Monday, May 11, 2009

Overeating - Part 1

To a great degree, most of the adaptations that occur with dieting reverse when you overeat. Actually, that depends a lot on the situation. As I mentioned before, the body as a whole tends to defend against underfeeding better than it does against overfeeding which is why it's generally easier to gain weight than to lose it. Studies where leptin has been increased above normal (i.e. to try and cause weight loss in overweight individuals) have generally borne this out: except at massive doses, raising leptin above normal does very little.

There are a couple of theories as to why this might be the case. One theory is that normal
leptin levels send essentially a 100% signal, that is they tell the body that all systems are normal. It should seem clear that raising leptin above 100% isn't going to do much. Another possibility is related to something I alluded to above: leptin sensitivity and resistance. It's thought that people have varying degrees of leptin resistance which means, in essence, that they don't respond as well to leptin as they should. On top of this, when leptin levels go up, then it appears to stimulate resistance to itself. That is, when leptin gets and stays high, it causes you to become resistant to its effects.

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