For centuries, being overweight has been considered the result of a character flaw, of the obese person’s inability to control their impulses, and weight control, a question of arithmetic: what goes into the mouth minus what is burned. “More sole and less pot”, summarizes the popular saying. However, scientific work in recent decades has shown that this solution may be attractive, but it is not a solution. One of the most relevant discoveries about the regulation of appetite, which makes some hungry at all hours and others effortless ascetics, was leptin, known as the satiety hormone. In an interview in EL PAIS, Jeffrey Friedman, the man who discovered the molecule in 1994, stated that obese people are obese because they eat too much, but he recalled the key question: “Why do they eat too much?”
Leptin is part of the molecular mechanism that tells us when to eat and when to stop, and we don’t all receive the same signals. “Our weight is regulated by genes, in the same way as height. You wouldn’t ask someone who is 1.90 meters tall to be 1.80 meters tall, because that’s how they are,” Friedman exemplified. In recent decades, the percentage of people with obesity and overweight has increased. Although there are those who suggest that this epidemic is the reflection of a decadent society full of individuals lacking willpower, scientists who study the phenomenon in depth know that this is a lie and that the solutions are beyond proverbs and common sense.
In its last August issue, the magazine Science has published an analysis by several experts in which they make surprising statements. Despite great advances in the knowledge of the disease, such as the discovery of leptin, “there is little consensus on the causes” of the obesity pandemic, they write, and they assure that, “although it is often stated that increasing sedentary lifestyle is one of the main causes of the obesity pandemic, this is not at all clear and the current evidence does not support this conclusion. John Speakman, one of the authors of the article, states by email that “the data shows that when people become more obese, they become less active, but the cost of moving increases.” “In the end, these two factors balance each other out, and when you take the effect of body mass out of the equation, as the pandemic has progressed, the energy expended through physical activity has increased slightly (since the 1980s),” he says. .
We are not a bank account. In another article published this year, the researcher from the University of Aberdeen (United Kingdom) attributed part of the imbalance between energy consumption and expenditure that causes obesity to a decrease in the basal metabolic rate, energy expenditure at rest, in recent years. 30 years. Increasing it would be a strategy to combat the pandemic, but it is not clear what has caused its decrease. As a hypothesis, they propose that less exposure to infectious diseases has reduced our investment in immune defenses or that changes in diet, such as reduced consumption of saturated fats, have something to do with it.
“Now, we see it as a social disease in which there is an influence between genes and an obesogenic environment with a lot of variability between people”
Cristobal Morales, Virgen de la Macarena hospital in Seville.
Recognition of the complexity of the problem has a first consequence, which is the change in the treatment of patients. “In the old approach to obesity, when it was treated as if it were a checking account, with entries and exits, something was done that is not usually done with other diseases: the patient was blamed,” says Cristobal Morales, an endocrinologist at the Virgen Hospital. of the Macarena of Seville. “Now, we see it as a social disease in which there is an influence between genes and an obesogenic environment with a lot of variability between people,” he adds. Decades of treating the disease as a matter of personal responsibility have shown that this is not the way to combat the pandemic.
Personalized treatment. A second consequence, perhaps longer term, is the application of personalized medicine to the treatment of obesity. “Right now, there is no distinction, and people with obesity are all grouped together in the same way and then, as in all diseases, not all patients respond the same to different treatments,” explains Ruben Nogueiras, researcher at the University of Santiago de Compostela. “With new anti-obesity drugs, some patients lose up to 20% of weight, as with bariatric surgery, others do not respond as much and others do not respond at all,” continues Nogueiras. “The ultimate goal is to better classify patients to provide personalized treatment,” he concludes.
Institutions such as the Mayo Clinic, in Rochester, Minnesota, (USA), already propose separating people with obesity into four main types. First, that of the “hungry brain”, influenced by signals between the brain and the intestine, which requires an excessive amount of calories to achieve satiety. Second, emotional hunger, when food is used to deal with negative and positive emotions. Third, that of “hungry stomach”, when satiety does not last as long as it should. And fourth, that of people with low energy consumption at rest.
