WHAT IS OBESITY?

Almost every week there is an article published in a major national newspaper on the epidemic proportions reached by obesity in various countries. The pathophysiology of obesity is complex and some people are more prone to accumulate excess fatness and to develop related metabolic complications than others. However, despite individual differences in genetic susceptibility to body fat accumulation, it has become obvious that the epidemic proportions reached by obesity is partly the result of a pronounced reduction in the level of daily physical activity as we have engineered for ourselves a very comfortable sedentary environment. For example, most of us are now sedentary during working hours and we use transportation devices (cars, trains, planes) to go from one place to another. In addition, what was centuries ago a constant daily struggle (getting access to food, sometimes in limited quantities) has become very easy: we are surrounded by energy dense, refined foods which promote the passive overconsumption of calories. Therefore, an environment favouring minimal energy expenditure but facilitating overeating largely contributes to the worldwide epidemic of obesity.

However, although it is generally perceived that obesity causes prejudice to health, this condition has, for a long time, left cardiologists rather perplexed. For example, although epidemiological studies have shown that an excess relative body weight (the most commonly used index being the body mass index (BMI) expressed in kg of body weight divided by height in m²) is associated with increased mortality and comorbidities such as hypertension, dyslipidemia and diabetes,^w1–4 obesity assessed by the BMI has often failed to be identified as an independent risk factor for cardiovascular disease (CVD), once adjustments are made for the presence of comorbidities. There are two possible explanations for the weak independent association between obesity and CVD. First of all, it is possible that the …