11 March 2010

Does obesity protect against metabolic syndrome, rather than cause it?

Traditionally, it is believed that the complex of symptoms that make up the metabolic syndrome (resistance of tissues to insulin, high cholesterol, increased fat content in the liver, as well as a high risk of diabetes and heart disease) contributes to the development of obesity. However, according to the data published on March 9 in the journal Trends in Endocrinology and Metabolism in the article "Gluttony, sloth and the metabolic syndrome: a roadmap to lipotoxicity", in reality things are quite different.

According to the author of the article Roger Unger, obesity is the result of the body's desire to accumulate fat exactly where it should be – in adipose tissue. The purpose of this aspiration is to protect the organs from the toxic effects of lipids. A cascade of symptoms, known as metabolic syndrome, develops only in cases when the body receives such an excess of calories, which adipose tissue is not able to cope with.

In recent years, residents of the United States and other developed countries have led a sedentary lifestyle and consume a large number of foods rich in carbohydrates and fats. Human metabolism, which continues to store fat for a "rainy day" in the old-fashioned way, is sometimes capable of incredible things, but in some cases it malfunctions, leading to the development of metabolic syndrome. Anger, who first proposed the term "lipotoxicity" in 19994, believes that the epidemic of obesity and metabolic syndrome can only be stopped by a global change in the lifestyle and diet of the population.

The author cites many proofs of the protective role of obesity. For example, genetic manipulations that stimulate the formation of adipose tissue in mice have demonstrated that active adipogenesis (the formation of fat cells) delays the onset of the metabolic consequences of overeating. Conversely, a violation of the processes of adipose tissue formation in obesity-resistant rodents in conditions of excess calories leads to the accumulation of lipids in various organs and the development of severe forms of diabetes.

There is no consensus among experts on whether insulin resistance is the main cause of the development of metabolic syndrome or just one of its symptoms. However, Anger believes that the decrease in the sensitivity of cells to insulin is just a "passive by–product" of the accumulation of fat in the liver and muscle tissue, which occurs when the mechanisms of lipid storage in fat cells are disrupted.

The key moment of the transition of protective obesity into metabolic syndrome is the development of tissue resistance to the appetite-suppressing hormone leptin. This hormone also regulates the distribution of adipose tissue in the body. An increase in the level of leptin as fat deposits increase is an adaptive reaction, which, however, only works up to a certain point, after which the tissues acquire resistance to this hormone.

The genetic characteristics of a person determine his ability to cope with excess fat: many overweight or even obesity are not accompanied by other symptoms of metabolic syndrome. However, sooner or later, any fan of fast food inevitably faces the need to cut the calorie content of the diet.

Moreover, at a certain age (at the end of the reproductive period), leptin resistance develops in almost every person, therefore, diet and regular physical activity are of particular importance for the elderly.

At the end of his review, Anger writes that numerous facts indicate that the most common forms of metabolic syndrome and type 2 diabetes develop as a result of the continuous intake of a huge amount of calories into the body, complicated by the loss of the ability of adipocytes to accumulate lipids and thus protect the body from the effects of lipotoxicity. Over the past 50 years, access to cheap food rich in fats and carbohydrates has led to the appearance of more than 200 million obese people in the United States alone and more than 50 million with metabolic syndrome. Anger believes that it is possible to combat this problem only by raising prices for "junk food", but simultaneously increasing the availability of "healthy food" for low-income segments of the population is a difficult problem.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru according to ScienceDaily: Obesity as Protection Against Metabolic Syndrome, Not Its Cause.


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