See? I Told You So!!
I've got to say, I about fell off my chair reading the following comment from Stephan Guyenet over at Whole Health Source blog as it flittered through my feed reader. In response to a comment by Thomas, basically asking if insulin surges or calories ultimately govern weight loss/gain, Stephan had this to say:
Yes, the excess calorie consumption is the key. Insulin spikes do not increase food intake unless they cause hypoglycemia. In fact, insulin is kind of like leptin's kid brother: it acts in the brain to constrain fat mass.
Also, insulin is co-secreted with amylin, which also constrains fat mass by increasing satiation and possibly leptin sensitivity.
All this postprandial insulin spikes = fat gain stuff is nonsense as far as I can tell. I still haven't seen a shred of convincing evidence to support it, and in fact, the evidence I've seen mostly supports the opposite hypothesis, that insulin spikes oppose fat gain. The idea that postprandial insulin causes fat gain is contradicted by the most basic empirical facts in both human and animal studies. As I said before, I don't know a single person who studies metabolism/endocrinology professionally who takes that idea seriously-- it is confined to the popular press and internet blogs/forums.
Been saying this and backing it up with citations galore for over a year now. I'm excited to see others finally setting the record straight publicly. First Stephan comes out as a not-so-closet potato eater. Now he's forthrightly rejected Taubes' insulin hypothesis. What next? Dancing with the Stars? Or perhaps the next institution of higher learning inclined to invite Gary Taubes to lecture their medical students might be better served inviting someone else.
There's at least one researcher ... I don't know if Lalonde has changed his mind, but in response to Jimmy's question, didn't Mat Lalonde try to dismiss James' myths series by claiming the experiments that showed insulin suppresses appetite were strictly "non-realistic direct brain injection studies" ?
Lalonde's false dichotomy (no room between non-physiological brain injections and insulin resistance):
Mat Lalonde, Harvard PhD research biochemist (courtesy of Robb Wolf)
Old school insulin research experiments involved injecting insulin into the brains of animals. They would inject one large dose of insulin and noticed that it made the animals stop eating. However, this is an acute response. Most hormones have acute and chronic responses. Acute exposure of the brain to insulin blunts hunger because it clears dopamine from the brain, which signals the end of a meal. The brain becomes insulin resistant upon chronic exposure to insulin. The chronically high levels of insulin that result interfere with the satiety hormone leptin, which makes the body think it is starving and causes the animal to eat more.
I suppose if he gets called on it he can claim he meant "acute" being a regular meal, although I canNOT see that interpretation: he wrote about "acute" and "injection" in almost the same breath.
Chronic infusion of insulin into primate brains causes fat loss and a reduction in food intake. Also, the brain-specific insulin receptor knockout mouse is overweight. Insulin acts chronically as well as acutely, and that seems to be true of amylin as well, which is co-secreted with insulin.
I have had a few friendly communications with Mat Lalonde. If I understand correctly, as of April he did not believe that carbohydrate per se or postprandial insulin spikes cause fat gain or metabolic syndrome.
Without intending any disrespect to Mat, I would also like to point out that he is not a metabolism/endocrinology researcher. Mat is a smart person who has learned a lot about metabolism/endocrinology/health through his own reading and experience, but his primary research is in chemistry last time I checked.
I saw no clear middle stance in what was reported, but I did want to clearly give him the benefit of the doubt.
High-fat feeding promotes obesity via insulin receptor/ PI3K-dependent inhibition of SF-1 VMH neurons
Klöckener, T et al.
Nature Neuroscience, June 2011
But maybe it's not what I think. Would anyone care to have a look?
Good luck with that if you can manage to stick to it.
By careful were you are going with this Stephan !
Last time I checked, Seth Roberts is certainly not a metabolism/endocrinology/health researcher.
In fact, whenever he gets the opportunity, he states that the only reason for him to have come to the Shangry La diet (flavor-calorie disassociation) is by being an outsider and that for insiders (you) it is nearly impossible to come up with these insights .
You are young in this field and you show great promise, so please do not end up as most of your fellow researchers hunting grants by ignoring the awkward (in other words, don't become part of the gatekeeper syndrome http://blog.sethroberts.net/category/gatekeeper-syndrome/. )
Seth Roberts is a PhD researcher in psychology, so he's hardly an outsider. His ideas draw heavily from the research of Anthony Sclafani and Michel Cabanac, who are about as insider as you can get-- career researchers who have been at it for decades.
Roberts doesn't address the carb/insulin hypothesis, or at least I don't recall him addressing it. He is not a metabolism/endocrinology researcher, and he never claimed to be an expert in that realm, which does not detract from his ideas because they aren't based in that field. The hypothesis that his book outlines lies squarely within his own scientific specialty.
I'm open to insights from anyone, no matter what their background is. But if you want bricks laid correctly, you're more likely to have it done right by a professional bricklayer who has been doing it every day for years and has hands-on experience. That doesn't mean the accountant next door isn't the best bricklayer in town, but it is less likely.
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