What exactly is Obesity ?

Obesity is a condition in which excessive body fat has accumulated to the level that it may have an adverse effect on health, leading to reduced life expectancy and/or raised health problems.

Measurements of obesity

Obesity represents a condition associated with excess storage of body fat. Although similar, the term overweight is puristically thought as an excessive amount ofbody weightfor height. Normal, healthy men have a body fat proportion of 15-20% , while normal, healthy women have a percentage of about 25-30%.[4] Nevertheless, because differences in weight involving individuals are simply partly caused by variations in body fat, body mass is really a limited, although easily obtained, index of obesity.

The ways to establish obesity is to work with this technique of measurement are :

1.            The body mass index (BMI) , also known as the Quetelet index, is needed far more usually than body fat percentage to determine obesity. Generally, Body mass index correlates intimately with the level of body fat in most settings; however, that correlation is weaker at low BMIs.

The individual’s BMI is calculated as bodyweight (kg)/height(m2)

, with weight in kgs and height in meters (in any other case, the equation is weight in pounds ´ 0.703/height in inches2). Online BMI calculators can be found.

2.            Deurenberg formula, as follows:

body fat percentage = 1.2(BMI) + 0.23(age) - 10.8(sex) - 5.4

with age in years and gender being designated as 1 for males and 0 for women. This equation has a standard error of 4% and accounts for more or less 80% of the variation in body fat.

Although the BMI typically correlates closely along with percentage body fat in a curvilinear fashion, some important caveats apply to its interpreting. In mesomorphic (muscle) people, BMIs have a tendency to show over weight or slight obesity could be spurious, whereas in some individuals along with sarcopenia (such as, aged men and women and persons of Asian origin, especially from South Asia), a typically normal BMI may cover up actual excessive adiposeness seen as a an elevated proportion of fat mass and decreased muscle mass.

In view of those disadvantages, many authorities recommend a definition of obesity depending on percentage of body fat. For men, a percentage of body fat in excess of 25% identifies obesity, with 21-25% becoming borderline. For women, in excess of 33% defines obesity, along with 31-33% staying borderline.

3.            Some standard skin thicknesses

Subscapular, triceps, biceps, suprailiac) and also numerous anthropometrical measurements, of which midsection and hip circumferences are the most significant. Skinfold measurements are the least correct signifies by which to assess obesity.

4.            Dual-energy radiographic absorptiometry (DXA) scanning is used principally by researchers to accurately measure entire body composition, particularly body fat mass as well as fat-free mass. It offers the additional benefit of measure regional body fat distribution. However, DXA scans can't be utilized to separate between subcutaneous and visceral abdominal fat deposits.

5.            Abdominal computed tomography (CT) scanning (at L4-L5) as well as magnetic resonance imaging (MRI) methods. An easier technique, using bioelectrical resistance, was lately introduced. However,these methodsare 1 clinical research.

Classification of obesity

Although several classifications and definitions for degrees of obesity are accepted, the most widely accepted classifications are those from the World Health Organization (WHO), based on BMI. The WHO designations include the following:

Grade 1 overweight (commonly and simply called overweight) - BMI of 25-29.9 kg/m2

Grade 2 overweight (commonly called obesity) - BMI of 30-39.9 kg/m2

Grade 3 overweight (commonly called severe or morbid obesity) - BMI greater than or equal to 40 kg/m2

Etiology

The etiology of obesity is far more complex than simply an imbalance between energy intake and energy output. Although this view allows easy conceptualization of the various mechanisms involved in the development of obesity, obesity is far more than simply the result of eating too much and/or exercising too little (see the energy-balance equation, below). Possible factors in the development of obesity include the following: Metabolic factors, Genetic factors, level of activity, Endocrine factors, Race, sex, and age factors, Ethnic and cultural factors, Socioeconomic status, Dietary habits, Smoking cessation, Pregnancy and menopause, Psychological factors, History of gestational diabetes, Lactation history in mothers.

Prognosis

For a person with a BMI of 25-28.9 kg/m2, the relative risk for coronary heart disease is 1.72. The risk progressively increases with an increasing BMI; with BMIs greater than 33 kg/m2, the relative risk is 3.44. Similar trends have been demonstrated in the relationship between obesity and stroke or chronic heart failure.

Overall, obesity is estimated to increase the cardiovascular mortality rate 4-fold and the cancer-related mortality rate 2-fold.[54] As a group, people who are severely obese have a 6- to 12-fold increase in the all-cause mortality rate. Although the exact magnitude of the attributable excess in mortality associated with obesity (about 112,000-365,000 excess deaths annually) has been disputed, obesity is indisputably the greatest preventable health-related cause of mortality after cigarette smoking.

For persons with severe obesity (BMI ≥40), life expectancy is reduced by as much as 20 years in men and by about 5 years in women. The greater reduction in life expectancy for men is consistent with the higher prevalence of android (ie, predominantly abdominal) obesity and the biologically higher percent body fat in women. The risk of premature mortality is even greater in obese persons who smoke.

Some evidence suggests that, if unchecked, trends in obesity in the United States may be associated with overall reduced longevity of the population in the near future. Data also show that obesity is associated with an increased risk and duration of lifetime disability. Furthermore, obesity in middle age is associated with poor indices of quality of life in old age.

Individuals who have abdominal obesity (elevated waist circumference) are at risk for obesity-related health complications. Most individuals with a BMI of over 25 and essentially all persons with a BMI of more than 30 have abdominal obesity.

Factors that modulate the morbidity and mortality associated with obesity include the following:

 Age of onset and duration of obesity, Severity of obesity, Amount of central adiposity, Comorbidities, Gender, level of cardiorespiratory fitness, Race.

Weight-loss programs

Most individuals are able to attain weight loss in the short term, but weight regain is unfortunately a common pattern. On average, participants in nonsurgical weight-management programs lose approximately 10% of their initial body weight over 12-24 weeks, but the majority regain two thirds of the weight lost within a year.

Old data indicated that 90-95% of the weight lost is regained in 5 years. Recent data show that more intensive and structured nonsurgical weight management may help a significant number of patients to maintain most of the weight lost for up to 4 years.

In the Look AHEAD study, 887 of 2570 participants (34.5%) in the intensive lifestyle group lost at least 10% of their weight at year 1. Of these, 374 (42.2%) maintained this loss at year 4 and another 17% maintained 7-10% weight loss at 4 years. More than 45% of all intensive lifestyle participants had achieved and maintained a clinically significant weight loss (≥ 5%) at 4 years.