Posted by larryhoover on December 25, 2012, at 15:06:58
In reply to Re: High fat diet -) inflammation -) depression, posted by larryhoover on December 25, 2012, at 13:27:49
It worked. Merry Christmas!
I've been following the nutritional science that I think relates to the obesity epidemic, the prevalence of depression, diseases of Western civilization (obesity, type 2 diabetes, heart disease, hypertension, dementia, stroke, and so on) for a while now. And quite frankly, the evidence contradicts the most basic tenets of the dogma of the day. Chronic ingestion of carbs is the root of all these evils, not fat intake. After all, if you want to fatten an animal, you feed it on grains, not fat. Why would we be any different? Let's see if I can at least raise some curiosity about my own belief.
My intellectual journey started with the reading of this article, by Gary Taubes. It's called "What if it's all been a big fat lie?", which was published in the New York Times. Here's the link:
http://www.nytimes.com/2002/07/07/magazine/what-if-it-s-all-been-a-big-fat-lie.html?pagewanted=all&src=pmThat got me thinking, especially the part about the historically accepted common wisdom always having been that starches and sugars made you fat, until that idea was challenged by an hypothesis put forward by a doctor named Ancel Keys, which blamed obesity on fat intake. Somehow, this theory becaome "fact" (more properly, a factoid), and the brain-washing began. That's a strong term, brain-washing, but it is a reasonable term when one considers that we are taught to believe something that runs contrary to most of the available evidence. How is it that the obesity epidemic is worse over time, as we collectively cut fat intake? How is it that obesity is far more common in lower socio-economic circumstances?
To get to the heart of the problem, you have to understand that insulin does a heck of a lot more than simply regulate sugar metabolism. It controls fat metabolism, too. It also controls appetite, although indirectly.
Sugar is toxic. Just consider what happens to uncontrolled blood sugar in diabetics. It can kill. Even in well-controlled diabetics, blood circulation is adversely affected, especially in the periphery. Nerve damage is common, and cumulative. But diabetes is often comorbid with hypertension, cardiovascular disease, obesity, and high blood lipids. Seems like that Western civilization disease list, actually.
Sugar consumption is also very strongly correlated with major depression, on a population-wide basis. Link: http://www.ncbi.nlm.nih.gov/pubmed/12415536
Just as an aside, I think that sugar in this case could be a surrogate marker for other intances of food processing, which would artificially inflate the correlation coefficient. Americans now consume over five times the amount of sugar than they did a century ago, so maybe there's a link to mental health issues today. And if you follow the rest of what I bring forward, maybe you'll see the connection.Getting back to Taubes, he got me looking at the Atkins diet, which is prominently discussed in that article that I led off with. Atkins does not rely on calorie restriction. You eat until you're satisfied. And yet, you lose weight. But Atkins has been attacked for decades, as the primary source of energy is from fat. And fat is no good for you, right?
Let's look at a modern comparison of the Atkins (very low-carb), Zone (low-carb), Ornish (very high carb), and LEARN (low-fat, high-carb, calorie restricted) diets. Participants were obese and overweight premenopausal women. The study was conducted over a 12 month period. http://jama.jamanetwork.com/article.aspx?articleid=205916
In all variables in which there was a significant difference in outcomes, the Atkins diet was the best. In fact, Atkins participants lost more weight, lowered their blood pressure more (especially systolic), had greater increases in HDL (good cholesterol), and greater reduction in triglycerides.
What's that, the highest fat diet had lower circulating blood fat levels, and greatest reduction in cardiovascular risk factors? Yes.
How is that possible? Insulin.
As we know, insulin regulates sugar metabolism. But sugar metabolism is not our default source of energy. Fat is the "normal" energy source for all cells, directly or indirectly. It is only in the presence of dietary sugars (including starch) that insulin is secreted by the pancreas in substantial amounts. Insulin tells all cells to shut down their fat metabolism, and switch over to burning sugar, to keep it from reaching dangerous levels in the blood.
Perhaps the most profound change arises in two separate tissues, the liver, and adipocytes. Adipocytes are fat storage cells, most commonly found in the hips, buttocks, and abdomen. When the body is in fat burning mode, adipocytes buffer the fat content of the blood, by absorbing and releasing fat as needed. But, in the presence of strong insulin levels, adipocytes stop releasing fat. They can only take it up, i.e. store it. Moreover, the insulin commands both the liver and adipocytes to manufacture fat out of sugar (a process called de novo lipogenesis). The effect is to partition energy into storage, rather than using it to supply the body with energy. Only when the insulin level falls back towards baseline can the adipocytes begin to release fat once more.
But something else happens in the adipocytes, as well. Adipocytes are actually part of the endocrine gland system, releasing regulatory hormones. As insulin falls in the blood (i.e. sugar is depleted to safe levels), the adipocytes release appetitive hormones. You get hungry. So, in the face of recurrent carb intake, your adipocytes continue to do what they were programmed to do. They store fat, and make you hungry. So long as carbs are available, you will be hungry enough to eat more, and store more fat.
And now we come to the issue of cause and effect. We all know that obesity is associated with over-eating, and low physical activity. We are told that obesity is caused by over-eating and low physical activity. In fact, it's the other way around. Obesity causes over-eating, and low energy levels.
My assertion is based on a better understanding of the interplay between insulin and energy metabolism as a whole. Insulin only comes into the picture in a meaningful way when sugars are flooding the bloodstream. Insulin shuts down fat metabolism altogether, and partitions a significant proportion of the ingested carbohydrate calories into fat. The result is that even in the presence of abundant energy sources, the body is actually starved of energy, once the sugars are depleted from the blood. It takes time to turn on the fat metabolism once more, and in the meantime, your energy level plummets. But before the energy flow can be restored, hormones make you hungry once more. Rinse and repeat.
Our bodies are not capable of maintaining this carb-driven cycle for extended periods of time, without having other regulatory systems upregulated, to try and force things back into the normal range. Inflammatory cytokines are released in increasing amounts, in an attempt to force cells into ignoring the effect of insulin. Appetitive hormones (especially leptin and ghrelin) compete for dominance, often resulting in leptin resistance (very common in type 2 diabetes).
Meanwhile, what about dietary fat? Remember the Atkins study, which showed that triglycerides fell on a high-fat diet? Here are a couple of full-text articles to cover those issues. Basically, dietary saturated fat is independent of blood levels of saturated fat, strange as that may sound.
http://www.njmonline.nl/getpdf.php?id=10000756
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974193/Sorry, I've got to run to get to Xmas dinner! I'll close with an abstract that indicates that some scientists are indeed questioning the dogma of today.
http://www.metabolismjournal.com/article/S0026-0495(12)00438-6/abstractGary Taubes has written a very accessible book, called "Why We Get Fat: And what to do about it." He covers a lot of this stuff in fascinating detail, including the history of each nutritional myth.
More, anon.
Merry Christmas,
Lar
poster:larryhoover
thread:1033371
URL: http://www.dr-bob.org/babble/20121217/msgs/1033789.html