The incidence of obesity has increased significantly in recent decades, reaching epidemic proportions. Obesity is defined as an increase in fat mass that affects the health of the body. People who have a body mass index >30 kg/m2 (calculated by dividing the weight in kilograms by the square of the height in meters) are considered obese. The higher the body mass index above the aforementioned limit, the greater the effect of obesity on health. A gradual increase in obesity is observed in developed and developing countries of the E.U. possibly related to economic development, urbanization and the effects of these changes on the lifestyle and diet of the entire population. Approximately 22.5% of adults are within the limits of obesity (BMI≥30 kg/m2) which significantly affects cardiovascular health and increases mortality.

Obesity is a strong independent predictor of cardiovascular disease even in the absence of other risk factors such as smoking, diabetes mellitus, dyslipidemias, etc. Researchers and clinicians have historically emphasized that increasing body mass has serious implications for the prevention and progression of cardiovascular disease. Contrary to this line of thinking, this assumption appears not to be entirely correct. Many studies have shown that obesity can play a protective role when it coexists with some cardiovascular disease. This phenomenon was called “The obesity paradox” (obesity paradox). The obesity paradox has been studied in patients with heart failure and coronary artery disease, as well as in patients with arterial hypertension, atrial fibrillation, pulmonary arterial hypertension, and congenital heart disease.

At this point it is necessary to clarify the fact that the World Health Organization (WHO) defines as obese people who have a body mass index above a certain limit, without taking into account the ratio of the components that make up each organism – and more specifically the ratio of fat in relation to other tissues, such as muscle mass – as well as the distribution of fat in the body. For this reason there are patients with a similar body mass index and a similar total fat mass, but with a completely different cardiovascular risk profile. Thus, the accumulation of e.g. visceral fat has been identified as a major metabolic risk factor with atherogenic and deleterious properties in cardiac function. In contrast, the accumulation of subcutaneous fat, as well as the weight added to an organism by increased muscle mass, does not seem to be as harmful as visceral fat.

Protective properties

Although there is no doubt that obesity plays a decisive role in the development of heart failure and is associated with the aggravation of factors that lead to the appearance of cardiovascular diseases, it may also have some protective properties in some cases.

This paradoxical association has mainly been demonstrated in patients with mild obesity (ie with a body mass index up to 35 kg/m2). The obesity paradox in heart failure has mainly been observed in patients with advanced disease, where the presence of increased weight was associated with better prognosis compared to patients who were normal weight or underweight.

The molecular mechanism through which increased body weight may improve prognosis in some patients with cardiovascular disease has not been fully elucidated in the literature. The most basic hypothesis, however, is that increased muscle mass and the correct distribution of fat lead to improved cardiorespiratory fitness in the body, which leads to significantly improved long-term results. Conversely, when the increased body weight is mainly due to the accumulation of visceral fat and is combined with reduced muscle strength, then proteins with an inflammatory effect are secreted into the blood, which can directly worsen systolic and diastolic cardiac function, as well as lead to the formation of atheromatous plaques in the arteries.

Undoubted enemy

In conclusion, when increased body weight and heart failure coexist, the prognosis in some of the patients defined as “mildly obese” may be better than in those who are of normal body weight or are lean. It is obvious that the obesity paradox cannot under any circumstances be a role model for the general population and especially for patients without established cardiovascular disease. After all, it is proven that if obesity had been prevented, it would have led to fewer patients with cardiovascular disease in the first place. It therefore becomes very important to develop exercise and diet strategies that will lead to an improvement in the body’s cardiorespiratory fitness and in improving the ratio of visceral fat mass to non-visceral body fat mass, thus shielding the health of the population to be able to have a better prognosis if and when any cardiovascular disease occurs.