Obesity is the result of a caloric surplus. Cavemen didn't have that luxury.
Obesity epidemic is a very recent phenomenon. Are you arguing that there were no societies that had caloric surplus up until late in the XX century?
Or would you say that American Samoa with obesity levels of 70% [1] somehow have the luxury of having calorie surplus, while people of Switzerland (8.2% obesity) are struggling to get enough food?
Speaking about Paleo diet in particular, why don't those guys gorge themselves into obesity [2]?
The Kitavan people have been under greater study for their remarkable health characteristics. The people show no indication of coronary heart disease, stroke, diabetes, dementia, congestive heart failure, acne, low or high blood pressure, or obesity. There is also almost no indication of cancer.
The Kitavans have abundant food supply and are not threatened by malnutrition or famine.
> Are you arguing that there were no societies that had caloric surplus up until late in the XX century?
No, only that a caloric surplus is necessary to gain weight. Matter cannot be created from nothing, a surplus of energy is required to perform all the bodily functions and to also build body mass.
A people can have an abundance of food and still not get obese, if they simply don't eat too much of it, relative to their caloric expenditure.
Do we know that? I thought there was some research indicating the hunter-gatherer societies actually had to devote rather little (comparative) time to gathering sustenance.[1]
Is there some research I should be aware of that refutes this, or at least asserts more information as to a likelihood one way or the other?
Your assumption about the laws of thermodynamics predicates that the "Energy out" part of the equation is not somehow effected by the type of "Energy in" (Adding wet sticks to a fire will not produce as much released energy as adding dry sticks or gasoline soaked sticks)
The general argument about carbs or any food with high glycemic response is that these foods are like adding "wet sticks" to the fire. There's considerable science and anicdote to support this.
If you're interested (And not simply not throwing around pithy sound bytes about physics) check out:
Why we get fat (And what to do about it) By Gary Taubes (http://garytaubes.com/)
For some very compelling anicdotal evidence (That also supports some concepts of Paleo) check out http://www.reddit.com/r/keto
Your metaphor of adding wet sticks to a fire is flawed, from a thermodynamics argument. Assuming that the fire is large enough, it will dry out the wet sticks through evaporation/boiling, and the wood's total contribution to the heat ("energy out") will be unchanged.
Now, of course for the people sitting around the fire, some of the heat that would be warming them up or used for cooking is instead used to force a phase change in the water, so it won't be as much "useful" heat, but that meaning of utility - which I believe is the one you want - is outside of thermodynamics.
For what it's worth, "for some very compelling anecdotal evidence" of the thermodynamic approach, see The Hacker's Diet at http://www.fourmilab.ch/hackdiet/ , which uses the "Rubber Bag" model. Unlike the garytaubes.com web site, the entire book and supporting materials are available for free download. The basic premise is the thermodynamic "if you eat more calories than you burn, you gain weight; if you eat fewer calories than you burn, you lose weight." (See also 'Food and fact' where "The rubber bag view of the body and considering only the calorie content of food is obviously oversimplified." and some of the complications are mentioned.)
I believe you are making a different argument, which is that you can't always measure the caloric impact of foods. Under the Hacker Diet, that makes little difference. It uses a feedback system based on weight trends rather than specific calorie counting. There's no need to know that oak combustion produces about 15MJ/kg and boiling water from room temperature takes about 3MJ/kg, because it only looks at 'is there enough heat'?
Thanks for the links on the Hacker diet, the rubber bag concept sounds interesting, I'll check it out.
As for my metaphor - actually I think it holds very true to what you're saying. You pre-qualified that the fire be hot enough to overcome the dampness of the sticks. That's my exact point. Think of the water as insulin and the stick itself as the fat you want to burn. If you're consistently slamming yourself into insulin shock then you'll never burn fat, and you'll end up looking like most of America(Myself included).
It takes very little insulin response to put our fire out.
No one is refuting thermodynamics here - simply stating that making the assumption that the body is a perfect machine (Or set at some guaranteed rate of efficiency) is a flawed outlook.
Taubes makes a great case for this in his examination of Native American Women and their children.
Now you're using the body's metabolism to explain the metaphor to explain the body's metabolism. I don't think it's supposed to work that way. :) To highlight some of the difficulties:
So, insulin shock is the specific heat of water and/or the heat of evaporation? Does fire "slam into" the water?
As a technical point, there's a distinction between heat and temperature. The fire does not need to be "hot", it just needs to have enough heat to evaporate some of the water on the new wood, and of course hot enough to catch the wood on fire. At that point the reaction becomes self-sustaining.
I don't know how to apply that heat/temperature distinction to the metaphor.