Metabolism, genes and environment. Manuel Tena-Simpere, researcher at the University of Cordoba, also remembers that the components that control body weight, such as leptin, are not only related to factors that help maintain a balanced weight. “It was thought that some hormones such as leptin increased almost automatically with eating, but it has been seen that their levels are related to aspects such as the pleasure of eating and that means that not all individuals have the same eating patterns. These components make some people tend to eat in a more compulsive way,” he says.
The authors of the article Science They warn of another type of arithmetic simplification that can befall when applying knowledge about obesity. It is possible that the different forms of energy expenditure (physical activity, expenditure at rest and thermoregulation, with the key role of brown fat) may not be related to each other, so that they can be added and subtracted as if the changes in each of them were independent of the others. “Increasing one aspect of expenditure can cause compensatory decreases in other components or changes in intake,” they point out.
“Obesity as a disease should not be confused with the social desire to be thin”
Guadalupe Sabio, National Cardiovascular Research Center of the Carlos III Institute
In this disease, the result of the interaction between genes and the environment, some facts remain poorly understood, such as the ability of ultra-processed food to make us consume more energy. Some combinations of nutrients that do not exist in nature and reprogram brain regions that regulate motivation and reward cause overconsumption, but the mechanisms behind them are unclear. It is also not known what influence sweeteners have on weight gain and diseases associated with obesity. “They have effects on glucose metabolism. It greatly worsens insulin sensitivity, and favors insulin resistance and the appearance of type two diabetes,” says Nogueiras.
Industrial chemical compounds. Other elements suspected of influencing the obesity pandemic are endocrine disruptors, a large number of chemical compounds such as bisphenol A or PFAS, which are used in plastic packaging, can covers, and countless other products. These substances “alter hormonal function and a large part of body weight is regulated by hormones,” explains Nogueiras. “Some endocrine disruptors also affect diseases associated with obesity such as fatty liver or diabetes. It is a field with room to learn, but the results that are appearing are going in the same direction,” he adds. Guadalupe Sabio, researcher at the National Cardiovascular Research Center of the Carlos III Institute of Madrid, agrees: “Hormonal disorders are very important, it is seen in women during menopause, which changes where the fat accumulates or if the fat is going to be inflamed.”
Better understanding the role of some industrial products in the pandemic would provide arguments for the administration to regulate their use, as is the case with ultra-processed foods. In addition to taking advantage of the effectiveness of bariatric surgery or the new medications for obesity, the successful GLP-1 agonists, public policies will be necessary to control a social problem. To begin with, Sabio emphasizes the importance of “treating obesity as a disease and not blaming the patient,” although he points out that “obesity as a disease should not be confused with the social preference for being thin.” For now, the State does not consider obesity a disease, and does not fund GLP-1 agonists to treat it.
The article by Speakman and his colleagues addresses the social part of the disease and points out some of the mysteries that surround it. In richer countries, the poor are more likely to be obese than the rich, but the opposite is true in the poor. The stress and stigma associated with being fat can promote the development of obesity. In this sense, obesity has an important hereditary factor, due to genetics, but also due to social conditions. Tena points to factors such as sex: “Historically, metabolism studies have been done in the male sex and we see that hormonal factors are key to the predetermination of obesity.” And she believes that it is important to anticipate “early risks that are inherited from the individual’s mother, father or grandfather and that could be reduced by acting preventively.” Speakman points out that studies in mice “show that maternal obesity and her diet influence offspring susceptibility to obesity, possibly through epigenetic mechanisms, but whether this applies to humans is uncertain.”
Despite the large number of uncertainties surrounding the great pandemic of the industrial era, experts agree on the great advances of recent times, which open the door to effective drugs and help overcome simplistic and unhelpful approaches. Individual responsibility will still be relevant, as it is in the treatment of any chronic ailment, but it cannot be the focus. According to data from the Spanish Society for the Study of Obesity, around 80% of diet attempts fail and the figures may be worse if follow-up is carried out over a very long term. Instead of thinking that the fault lies with the people who do not apply the solutions they are offered, perhaps it is time to ask ourselves if we are understanding the problem.
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Source: EL PAIS