Obesity: a really fat health problem
2003/05/01 Galarraga Aiestaran, Ana - Elhuyar Zientzia Iturria: Elhuyar aldizkaria
Explaining how a person becomes obese is not difficult: he gets fat because he eats more than enough. The excessive calories you eat build up as fat in the body and eventually become obese. But it is not so simple to explain why this trend or behavior has spread throughout society.
Many factors influence the deployment of obesity. In developed countries, food industries offer, through giant advertising campaigns, foods of unquestionable appeal, which in most cases have a high caloric value and a low nutritional value. In addition, thanks to the car, television, telephone, computer and other technological advances, it is not necessary to move as much as before to make everyday life. Therefore, it is very easy to eat more calories than necessary. As a result, health care budgets increase the weight of obesity and associated chronic diseases.
In developing countries, the situation is no better. As the economic level increases they acquire the customs of the developed countries. Therefore, although part of the population has malnutrition problems, it is not uncommon that at low social levels there are also obese.
Saving gene
It is clear that the environment and lifestyle have a great influence on the deployment of obesity. However, according to some experts, there are also biological reasons that lead to eating more than enough.
Although in general there are more obese and obese than before, not everyone has fattened the same, even if it is in the same medium, but lately the proportion of obese has grown much more in some ethnic groups than in the rest of the population. According to this, within the human species there seem to be different groups, that is, they tend to become obese and are resistant.
Although the biological system that controls body weight is robust, the force of selection on it is very large and it is logical to think that the genes involved in it have varied depending on the environment.
James Neel was the first to propose it. In 1962 he launched the saving gene hypothesis. These genes facilitate the accumulation of fat, that is, reinforce the tendency to become obese. The presence of these genes was beneficial in times of food shortage, such as when people were hunter-gatherer, as there was always a risk of hunger. By allowing the sparing genes to have fat reserves, those who had them were more easily confronted with times of hunger.
For their part, those who lived in the Rich East had domesticated plants and animals and had not so much risk of hunger. The tendency to obesity in this area was not an advantage since obese people have more health problems. That is why they believe that, unlike other areas, there was a selection against saving genes.
Today, in Western society, most people have more food than they need; moreover, they have a sedentary life, that is, far from that of hunter-gatherers. However, the human species carries genes from selection in both areas. According to some experts, and simply put, the obese are descendants of hunter-gatherers, while the thin are descendants of the population of the Humpback East.
There are studies that reinforce this view. Studies of American Indian peppers, Pacific Islanders and other populations historically threatened with hunger have shown that the proportion of obese is much higher than in other populations.
The root of the problem is likely to be found in the interaction between genes and the environment, and both should be taken into account when understanding obesity and seeking solutions.
Weight regulation
The mechanisms involved in weight regulation are not well known. However, more and more research is underway and important steps have been taken in recent times.
Weight control systems are short-term and long-term and in recent years molecules have been found participating in one or the other. For example, recently two hormones produced in the digestive tract have been found: ghrelin and PYY peptides. Both participate in short-term regulation. Leptin and insulin are related to long-term regulation.
Precisely when leptin was discovered in 1994, researchers thought that effective treatment against obesity was possible. Cells that accumulate fat, adipocytes, produce leptin: by decreasing fat deposits, less leptin is produced, which causes appetite to be aroused and metabolism to slow down. During laboratory tests, obese mice treated with leptin lost appetite and accelerated metabolism. As a result, lose weight.
However, the dreams of the anti-virility pill were frustrated soon. Few humans do not produce leptin, which makes them obese. In these cases, leptin treatment is effective. In obese with normal levels of leptin, however, this treatment has no effect.
Although leptin has had a great impact, insulin has also taken a major role. It is not new that insulin has an effect on the brain related to weight regulation, but so far there have been no thorough studies. They have now seen that it reduces appetite, preventing the production of neuropeptide Y (NPY) that awakens appetite.
