Virtual Medical Centre

Assessing Central Obesity: Waist Circumference

• Introduction to waist circumference
• Central obesity/abdominal fat mass
• How does waist circumference compare to other obesity measurements?
• Measuring waist circumference
• Waist circumference cut-off levels

Introduction to waist circumference

Measuring a person's waist circumference (WC) is the simplest way to assess central obesity. WC has been shown to be one of the most accurate anthropometrical indicators of abdominal fat. It is closely correlated to the waist to hip ratio (WHR), but is thought to be a more reliable measure of abdominal fat; the WHR can mask the status of abdominal obesity with a disproportionately large hip circumference.

WC can also be used as a complimentary measurement tool to give additional information on body fat to people within the healthy weight range wanting to build muscle or improve their diet.

Central obesity/abdominal fat mass

Central obesity is an excess accumulation of fat in the abdominal area, particularly due to excess visceral fat. As visceral fat is supplied by the portal blood system, excess fat in this area can lead to the release of fatty deposits into the bloodstream. Fatty buildup in the blood is responsible for the majority of negative health consequences associated with obesity, such as:

• Type 2 diabetes
• Glucose intolerance
• High blood pressure
• Endometrial cancer
• Artherosclerosis
• Insulin resistance
• Altered metabolic profile
• Metabolic syndrome
• Cardiovascular disease
• Obesity-related lipid disorders (e.g. hypertriglyceridaemia; hypo-HDL-cholesterolaemia)

Central obesity is very common in elderly people because body fat is often redistributed to the abdominal region during the ageing process. On average, premenopausal women have half the abdominal fat of men; this is largely due to body shape. While women generally have a higher total and percentage body fat, it is more often located on their hips and thighs due to their pear-shaped bodies. Men naturally have an apple shape, and carry excess weight in their abdominal region.

How does waist circumference compare to other obesity measurements?

The standard measurement of overweight and obesity is the body mass index (BMI). The BMI is calculated using body mass and height, and the resulting score is an indirect measure of body fat.

However, there is not always a direct and clear correlation between total body fat and risk for obesity-related conditions. This makes BMI alone insufficient for determining the risk of serious conditions. Excess abdominal fat, on the other hand, will predispose obesity-related disease regardless of overall body fat. This highlights the importance of measuring WC. BMI remains the best indication of underweight and WC should not be used for this measure.

It is important to note that two people with very similar BMIs may vary substantially in the proportion of abdominal fat. Accordingly, a person with a BMI in the "normal" weight range may exceed the safe range of abdominal fat. A prime example of this is in older people. As lean muscle mass declines, their BMI may not change, but fat levels may be increasing with the accompanying redistribution of body fat.

Measuring waist circumference

Waist measurements should be taken as you breathe out. You should relax and not contract any abdominal muscles. Align the tape measure at the level of the belly button, and circle the whole way around the body and back to the starting point.

Waist circumference cut-off levels

As a general guide, increased obesity-related health risks are associated with a WC greater or equal to 94 cm in men and 80 cm in women. If a man has a WC greater than 102 cm, he is at a substantially increased risk, as are females with a WC greater than 88 cm. A WC greater than 120 cm for men and 110 cm for women puts these individuals at extremely high danger for obesity-related health issues.

Naturally, different ethnicities have different body builds and proportions. Therefore people of different ethnicities have different WC cut-off points. Asians have a naturally slimmer, petite frame and therefore the WC cut off for Japanese, Chinese and South Asian people is lower than for Caucasians. This means that if an Asian and Caucasian person of the same gender were both to have a WC of 94 cm, the Asian person would be at much greater risk of developing obesity-related disease.

Table 1: WC cut-off values for increased risk of metabolic syndrome and type 2 diabetes.