2011-04-13 19:54:36
During the winter, everyone will have gained a few extra kilos that they now intend to lose. But if gaining kilos is a matter of days, losing them can be a matter of months, years, … or a lifetime. For this reason, I thought it was good to tell you about some research that points to the possibility that, in the future, we can burn fat without leaving the couch, while we have an ice cream to cool off, although it may not be the healthiest.
As the weight-conscious reader knows, there are two types of fat, that is, two types of adipose tissue: white fat and brown fat. White fat (bacon) is what generates the dreaded love handles, since it is responsible for storing lipids from the calories that we eat in excess. Brown fat does not cause love handles because, unlike white fat, it is responsible for burning lipids to produce heat and thus maintain body temperature. Brown fat is essential, for example, to generate heat in newborns who, even if they are born in summer, go out into a cold and inhospitable world, compared to the mother’s womb.
Human beings have a lot of white fat which, in general, increases with age. Fortunately, we also have brown fat, but, unfortunately, the opposite happens with this than with white fat and its proportion decreases with age. Probably for this reason, older people tend to be colder than younger people.
Hormones and appetite
The amount of white fat we have depends on our appetite. If we have too much appetite, excess calories are transformed into lipids that are stored in white adipose tissue. It is well known that appetite is regulated by the action of several hormones. One of them, perhaps not well known to the general public (in all the meanings of the term “great”), is the so-called ghrelin. Ghrelin is a hormone produced by the stomach and pancreas that stimulates appetite. Other hormones, such as leptin, produced by white fat, decrease appetite, which is logical because if we have a lot of white fat, it is normal to stop eating and not store more calories.
Whether we gain weight or not depends, therefore, on a correct balance between the calories that enter and those that leave, that is, between those we eat and those we consume in exercise or daily activity. If this balance is not achieved, we either gain or lose weight. This correct balance also depends on the mechanisms that respond to the appetite-regulating hormones, in particular, on the proteins present in the cell membrane that detect them and launch mechanisms of action in response to that hormonal signal: the hormonal receptors.
To study how ghrelin and its receptor protein regulate appetite, a group of researchers at the University of Houston School of Medicine has generated mice through genetic manipulation that lack the gene for the hormone ghrelin, so they cannot produce it, well of the gene for the receptor of said hormone, so they cannot respond to its presence. The study of these mice did not give the expected results, since the mice without ghrelin or without its receptor ate and spent calories the same as normal mice, that is, surprisingly, they did not show a disorder in their appetite. However, the researchers found that mice lacking the ghrelin receptor did not gain weight with age, while those unable to produce this hormone, as well as normal mice, continued to gain weight as they aged.
Drugs and heat
The researchers also found that mice that could not produce ghrelin were colder and had more difficulty maintaining an adequate body temperature. However, the mice that did not have the receptor for this hormone were not cold. Why?
Since brown fat is responsible for generating heat to maintain an adequate body temperature, the researchers studied the properties of the brown fat possessed by mice without the ghrelin receptor and verified that these mice had more active brown fat, which It burned more fat and generated more heat than normal. However, it is a mystery why the same does not happen in mice that lack production of ghrelin, and not its receptor. Possibly, the ghrelin receptor also responds to the presence of another, as yet unknown, hormone that slows down the activity of brown fat, but this is, for the moment, just speculation.
Where do these studies lead us? Well, we can now think about developing a drug that binds to the ghrelin receptor and blocks its activity, which will activate brown fat. This will make us hotter, but also store fewer calories, which will be burned thanks to brown fat without the need to exercise more, even lying on a comfortable sofa.
However, there is still much to know about the mechanisms of appetite and metabolism control, so important for our health. In the meantime, the best thing we can do is take active care of our weight and take responsibility for ourselves. Perhaps it is not as difficult a task as it seems, if one insists on achieving it.
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