Posts Tagged ‘appetite’

Obesity starts in the brain

Posted 25 Nov 2011 — by Todd
Category Diet, Health, Psychology

 

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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Change your receptors, change your set point

Posted 25 Oct 2010 — by Todd
Category Diet, Fitness, Hormesis

Why is it so hard to make permanent changes to your habits, your health, and your happiness?  Some of the most difficult struggles in life involve losing weight (and keeping it off), overcoming addictions, and recovering from depression. Many diets and therapies deliver great short term results, but the most common pattern appears to be relapse.  It often seems that you are destined to fulfill some biological program — that you are stuck with a high body weight set point or an addictive or depressive personality that cannot be escaped in the long run.

This pessimistic message is prevalent among those who have investigated the track records of the “helping” industries: the weight loss companies, the addiction recovery centers, and the various schools of psychology and psychiatry. Unlike the advocates, those who investigate them often find the results are less than what the practitioners might want you to believe.  In the arena of dieting and weight loss, books such as “The Dieter’s Dilemma” (Bennett and Gurin, 1982), and  “Rethinking Thin”  (Kolata, 2008) echo the original set point theory first propounded by Gordon C. Kennedy in the 1950s; they conclude that your body weight is largely predetermined by a biological set point that is handed to you at birth, plus or minus about ten pounds. I do agree that sustained weight loss cannot be achieved through sheer will power alone, or simply by using diet and exercise in order to create a calorie deficit. Yet, while there is some plausibility to the set point theory, I am convinced that it is wrong because it overlooks some important factors. I’ve already given some of my reasons for my disagreement with set point theory in other posts on this blog (Flavor control diets, How to break through a plateau). But in this post I’ll present some strong evidence for an alternative theory, based on the homeostatic regulation of cellular receptors for hormones and neurotransmitters. This is a variable set point theory which I call the receptor control theory. This theory proposes a mechanism that controls appetite and body weight, as well as regulating the balance of  energy and pleasure in your life. It provides practical tools to lose weight and keep it off, overcome addictions without relapse, and move out of depression into happiness.

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