Appetite versus saturation
In short-term mechanisms, cholecystokinin has been identified for years. It occurs in the intestine and is called ‘saturation hormone’ because it warns that it has eaten enough. Researchers have now focused on PYY ghrelin and peptides.
Ghrelin was discovered a few years ago, it occurs in the stomach and causes the secretion of growth hormone. Later they discover that it has another effect: it is a powerful stimulus of appetite. This discovery solved many doubts until then.
In fact, researchers realized that the feeling of hunger always manifests itself at the same times, for example, around noon, and that was difficult due to leptin, as fat stores do not decrease from breakfast to noon.
Now they know that it is the work of the Sparrow. One or two hours before meal time, the degree of ghrelin increases and decreases after eating. Some cases of obesity are related to overproduction of ghrelin. On the other hand, in those who have lost weight through diet, they have observed an increase in the production of ghrelin, not in those who have undergone a stomach operation. This operation involves bonding the upper part of the stomach with the small intestine and is quite effective in treating extreme obesity. After this operation, ghrelin production does not increase and, to some extent, explains why they do not regain weight.
Researchers therefore know what causes appetite. And what does he say has eaten a lot? It seems that it is the PYY hormone that has that function. When eating, the PYY peptide increases its level and gives a signal of saturation in the brain. Recently, researchers have released research on melatonocurtain receptors. In addition to the skin color, it seems that they may be related to erection and weight loss.
Is it possible to control the weight by preventing the tail, raising the pyy level or acting on the receptors? The tests performed at the moment have not yielded good results. In addition, these hormones do not only affect the regulation of weight, for example the ghrelin has to do with growth hormone, and much remains to be investigated. But gradually researchers are discovering the keys to understanding the mechanisms of regulation.
Global concern
As research progresses, obesity is constantly expanding. The World Health Organization, WHO, held a congress on diet, nutrition and chronic diseases in February. Keep in mind that obesity and some chronic diseases such as diabetes or cardiovascular disease are directly related. The meeting warned that, along with obesity, chronic diseases are growing alarming, both in developed and developing countries. These diseases are mainly spread by diet and lifestyle changes.
According to data provided by the WHO, about 60% of deaths in 2001 were due to chronic diseases.
Against what was previously thought, these diseases do not only appear in the most developed countries: In sub-Saharan Africa, AIDS, malaria and tuberculosis are the leading causes of death, but in developing countries, chronic diseases account for 79% of deaths. In fact, cardiovascular diseases are more frequent in China and India than in developed countries, and in Asia, South America and some African countries, the number of obese has doubled or tripled since the last decade.
However, preventing chronic diseases is not impossible. The causes and risk factors for all types of obesity are unknown and some are immutable, but others are identified and may be modified. These risk factors include biological, social and behavioral agents, such as diet and sedentary lifestyle.
WHO believes that adequate physical exercise and feeding campaigns are not sufficient, although both measures are effective, governments, industries and social agents must work if substantial change is desired. If not all collaborate, it is very difficult to stop the increase in obesity and chronic diseases.
Obese or obese?
Obesity is a chronic disease caused by excess body fat. There are several ways to classify obesity, the body mass index being the most used, the BMI.
BMI is calculated by dividing the weight into kilos by the height square. For example, the IMD of a person 60 kilos and 1.7 meters high is: 60 / 1.7 2 = 20.7.
BMI classifies:
- 20: little weight.
- 20-25: normal.
- 25,1-26,9: overweight.
- 27-29.9 Primary obesity.
- 30-34.9: secondary obesity.
- 35-39.9: third degree obesity.
- 40: Fourth grade obesity, morbid.
Another type of classification of obesity is based on the distribution of fat. In fact, knowing where fat accumulates, the problems that obesity can cause are deduced.
The type of obesity depends on the division of the perimeter of the waist by the perimeter of the hips. If the result of this operation is greater than 0.9 in women and 1 in men, it is called ventral obesity and when it is inferior it is called peripheral obesity.
