Posts Tagged ‘insulin resistance’

Obesity starts in the brain


Where does obesity begin?  What drives you to eat too much or expend too little energy, and why has there been such a dramatic increase in obesity since 1980? Some recently popular explanations are the carbohydrate / insulin hypothesis (CIH), singling out the prevalence of carbohydrates in the diet, and the food reward hypothesis (FRH), putting the primary blame on the availability of “hyper-palatable” food.

In this post I will present evidence for new paradigm, which I call the  Hypothalamic Hypothesis (HH).  I think it provides a better explanation for the facts of obesity than the CIH and FRH theories, and leads to some different advice about how best to lose weight.

Some recent research suggests that obesity starts with specific physical changes to the brain. Appetite is regulated by the hypothalamus, particularly the arcuate nucleus (ARC), ventromedial hypothalamus (VMH) and lateral hypothalamus (LH). It turns out that two very specific changes to the brain cause us to get get hungry, overeat, burn less fat, and gain weight. And these changes to particular brain structures come about as a result of what you eat, eating frequency, and to some extent your activity level. The problem of obesity or overweight is often portrayed as a single problem, but it is really two problems, and each type of obesity corresponds to one type of brain alteration. Failure to distinguish these two types of obesity has resulted in much confusion. In part, the confusion comes about because these two types of obesity frequently occur together in the same individual, although one type is usually dominant. If you understand this, and you understand the role your brain plays, you can become more successful at losing excess weight.

I’ll spend a little time explaining the theory, provide some specific suggestions for how it can help you fine tune your weight loss program, and try to point out why I think the Hypothalamic Hypothesis overcomes some weaknesses of the other obesity theories.

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Does tasty food make us fat?

Are we getting fatter because there is just a lot more irresistibly delicious food around us?  Does that explain the obesity crisis?

That theory has been around the block but it is in fashion again.   In 2009, David Kessler’s book, “The End of Overeating” put forward the thesis that food in contemporary American food has been deliberately engineered–by adding fat, sugar and salt–to exploit our neurochemistry and hijack our free will.

More recently, one of the luminaries of the Paleo movement, Stephan Guyenet, has formulated his own version of this theory, in a compelling series on his Whole Health Source blog, arguing that  “food reward” is a main driver of obesity. His prescription:  eat a bland diet. Guyenet’s talk about this at the Ancestral Health Symposium last month is the buzz of the paleosphere.

But I think the theory is wrong, for the simple reason that it too blindly takes correlation for causation. And in doing so, it gets the causal direction mostly wrong. We don’t get fat because food has become too tasty. Rather, to a large extent, it is the metabolism and dietary habits of the obese that make food taste too good to resist, leading to insatiable appetites. And the good news is that we are not consigned to blandness.  If we eat and exercise sensibly, we can eat flavorful, delicious foods and enjoy life, without packing on the pounds.

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Does insulin make you fat?

Posted 03 Feb 2011 — by Todd
Category 亚搏体育客户端下载

Whether or not insulin is to blame for the obesity epidemic is one of the hot questions being debated on heath and diet blogs.  On the surface, this seems like an arcane question that would mainly interest physiologists and diet researchers.  After all, who really cares about the underlying mechanisms of fat storage and release?   Most of us just want to know some practical steps we can take to lose excess weight and keep it off and, beyond that, to stay healthy.

It seems like a simple yes-or-no question of fact that you could settle by studying populations and doing lab studies. But it’s not so much a question about facts as one about causation.  Questions of causation are often the thorniest ones. This particular question has taken on almost political or religious overtones, provoking emotion and acrimony in the diet blogosphere. On one side are defenders of the Carbohydrate/Insulin Hypothesis, like Gary Taubes and Michael Eades.  This is laid out in detail in Taubes’ book  Good Calories, Bad Calories (2007), and more compactly in “Why We Get Fat: And What To Do About It” (2010). On the other side are opponents such as James Krieger and CarbSane, who find the Carbohydrate/Insulin Hypothesis to be oversimplified and deeply flawed, citing recent scientific advances. People tend to chose up sides in this debate.  I’ve been participating in this debate myself (while still learning a lot) on the websites of Jimmy MooreJames Krieger, and CarbSane. I won’t rehash all the technical details here. Instead, I’d like to propose a “frameshift” that recognizes and integrates the strong points from each side, attempting to overcome their shortcomings.

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