Faith - yes there will someday be a single hypothesis that will explain the obesity epidemic...someday, maybe not in our lifetime, but....IT WILL BE MULTIFACTORIAL!

Possible factors

• Hormonal (ala Taubes, et al)
• Reward (ala Guyenet, et al)
• Epigenetics (ala Cate Shanahan, et al)
• Neolithic Toxin consumption (ala KGH, Cordain, et al)
• Micronutrient deficiency (ala Paul Jaminet, et al)
• Energy balance (ala conventional wisdom)
• Mitochrondial dysfunction (ala J. Stanton, Peter at Hyperlipid)
• Psychological factors (ala Emily Deans)
• TBDs....if only we knew what those are

EDIT: Preemptive strike - the names I listed are just a few of players. Yes, there are others. The point of inclusion is that there are many people on the hunt. Maybe if we collaborate rather than compete, we can move this ball forward quicker.

Also, I do not currently agree with the carb--> insulin --> obesity paradigm. However, that low carb is effective as a therapeutic measure is not in question to me based on so many success stories. Do hormones matter...of course they do. So the point being that causation vs remediation are two related but different matters.

I like your post very much.

Maybe my little brain has a hard time grasping all of this, but...WHY DO SOME GURUS FEEL THE NEED TO PIMP THEIR HYPOTHESES AS "THE ONE TO RULE THEM ALL"?

You don't have to take very advanced biostats or mathematics to understand this simple concept: the reason multivariate regressions are done is because there are multiple variables. When it comes to human physiology, there are a bajillion variables, and when you add in environmental/emotional/etc factors and mix-and-match them, each person is going to be quite unique in the etiology of their weight gain.

I've gained weight eating fat, and lost weight eating fat. I've gained weight eating carbs, and lost weight eating carbs. I've tried lower food/tech reward and found it to be a nice way for me, personally, to reset some things that had spiraled out of control. Ketogenic diets also work great for me for certain purposes. But why try to push your individual experience or individual research on others?

If I remember correct, science increases in complexity as you go from the foundation on up: math to physics to chemistry to biology to physiology. Weight gain involves a bunch of those plus social factors. Why pretend to know all the answers? Everything is probably a little bit right. Except for healthywholegrains and arterycloggingsaturatedfat, that is.

No, there isn't a single hypothesis that covers ALL obesity.

But much of obesity has to do with the HPA axis dysregulation.

And there are lots of super-dysregulating paths that have not been a part of our thinking and discussion here..

There are many ways for the HPA axis to get dysregulated/inflammed, as well as for brain development to get very, very skewed (brain development is use dependent.) At certain times of your life prominently, for just one, in the early teens, your brain is busy pruning what I think of as neuronal "arbors" that are not used, and developing neuronal "arbors" like wildfire that ARE used. Depending upon what your brain is exposed to, this can be a big, big deal and spawn big, big problems. Just take one simple thought...we needn't get all fancy about this. What if your brain as a 14 year old is constantly experiencing insults due to the environment that make you spew cortisol(and other juicy chemicals!) like crazy. Do you think this might affect your brain? Do you think it is possible that these brain effects could be very wipespread, ie., affect more than one "function?"

So, let's look at some that we haven't looked at -

http://www.weightlosssurgerychannel.com/breaking-wls-news/childhood-obesity-often-linked-to-trauma.html/

Let me say that with this link, I do not agree with the conclusion, but I understand that the conclusion had to be "sold" to the general public on a TV station, so it had to be greatly simplified. Perhaps you can apply your super hacker brains to what might be the effects in the brains of these people whose brains were bathed in at least cortisol, people who could be described as never feeling safe. Might they have developed some cortisol related conditions? Might an outcome of their brains being bathed in cortisol ad infinitum have led to the inflammation of the HPA that we know occurs through a variety of mechanisims, leading to probable depression, anxiety and other states originating at young ages, AND a high probability, in my opinion, of lots of endocrine system disruption/dyregulation that can greatly affect energy use and appetite/feelings of hunger?

http://www.nospank.net/stevens.htm

In this link, I think that their projection that trauma (think: brain changes) becomes a path to obesity for about 8% of the obese is probably conservative. But still, combine that with Lustig's identification/defining of a syndrome of vagally mediated beta cell hyperactivity that leads to insulin hypersecretion and obesity and which is treated by insulin suppression, a phenomenon which may occur in about 20% of the obese population, and we are now batting about 28% of the obese population.That's a big chunk of the total.

http://www.chc.ucsf.edu/coast/faculty_lustig.htm

Now, take a think on the following...The purpose of this "answer" (the entire post, including all of the above) is not to be an "answer." It is to broaden the thought pool for thinking about the question.

