Saturday, October 10, 2009

7. The Body Grows Larger

Ironically, the arguments made above suggest that aerobic exercise is ill-advised for those who suffer from this impaired glucose-uptake syndrome. While many have speculated that our more sedentary lifestyle is likely a contributing factor toward obesity, I believe that instead physical fatigue itself is a predictable outcome of defective glucose metabolism, The inability to obtain sufficient fuel from glucose on the part of both the muscles and the heart simply saps us of the energy to move around [22] (Details) .

The effect of sustained aerobic exercise is to switch the muscle back into a glucose-uptake modus operandi for energy acquisition, which, however, is malfunctioning due to calcium and insulin insufficiency. Exercise is able to induce GLUT4 to migrate to the membrane even in the absence of calcium [13] . The insulin/glucose levels fall to possibly dangerously low values, which induces the appetite center in the hypothalamus to sound the alarm bells. The subsequent appetite stimulation induced by AMPK in the hypothalamus overrules all of the other appetite regulating signals and compels the person to overeat the very foods they should be avoiding.

As a consequence of further increases in the already high levels of sugar in the blood, the fat cells are compelled to squirrel away as much of the excess sugar as they can. Particularly susceptible to this urge to make fats will be the abdominal fat, since it is situated in close proximity to both the pancreas and the liver. The higher blood concentrations of both insulin and glucose provide extra impetus to assimilate sugars and manufacture fats. Thus the abdominal fat cells are more efficient in storing food than the peripheral fat cells. They will also tend over time to increase in size and multiply, in order to distribute the task load among their neighbors and reduce the burden carried by each individual cell. The additional fat cells will further deplete the available calcium and vitamin D in the blood, leading to an even poorer ability on the part of the muscle cells to take up glucose.

Alongside the growth of fat cells, other cell types also need to become more abundant, to support the increased burden of a larger body size, combined with reduced energy supply. As already mentioned, the heart becomes enlarged. Muscles must increase in size both to be able to haul around the extra weight and because of their innate inefficiencies in fuel utilization [14]. Bones must grow bigger and stronger to support the excess weight. Blood supplies have to be extended to supply nutrients to all of these proliferating cells. All of this means that the body's overall nutritional needs continue to grow, which puts futher burdens on the fat cells, thus completing the vicious cycle. Over time the person with a severe deficiency in calcium, vitamin D, and fats grows steadily larger, eventually reaching a condition of morbid obesity.

No comments: