Normal weight obesity

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The prevalence of obesity has risen rapidly over the years and shows no clear signs of slowing down. A great epidemiological representation of that can be seen in studies using the population of the US of A, collected from the 1960s to present time. It has shown that obesity in the population has increased from ~13% to almost 30%.

To clinically classify a person as being obese, their Body Mass Index (BMI) must be equal to or greater than 30kg/m2. However, the spectrum of obesity is quite large. Normal Weight Obesity (NWO), found in almost half of the American adult population, is when a person has a normal BMI (18.5- 24.9 kg/m2) or normal body weight but also has a high percentage of body fat(>23.1% for men and >33.3% for women) as well as heart and metabolic disturbances.

Measuring an individual’s BMI does not take into account a person’s muscle or bone mass and as both are denser than fat and so men, in particular, can be calculated to have an ‘obese’ BMI while they actually have a healthy percentage of body fat. In contrast to this, a person can have a normal BMI and be in the normal weight range but actually have unhealthily high adiposity levels but according to their calculated BMI, they are not obese. High percentages of body fat tissue are high risk factors for the diseases and disorders linked to the obesity, including diabetes, ischemic heart disease, heart failure, hypertension and sleep apnea.

Measuring Normal Weight Obesity

Sawdah Jakda 16:04, 25 October 2011 (UTC)

The gold standard definition of obesity is considered to be an excess in Body Fat (BF) but the BMI is used by clinicians and epidemiologists as a means of defining the presence of adiposity and/or obesity. The advantages of using the BMI instead of BF values is that it is a lot more simple to use and it is easy to reproduce. Studies showing the association between extreme BMI values and increased mortality further support its usage. However, this test fails to differentiate between elevated BF content and preserved/ increased lean mass in patient with a BMI below 30kg/m2, those not clinically classified as obese.

The strong relationship between high Adiposity and metabolic disturbances makes it vital to try find a more accurate way in which to determine adiposity other than BMI.

The definition of metabolic syndrome covers the following criteria's:

1) Waist circumference (>102 in men and >88 in women)

2) HDL (<1.04mmol/L in men and <1.03mmol/L in women)

3) Triglycerides (>1.7mmol/L)

4) Blood Pressure (systolic blood pressure >130mmHg or diastolic blood pressure >85mmHg)

5) Fasting Glucose (>5.5mmol/L)