aprilynnd wrote:There are many terms for metabolic damage (MD) - metabolic adaption is favored in the literature - but I'd like to clarify what I mean by metabolic damage. I'm defining MD as a down regulation of energy use/expenditure due to inadequate calorie consumption that persists beyond the restriction period.
How far beyond the restriction period?
The longer you stretch it, the less credible it becomes.
Humans are highly adaptive. If it were beneficial to have a low metabolism, we would just have low metabolisms, period. It's beneficial for our metabolisms to suit our behaviors and diets, and the faster that adjustment happens, the more evolutionarily advantageous it is -- to a limit. The only exception being brief forays which have a low probability of indicating an actual change in circumstance has occurred.
Such responses are pretty easily explained or understood by alteration of programmed cell behavior by circulating chemical signals.
aprilynnd wrote:brimstoneSalad wrote:
There may be some moderate epigenetic contributions to metabolic rate, but "metabolic damage" as it's presented is a fabrication. Epigenetics are hard to change, and you may have even inherited them from your prenatal days. That doesn't change the fact of calories in and calories out.
I take issue with the comment that "epigenetics are hard to change". Epigenetic is a field of study focusing on how gene expression can be modified by environmental factors.
Technically gene expression could be said to be altered by hormones too, but we don't broadly consider that 'epigenetic': at that point, you could throw almost anything into the epigenetic sack. How about a suntan? Gene expression for melanin production is stronger due to UV exposure? Anything and everything a cell does in terms of changing behavior could be argued to be varying gene expression in some sense.
You're expanding the term to account for things far beyond the well accepted range. I fear it has become a popular buzz word like quantum or nano, and that's a red flag for pseudoscience. It creates a plausible sounding explanation which makes people think what you're saying is sciencey, but without evidence, that's all it is: plausible
sounding.
I'm just going to quote Wikipedia and leave it at that: if you disagree, let's chalk it up to semantics (but I think you're using the term too broadly, and if I saw claims like you're making on a website alarm bells would be ringing telling me to beware of pseudoscience)
https://en.wikipedia.org/wiki/Epigenetics
In the science of genetics, epigenetics is the study of cellular and physiological phenotypic trait variations that result from external or environmental factors that switch genes on and off and affect how cells express genes.[1][2] Hence, epigenetic research seeks to describe dynamic alterations in the transcriptional potential of a cell. These alterations may or may not be heritable, although the use of the term epigenetic to describe processes that are not heritable is controversial.[3] Unlike genetics based on changes to the DNA sequence (the genotype), the changes in gene expression or cellular phenotype of epigenetics have other causes, thus use of the prefix epi- (Greek: επί- over, outside of, around).[4][5]
aprilynnd wrote:Dr. Campbell (and associates) was able to affect cancer development (gene expression) in the course of research studies by modifying protein intake.
Was it heritable to the cell line's descendants? Did he modify it for a few days, then return it to normal, and the cancer kept withering away due to epigenetic metabolic damage?
As I understand it, cancer springs right back into action as soon as you change the environment. It's basically a lack of food, so it doesn't grow as fast. Everything is arguably gene expression. Be wary of the science-sounding buzzwords. Nothing in that example is relevant to the so called "metabolic damage" I was criticizing.
aprilynnd wrote:I haven't learned much about the link between metabolic adaptation and epigenetic changes so I'd be interested in any references you may have.
I haven't learned very much about the Reptilian overlords who control the world government either.
Sometimes there's a paucity of credible information about something because it's a myth. I'm not out to prove a negative here.
If there were legitimate evidence of epigenetic metabolic adaptation, I'd be all over that. But again, credibly referenced, such adaptations usually refer to heritable changes -- long term, across many generations. Other uses of the word would be dubious. It's those changes I mentioned as difficult to affect. They're usually things that become "hardware", and can't be changed quickly due to major physiological differences, like cellular differentiation.
aprilynnd wrote:However, we do know metabolic adaptation occurs quickly - we learned in school that a 15% reduction can be seen within 2 weeks of a calorie restricted diet.
Right. Not epigenetic proper. And it's fast, like I said. It's probably all based on circulating hormones. Long term metabolic damage is a myth. It's evolutionarily prudent to adapt quickly to the environment, and there are no structural issues getting in the way of that.
aprilynnd wrote:If indeed epigenetic changes are hard to produce, they are likely not involved in down regulation of metabolism. (I'm apologize for not having a reference for that - I resold the textbook).
