Posts Tagged ‘Stephan Guyenet’

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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The case against antioxidants

Posted 13 Mar 2011 — by Todd
Category 亚搏体育客户端下载 , Health, yabo亚洲

Antioxidant supplements are probably ineffective.  They may even be hazardous to your health.

Many people take daily supplements that include antioxidants such as Vitamins A, C, and E; beta carotene, coenzyme Q10, and alpha lipoic acid. I used to be one of them, convinced of the theory that supplementation with antioxidants is an effective way to neutralize harmful free radicals.  These free radicals, also called ROS or “reactive oxygen species”, can cause oxidative damage to cells and organs, and have been implicated in the pathogenesis of degenerative diseases such as cancer, heart disease, and Alzheimer’ disease.

However, study after study not only fails to show a consistent benefit, but in many cases documents positive harm from taking antioxidants. While I continue to believe that antioxidant supplementation is helpful in certain isolated cases of acute infection, tissue damage, or a damaged or aged metabolism, for most of us antioxidants are probably worthless. In fact, antioxidant supplements can interfere with and weaken the body’s inherent ability to mount an effective defense against oxidative damage and its contribution toward degenerative diseases.

I’ve resisted this conclusion because I could not make sense of it.  That is…until I came across recent research into the biochemistry and genetic regulation of the antioxidant response element (ARE). Fortunately the ARE provides us with an in-built adaptive stress response that combats oxidative stress and inflammation The ARE makes the need for antioxidants in the diet unnecessary — other than to keep our food fresh. Surprisingly, antioxidant supplements can impair our adaptive stress response.  But there’s much we can do to strengthen this response. Read More