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jueves, 21 de noviembre de 2013

Hereditary childhood obesity

Some time ago I received a question from a reader worried about if his obesity would be inherited by his son soon to be born. I mean, he worried if obesity was "written" somewhere in DNA.
I must mention that this is a controversial issue and is not in any way closed. Some scientists dismiss saying that it is the environment that determines the possible child obesity while others argue the genetics as the main responsible for obesity .
We have all observed that children born from obese families tend to be obese. We have also assumed that unhealthy eating behaviors of parents were being acquired by their children and that was the reason for childhood obesity. And often we not have believed those individuals who say they eat very little but they are fa , assuming also they do not tell us the truth . At the same time we noticed that there are people eating out of control and yet maintain normal weight or even lower than they should .
For some time now these two paradoxes tried to be explained by the  called  Set Point Theory  (Keesey , 1980 ) . This theory says that the human body acts about weight the same way you it does  with the body temperature or blood pressure : there is a balance that is recovered when a decompensation happens . If our body temperature drops , the body reacts to regain normal temperature. Well, so does with our weight : if you try to lower the weight the body reacts by trying to regain the weight that it is "considers appropriate " . The balance point varies with intake of calories , so when we try to lose weight our body tries to regain the weight that is "normal " accordign our calory intake and is in a very high level for those who have been obese . That would explain the rebound effect of aggressive diets and why some people find so difficult to lose weight.
Why this balance varies ? Why is not maintained at a fixed value such as with body temperature, for example? The answer is that it depends on two key factors : the number of fat cells and metabolic rate.
Adipocytes are cells whose main mission is to store fat which is then used to generate the energy that our body needs . Adipocytes are the main culprits of obesity. Adults have a fixed amount of adipocytes. If we get fatter the adipocytes get bigger but do not vary in number . Instead children are known to CREATE ADIPOCYTES to store the extra fat that goes into their bodies. It follows that if the child is above their recommended weight ,  it's for sure they have a number "extra" adipocytes which will no longer leave them for the rest of their life. Let's say they are  marked for life with a tendency to be overweight .
Metabolic rate  is the minimum amount of energy that the cell needs to survive. To put it simply, is the ability of our body to burn more or less quickly the calories we consume . Not everyone burn calories in the same manner . Same wieght and  age a man has a higher basal metabolism than a woman . After age 40 basal metabolism slows down and some people tend to put on weight .
Cells need energy even if we are sedentary state . Ideally you would be able to burn the whole extra intake of calories that you get, but in exceptional cases, does not usually happen . To speed up the process there are several methods. The most effective is exercise, while other "tricks " can be drinking lots of water , sleep little warm , eat many times a day but so sparingly . In any case it is clear that two individuals will never have identical metabolisms unless genetically identical.
We are all born with the same adipocytes but our basal metabolism is different but we can not do anything about it . This indicates that the different way to burn calories between people must have a genetic reason like lifestyle , age , sex etc. .. Well, some research suggests that obesity is inherited through mitochondrial DNA .
Mitochondrial DNA is the genetic material of the mitochondria , the organelles that generate energy for the cell. Depending on the genetic load is determined the individual's ability to burn calories at a cellular level . A smaller inheritance of mitochondrial DNA , the lower the ability to burn fat. Mitochondrial DNA is received only from the mother, which is not to say that is only up to the mother if our child is obese or not. There are many factors that can influence but mitochondrial DNA is probably one of the most important.
So imagine two parents or maybe only one of them , with obesity problems , with many adipocytes and a lower metabolic rate . This does not mean that our son will or ought to have obesity problems. We can do something to avoid such situation.
First we watch the diet to avoid childhood generate extra adypocites. This is achieved by keeping their weight within the appropriate percentile through  healthy, low -fat diet . We need to give to the kids the exact rations and never extra feed. I understand that many parents see how their  baby happily takes bottle after bottle, but that's not the best if we suspect about hereditary obesity . If we get that in childhood the child is kept in a good weight and he/she DOES NOT GENERATE  EXTRA ADIPOCYTES IT WILL BE MORE DIFFICULT TO  HAVE OBESITY WHEN ADULT. And of course we must accelerate his/her metabolic rate. As soon as possible we will forbid sedentary habits and try to force him/her to play sport at school or simply go walking to school instead of taking the bus or use the car.
But above all it is important not to make the child object of our obsession with being overweight : simple and continuous actions are more effective than criminalize him/her by eating some candy ocasionally.

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