Introduction
The mortality and morbidity associated with overweight or obesity have been known to the medical profession for more than 2000 years [1]. Overweight refers to a weight above the “normal” range. Although imperfect, calculation of the body mass index (BMI, defined as the weight in kilograms divided by height in meters squared), is widely accepted for the determination of underweight, normal weight, overweight, and obesity. Overweight is defined as a BMI of 25 to 29.9 kg/m2, obesity as a BMI of >30 kg/m2, and severe obesity is defined as a BMI >40 kg/m2.
Adult obesity is associated with a striking reduction in life expectancy, particularly among those who develop obesity when they are young (eg, <40 years old) .It has been suggested that the steady rise in life expectancy seen during the past two centuries may end because of the increasing prevalence of obesity .Individuals with obesity who also smoke have a substantially greater decrease in life expectancy compared with those without obesity who smoke and those with obesity who do not smoke .
The health hazards associated with obesity are reviewed here. Prevention and/or treatment of health consequences of obesity are an important component of the obesity management. The prevalence of and therapy for obesity, as well as the evaluation of the overweight patient, are discussed elsewhere:
Mortality
Relationship between weight and mortality — In general, greater body mass index (BMI) is associated with increased all-cause and cardiovascular mortality .
Cause-specific mortality — The association between BMI and cause-specific mortality was illustrated in the Prospective Studies Collaboration analysis. In the upper BMI range (25 to 50 kg/m2), each 5 kg/m2 increase in BMI was associated with a significant increase in mortality from coronary heart disease (CHD), stroke, diabetes mellitus, chronic kidney disease, and cancer (liver, kidney, breast, endometrial, prostate, and colon.
