rarely do journalists engage the research deeply and competently and systematically and put it into context.  Rarely do they make a distinction between different kinds of evidence and different quality of evidence in order to do a skilled job or drawing general conclusions from the existing science. 

 

The biggest problem with many of these popular authors is their grandiosity.  They think they've discovered a pattern that everyone else has missed or they have some limited success with some people and they proclaim to the world that they have the solution.  Grandiosity exploits uncertainty and cynicism to produce cults of misinformation that are self-perpetuating and extremely difficult to address with reasoning and evidence.  

 

 

Summary of Why the Big Fat Problem is So Tricky

 

Summary of broad factors making the Big Fat Problem so nasty:

 

Problem Factor	Class of Factor	Associated Bad Thinking
We tend to think in terms of simple actionable heuristics we can act upon when we make decisions.  What food is causing me to get fat, so I can stop eating it and lose weight?  What foods should I eat to lose weight instead?  Our need for actionable heuristics makes us especially vulnerable to just theories, and just theories of complex outcomes are typically wrong.	Oversimplification	"Obesity is just a matter of eating more of … or eating less of  …"
The science is often distorted into oversimplified advice.  The scientific consensus relies on expertise to understand and is hard to communicate in terms of actionable steps so it gets lost in the confusion of just theories.   We end up systematically asking the wrong questions and arguing without regard to the existing patterns of evidence.	Oversimplification	"One study constantly contradicts the previous one, so it's all really useless information, we should just pick the authors we agree with and follow their advice"
Our collective cultural assault on fatness has led to a backlash culture that makes things worse and leads to additional problems.	Unintended Consequences	"Being fat is really bad, stop being so lazy!  Just do this… "
Journalistic arrogance and widespread science cynicism exploit the problem of ubiquitous expertise	Knowledge Cynicism	"We're all scientific experts, including me!  Forget the scientific consensus, this sounds like a good way, follow me!"
"Sciencey" storytelling journalism	Poor science communication	"Telling stories about research and researchers is a great way to learn the science!  The details of weighing evidence are boring and irrelevant and people aren't able to handle it."
Industry interests driven by economic and business concerns that often end up conflicting with public health or individual interests of consumers	Economically Driven Consumer Culture	"People citing research in their ads and branding their products for health are generally offering valuable new choices for us."