There may be some limited evidence of actual epigenetic factors that are multi-generational. This is a matter of ongoing research. You might as well call them genetic as far you have any control over them. These are extensive cellular and structural differences. Your behavior and fitness could affect your children. And they're mostly stuck with it as you are with the choices your mother made before you were born.
The future of your children is a good reason to get fit, perhaps, but aside from that it's not a meaningful health message for most people because it's just depressing to think you're screwed (or at least unfairly disadvantaged) because your parents were fat and lazy.
aprilynnd wrote:This is the main part that I really disagree with. I have personally experienced the exact phenomenon described by Freelee - long before I was ever vegan (I was eating Paleo actually) - but I won't rely on an anecdote to prove my point.
OK, well, you understand that's not evidence...
aprilynnd wrote:There is evidence that RMR can be down regulated in the long term. A study titled Persistent Metabolic Adapation 6 Years After "The Biggest Loser" Competition (1) found that 6 years after the competition contestants RMR was ~500kcal less than anticipated.
Let's look at that study:
http://onlinelibrary.wiley.com/doi/10.1002/oby.21538/full
Obviously a study with 14 participants is already a little weak, but with those margins of errors and confounding variables, this is ridiculous.
This is a pretty good criticism:
http://www.leighpeele.com/a-response-to-the-ny-times-biggest-loser-study
Before the show measurements:
Returning to the study, we see energy assessments taken during a time of rest and weight stabilization before the show. It’s even possible before the show a “stuffing of the pot” occurred with some of the contestants. Contestants have admitted to drinking excessive water and eating more before the contest and then dehydrating aggressively afterward.
That's a huge confounding variable which would make their normal RMR appear much higher, when genetically (or even due to actual epigenetics) these participants had a naturally lower RMR.
In terms of the followup, I also noticed this by just looking at figure 1:
Were They Weight Stable At Time of Follow-Up Readings?
Readings in the study were showing the subjects were not weight stable at the time of their final RMR readings. Activity expenditure was up and intake down. Were they doing this to look better for the study? To save face? Did they simply think they should? It wasn’t controlled.
You can clearly see a downward trend in figure 1, and they seem to be exhibiting abnormal behavior: mere awareness of their weights and caloric intake could do this.
The bottom line is that not only was this a small study, the controls were terrible. There actually have been controlled studies on this issue and they have not shown such an effect. To prefer weak conclusions of a poorly done study with a small sample and few controls (and glaring confounding variables) to more credible studies to the effect of saying there's evidence for something is a bad case of cherry picking.
Do More Controlled Studies Show The Same?
I like studies that control for variables as any good research enthusiast should. This 2008 study [
http://ajcn.nutrition.org/content/88/4/906.full] shows the decrease in RMR was pretty insignificant but the decrease in daily energy expenditure was much more notable. In general, we see in research what slows down more is not resting metabolic rate (RMR), but our activity levels. Could those contestants have ramped up their activity at the time of testing? We don’t know. It wasn’t controlled. To me, while it is an interesting free-living experiment to chew on, it is not the smoking gun which says an RMR decrease is the reason we have a hard time keeping weight off once it is lost or losing it in the first place.
I would also echo the conclusions of that criticism:
5. Mindset Matters
Your expectation is crucial in the role of fat loss. More often than not fat loss is seen as no different than hoping to win the lottery – and it shouldn’t be. Fat loss should be a mostly predictable process when you understand what you’re putting in (be it food, drugs, or drink) and putting out. The rest is trying to adhere to the process long enough to get results, which is easier said than done. For most people the road to fat loss is going to be a long and patient travel. Barring rare circumstance and situations (like the Biggest Loser) we are not in a fat loss boot camp with every focus to our need. We are in the real world with work, kids, distraction, procrastination, and more emotions than we know how to handle.
If you don’t believe in the process or think the process is untrustworthy, you’re not going to commit. The process does work. You will not be broken by the end of it.
If we're going to make claims about "metabolic damage", we had better be damned sure of them. If there's even a chance it's wrong, we should shut up about it due to the harm incorrect information can have: these kinds of argument can scare people away from necessary weight loss and calorie restriction. If you're afraid of damaging your metabolism and getting fatter, you might just think that's an excuse to give up.
See my post here, where I debunk a similarly harmful myth:
http://philosophicalvegan.com/viewtopic.php?f=17&t=2238&p=23703#p23703
