Monday, July 12, 2010

Are We Programmed Inside the Womb?

By Christian Wernstedt

Loren Cordain recently linked to this paper which adds to the evidence that we are significantly affected in adulthood by the diet and metabolic condition of our mothers during pregnancy.

In this case, the paper shows a correlation between excess protein intake in pregnant women and elevated cortisol (a stress hormone) in their offspring as adults.

The findings are correlations, but there is a straightforward theory of causation which is that if the developing fetus is exposed to high cortisol concentrations (as occur after the mother consumes a big protein meal) its cortisol-setpoint may be affected to program lifelong hyper-secretion of cortisol, potentially leading to disease later in life.

If this hypothesis is true about cortisol, then very likely other hormonal setpoints are affected as well during gestation, explaining some of the differences we see in people's ability to handle excess calories, carbohydrates, stress, etc, as well as how easy it is to correct health problems related to such metabolic- and hormonal issues.

(The environment that we are exposed to during childhood is of course also important.)

Now, to a somewhat philosophical question: If there is such a thing as a "setpoint", where is it located, and can it be changed once programmed in the womb?

I tend to think that physiological setpoints are not like the programmed setting on a mechanical thermostat, or the contents of a computer's ROM (read only memory), but should rather be viewed as regulatory equilibriums that are emergent phenomena. That is, setpoints don't exist as physical entities, but are rather an effect of physiological processes aiming for homeostasis in each transition from one state to another. (The whole chain of transitions beginning at conception - or earlier if we want to be precise.)

It may be difficult to change these equilibria because of the negative feedback loops involved in homeostasis. For example, if we try to affect our fat set points by diligent fasting, the body may respond by making us hungrier and up-regulate fat storage.

On the other hand, I don't think that we should throw in the towel on affecting our setpoints.

If setpoints are indeed expressions of equilibria let's, for instance, learn how to push the underlying hormonal- and biochemical processes in a desired direction without triggering negative feedback such that a reorientation around a new equilibrium (setpoint) is achieved.

I think that this can be done at least with some setpoints. For instance Martin Berkhan at Leangains seems to have found a program for getting quite obese people down to single digit fat percentages and to keep them there. Perhaps this involves re-setting the set point of leptin (a hormone regulating our fat stores).

Another way to handle one's setpoints is of course to acknowledge them and adjust our lifestyles to make the best possible out of our individual configurations.

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