"This study not only confirms that ADHD is a highly prevalent condition in severely obese patients, but that the treatment of ADHD is associated with significant long-term weight loss in individuals with a lengthy history of weight loss failure.

Levy suggests, as I did in earlier postings on this topic, that ADHD should be considered as a primary cause of weight loss failure in obese patients."

http://www.drsharma.ca/still-more-on-adhd-and-obesity.html

"Attention deficit disorder with or without hyperactivity (ADD or ADHD) and impulsiveness has been associated with increased risk for weight gain in both children and adults. In one study, ADHD was present in over 25% of all obese patients and 40% of patients with class III obesity. Reasons for this prevalent co-morbidity are unknown, but brain dopamine or insulin receptor activity may be involved.

Patients with ADD or ADHD usually manifest a long history (since childhood) of impulsivity, lack of concentration, decreased attention, inability to complete tasks, impairment in school or work performance and social dysfunction. Being “hyperactive” in the sense of the DSM-IV diagnosis of ADHD does not prevent the development or persistence of overweight and obesity in children."

http://www.drsharma.ca/obesity-attention-deficit-disorder.html

"Regular readers will recall that almost 30% of adults with severe obesity may have signs of attention deficit hyperactivity disorder (ADHD) and, when present, this can be a major barrier to weight management."

http://www.drsharma.ca/obesity-cognitive-behavioural-therapy-for-attention-deficit-disorder.html

"Childhood maltreatment or adverse experiences in five domains (emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect) have been reported as highly prevalent in patients with binge-eating syndrome. In one study, 83% of patients with binge eating reported some form of childhood maltreatment: 59% reported emotional abuse, 36% reported physical abuse, 30% reported sexual abuse, 69% reported emotional neglect, and 49% reported physical neglect."

http://www.drsharma.ca/obesity-abuse-neglect-and-post-traumatic-stress.html

Now, some more nice science background from one of the best of the best:

"Childhood is a dangerous time." "The home is the most violent place in America."

http://www.lfcc.on.ca/Perry_Core_Concepts_Violence_and_Childhood.pdf

"We are not designed for this modern world. The human brain is designed for the natural world. Small, multi-generational family groups living together."

http://www.mentalhealthconnection.org/pdfs/perry-2009-presentation.pdf

http://www.healing-arts.org/tir/perry_childhood_trauma_the_neurobilogy_of_adaptation_states.pdf

And a piece of PubMed research, because PubMed excites us so:

http://www.ncbi.nlm.nih.gov/pubmed/18193182

http://www.ncbi.nlm.nih.gov/pubmed/15761171

http://www.uppitysciencechick.com/rohde_abuse_dep_obesity.pdf

For those who are prone to deeming the "psychological" to being "all in the head," be very, very clear that I disagree with you. And so does science.

With imaging, changes in the brain can be seen. Changes in the brain resulting from psychotherapy, which for too long was seen as another "all in the head" therapy, can also be seen/measured.

http://www.psychiatrictimes.com/display/article/10168/1926705

And to be really, really clear, nowhere in this post am I saying that if you are or have been a significantly overweight or obese person, that YOU suffered childhood trauma, have ADHD, or have suffered other linked adverse experiences.

This is a response to the question. And as I made clear from the outset, I do not buy into any single hypothesis for obesity, though I see some as far more compelling than others.

The purpose of this answer is to broaden the thinking field.

It is not to "prove" the information that I have presented, which is simply to get the "wheels turning."

I will leave you with a favorite quote:

"If 20 million people were infected by a virus that caused anxiety, impulsivity, aggression, sleep problems, depression, respiratory and heart problems, vulnerability to substance abuse, antisocial and criminal behavior, retardation and school failure, we would consider it an urgent public health crisis.(This was written in the mid 90's. Were Perry writing it now, he'd add obesity, I am sure.)

Yet, in the United States alone, there are more than 20 million abused, neglected and traumatized children vulnerable to these problems. Our society has yet to recognize this epidemic, let alone develop an immunization strategy." - Bruce D. Perry MD., PhD, The Child Trauma Academy

.

Our bodies and minds have evolved to respond to the properties of certain foods (and activities) that trigger hormonal, physiological and neurological responses within.

We are now eating foods that have been engineered to stimulate a subset of particular responses, but do not carry the nutritional payload expected by the body for that particular 'food signature'.

EDIT: Food engineers target those responses that translate to economic gain for the food-manufacturer.

You can imagine how in our evolutionary past Hebbian learning would tightly bind the nutritional quality of food and palate/taste...and perhaps even activity (predators hunt when hungry, whereas we jog having carbed-up).

Activity and lifestyle are also important factors - not to burn off energy, rather as a mechanism with which our body can understand the world - through energy expenditure and so forth.