Abdominal obesity refers to bodies in the form of an apple. Most fat accumulates on the face, chest, and belly. According to experts, diabetes and cardiovascular insufficiency are the most common consequences of this type of obesity. Conversely, people with peripheral or pear-shaped obesity accumulate fat mainly in changes and thighs. Varicose veins and knee osteoarthritis are common in this type of obesity, but they have less risk of having a heart attack than the previous ones.
Finally, there are obese that have the fat evenly distributed in your body.
Anonymous said. “In addition to diet and exercise, psychological assistance is essential”
The mechanisms of control of hunger and saturation are becoming better known. Do you think this knowledge can lead to the short-term invention of a drug to treat obesity?
With what we now know about molecular biology, I do not think that at the moment there is the possibility of making an effective, safe and universal slimming medicine. Further research on genes and receptors must be carried out to propose how modulation occurs.
In fact, little is known about genetic mechanisms related to obesity. The genetic code has a great influence on diseases, while obesity has not been considered for many years as an evil but as a symptom. For this reason, not even genes related to obesity have been sought until recent years, and the treatments applied have not considered the problem as a whole.
As there are no miracle medications against obesity, the only solution is to combine diet and exercise?
No, treatment should not be limited to diet and exercise. On the other hand, I think that with them we should give psychological treatment, such as anorexia or bulimia. People do not see themselves as they are and feed themselves badly. This increases the risk of obesity in the future due to the alteration of the regulation system.
In addition, there is a lot to do in the media, I think the image of the media must be distorted. It seems impossible to succeed if it is not thin and tall. The dissemination of such ideas should be prohibited, as pro-alcohol ads are prohibited. Until all this is done, we are patching.
At the same time that the number of obese grows, cases of food alterations caused by the obsession of being thin are intensifying. Should messages addressed to society about these problems be unified?
Of course. To begin with, people have to know that many things that are said and are on the Internet are false, and to do this you have to do campaigns like those that are done to prevent traffic accidents or to report on cholesterol. For example, some herbs won't lose weight and, although they lose weight, they'll probably harm your health. People need to know that once clarified in any way, then an opposite effect occurs. In the end, the organism is not able to cope with this attack and compensate for the damage.
What has been the evolution of nutritional status in Euskal Herria?
When I started the thesis in 1986, there were morbid obese, but there were not many. 17 years later, there are much more obese and many obese, and the percentage of people with overweight or extreme thinness in the population of the Basque Country has grown enormously. That is very worrying, it means that we go backwards, where and in a culture where food is venerated. For example, if you send the sole to the plate, here it is accepted better than anywhere, since you do not have to do something that has not been done in tradition. That is why it is so striking and serious what is happening in Euskal Herria.
The food industry is also responsible. It negatively influences the nutritional status of the inhabitants of Euskal Herria, for example, because all foods are being enriched in something, adding vitamins or minerals. This poses a risk of future nutrition and health problems. In addition, dangerous messages like the one said in a dairy advertisement are disseminated: “I don’t have cholesterol.” Less evil than that is a lie, if I would not be dead!
With the possibility of eating well, the industry conditions food and it must be taken into account that the industry only seeks economic benefit.
More and more, before
The situation of childhood and adolescence is particularly worrying for WHO. In fact, in recent decades the proportion of obese grows enormously between children and young people, and manifests itself more and more young. In the Basque Country, 12% of young people under 18 are obese.
Obese in children is a risk factor to be obese also in adulthood. Therefore, treatment is not aimed exclusively at thinning but at adopting healthy habits for life. For this it is essential the participation of parents, since children must change their habits first.
On the other hand, many obese children have a distorted image of themselves and have difficulty accepting their body. In these cases it is necessary to provide psychological support, since otherwise there is a high risk that some years later other problems related to food occur, such as anorexia or bulimia.
To explain the increase in obesity we must take into account a number of factors: taking fast meals, candy and soft drinks, eating alone, watching television, not exercising…, all of them increase the risk of obese. Therefore, the key is to avoid them.
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Elhuyarrek garatutako teknologia