If the "fire is out" then what are we using to survive?
(These are rhetorical. I think I know the point you're trying to get across.)
Also, what does a "perfect machine" have to do with anything? Surely not from a thermodynamics viewpoints. I can't think of anyone who thinks of the human body as a perfect machine, and I have a hard time thinking of what that would even mean.
While I'm amused (Really I am, no sarcasm!) with the extension of the fire concept - I think you're just pulling at semantics of my metaphor =)
You make a valid point - lets pull heat and temperature out of it. I'll take the whole metaphor out. If I were to waterdown the through process of ketogenic diets (which are what I'm talking about and share some things with Paleo) I would explain them as such:
Insulin prevents your body from breaking down it's natural stores of energy. When you eat anything with a high glycemic index (Which is most food in the American diet) you have an insulin reaction. While having an insulin reaction, you don't burn fat stores. If you can't burn your fat stores, you don't lose weight. If you can't burn your fat stores and you run out of immediately available energy your bodies 'fire' dims (You crash after that sugar rush)
Ketogenic diets are the only diets that make sense to me, because they so easily explain the different states of weight gain/loss and energy level. I'm interested in hearing other methods of weight management.. but I really feel the ketogenic concept explains the body best.
> Sugar does not cause hyperactivity in children. Double-blind trials have shown no difference in behavior between children given sugar-full or sugar-free diets, even in studies specifically looking at children with attention-deficit/hyperactivity disorder or those considered sensitive to sugar.
> At least 12 double blind randomised controlled trials have examined how children react to diets containing different levels of sugar.2 None of these studies, not even studies looking specifically at children with attention-deficit/hyperactivity disorder, could detect any differences in behaviour between the children who had sugar and those who did not.3 This includes sugar from sweets, chocolate, and natural sources. Even in studies of those who were considered “sensitive” to sugar, children did not behave differently after eating sugar full or sugar-free diets.3
> Scientists have even studied how parents react to the sugar myth. When parents think their children have been given a drink containing sugar (even if it is really sugar-free), they rate their children’s behaviour as more hyperactive...
If a hypothesis depends on a mechanism we haven't observed, then I don't think it's likely to be real.
I've seen some work contradicting him, but would be interested in seeing something refuting him.
Your phrase "Compelling anecdotal evidence is an oxymoron" seems strange. If 5 people told me they saw my wallet outside, I'd be compelled to check, by anecdote, if I'd dropped it on my way in.
If the body digested everything with 100% efficiency and didn't produce waste, and also treated all 'calories' equally, then I'd agree that thermodynamics tells us everything we need to know.
But even people coming from the complete opposite end of the argument to the paleo crowd ("Eat more whole grains!") agree that the amount of heat produced by a substance when it's burnt in a calorimeter doesn't tell the full story about its potential for causing obesity.
I have no idea how cavemen lived, and it doesn't interest me all that much either, but my guess is that they weren't as sedentary and they weren't as proficient in the art of preserving food. Overall, it should have been quite difficult for most of them to create a caloric surplus, day after day.
What I do know is that bodymass is lost and gained with deficits and surpluses of calories.
Transient spikes in insulin and stuff like that are irrelevant. This is well established in nutritional science.
There's quite a lot of research with gut bacteria now and the association with obesity. It's not as simple as caloric intake, it is also the balance of the gut bacteria.
The Venus of Willendorf Is widely regarded to represent an exceptional, ideal image not a typical person. People who are short of food idealise a food surplus.
> The nickname, urging a comparison to the classical image of "Venus," is now controversial. According to Christopher Witcombe, "the ironic identification of these figurines as 'Venus' pleasantly satisfied certain assumptions at the time about the primitive, about women, and about taste." Catherine McCoid and LeRoy McDermott hypothesize that the figurines may have been created as self-portraits.
But let's face it, the evidence must be scant either way.
Still, if people from traditional societies enter the western world they tend to be afflicted even worse from civilization diseases (obesity, diabetes, strokes, heart attacks...). I think part of the problem is that our foods are engineered to trick the regulation of our food intake. Jared Diamond describes how New Guineans empty whole bottles of salt on their food, because they are much more "optimized" for craving salt.
So the energy in/energy out thing might hold, but it is just part of the problem. The real problem is how to regulate food intake appropriately.
Actually Dimaond also describes traditional people overeating to the extreme when they have meat on rare occasions (some kind of meat festival). So of course abundance of food is part of the problem - if those people had meat all the time, perhaps they would overeat immediately. But so we could still learn about sane frequencies of food intake from traditional societies.
Obesity is the result of a caloric surplus. Cavemen didn't have that luxury.