How can I best summarise this....if someone opened up a computer and chucked a load of seawater in to it how would you work out which bit got destroyed first? The motherboard? CPU? RAM? Some other bit? By this I mean that there are several important functions within the body - not simply organs, but also messaging systems in the form of hormonal cascades and so forth. You can screw up any one of them, or several at the same time - and cause deleterous effects 'downstream'....be wise with your choice of 'inputs'.

When I look at factory company photos from the 1920s through the 60s with all the employees lined up on risers, there is never a fat, obese, slightly overweight employee...ever.

They ate real food like lard, butter, beef, chicken, unadulterated veggies and no fruit from places other than the local environs. No hybridized dwarf wheat, no hydrogenated anything, no margarine, none of the unpronounceable ingredients on packaged "foods", no soybean,canola,veg,saffower or other frankenstein oils.

The one hypothesis that makes sense to me is the introduction of "foods" that our bodies only know how to store. And that has only happened since the mid sixties.

We are living the legacy of Ancel Keys and the lipid hypothesis that eating fat will kill you.

That is the only hypothesis that works for the advent of obesity. Take away neolithic foods and the obesity epidemic would abate.

I wonder if part of finding the one-hypothesis-fits-all will be a series of trials with human volunteers of at least 2 types: healthy folks with great metabolism and obese folks with clearly deranged metabolism. I'm thinking the easier challenge would be showing that the deranged metabolism can be shifted back to healthy using the hypothesis, but the tougher challenge would be shifting healthy subjects to a "sick" metabolism (and back) due to ethical issues.

Anyhow, if you can't affect metabolism in predictable ways how can you prove a hypothesis?

I had thought about posting this as a question, but any port in a storm. Here's my hypothesis.

Obesity is caused by fast food.

Feel free to gut it, but here's why I believe it, in short form. Easy food accessibility, fast eating, and good flavor result in overconsumption before satiation can happen physiologically. Super Size Me illustrates the hypothesis.

The techno body-as-chemistry-lab hypotheses are just not broad enough to describe obesity as a social phenomena. We're not gathered on the game trails anymore because it's so easy to use the drive throughs.

Hi Beth ... Just to clarify my position, I do NOT believe there is a single hypothesis that can explain obesity. Indeed to say there is one single hypothesis is downright ridiculous in my opinion. Perhaps I need to be more careful in my wording there, because when we're talking about obesity hypotheses these days, the focus is basically on the epidemic. Specifically: Why did obesity rates snowball from sometime in the late 70's to mid 80's?

This is where Taubes' hypothesis fails before it even comes out of the gate. I grew up during that time so I know what we ate as kids that did not make us all rolly polly pudge balls. Back when "kid's cereals" went by names like Sugar Frosted Flakes ... and kids put more sugar on top of that.

So let me rephrase a bit and say that any theory of modern obesity must be consistent with the observation of the obesity epidemic we are seeing. It does not need to explain all of it, but it must be consistent with it at the very least.

In this regard, Stephan Guyenet's rendering of food reward comes closest but doesn't account for what I believe to be other factors. Perhaps this is why he called it A dominant factor. Activity does play a role, and I'm not talking exercise, I'm talking little stuff that adds up. Taubes doubled down in WWGF. It's the carbs, insulin, only the carbs, and calories have nothing to do with it. Dietary fat has no influence on body weight.

It is really basic. We have, in our society a combination of unlimited food availability, in most cases, and no requirement to expend energy in order to get the food. We don't pick it, catch it, chase it..........we just buy it. Your body uses energy. When you move more, it uses more energy. If you can walk into a store, reach into your pocket and pay someone for it, you haven't expended much energy in relation to the caloric intake. It's really that simple. Lots of information about this subject at www.PrimitiveHealth.blogspot.com

Beth this is a great question and plus one for asking it. My answer is short. No I don't see it that way at all. It is many domino's hitting our biochemistry often and sequentially that erodes efficiency.

I think Taubes does a better job of explaining how people don't get lean or get flabby vs. actually get obese. Presently, I'm convinced that it's the result of the massive recent increase in dietary excitotoxic amino acids (typically in the form of MSG and aspartame) that damage the leptin receptors of the hypothalamus' arcuate nucleus (which is unshielded by the blood-brain barrier).

Three words: Taubes Taubes Taubes.

EDITED TO ADD:

The question is, what caused the epidemic, which means we can ignore the baseline rate of obesity that existed in statistical studies before the advent of the epidemic. Thyroid problems? Ignore 'em! Pituitary problem? Fuggetaboutit!

That stuff does NOT count!

What counts is, the low-fat high-carb heart-healthy propaganda that sent the whole nation into a death march. That's what counts!