Normal weight obesity

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The prevalence of obesity has risen rapidly in recent years and shows no clear signs of slowing down; thus in the USA for example, the prevalence of obesity has increased from ~13% to almost 30% from the 1960s to present time.

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) 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 people can be calculated to have an ‘obese’ BMI while they actually have a healthy percentage of body fat. Conversely, a person can have a normal BMI and be in the normal weight range but actually have unhealthily high adiposity levels even though, 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 obesity, including diabetes, ischemic heart disease, heart failure, hypertension and sleep apnea. Catriona Thompson 19:50, 25 October 2011 (UTC)

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 simpler to use and 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 and preserved/ increased lean mass in patients with a BMI below 30kg/m2 - i.e. 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:

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

Disorders linked to NWO

When the fat content exceeds the lean muscle mass, and the body fat percentage is above 25% for men, and 35% for women, it is predicted that there is an increased risk of heart disease, diabetes, high cholesterol and high blood pressure. The possibility for these normal weight individuals to develop these conditions is said to be equivalent to overweight individuals.