Body Mass Index : Is a fresh approach needed?

03 June 2013 Dr Peter Bond, Old Mutual

Why is body mass index so important? Dr Peter Bond, Chief Medical Officer at Old Mutual, explains.

A high body mass index (BMI) may lead to diseases that could affect an underwriter’s assessment of a client’s risks, resulting in exclusions or higher monthly premiums.

There are other ways to assess health risks, but BMI remains a most valuable measurement for overall risk assessment.

It may be difficult to understand potential health risks associated with either a low or a raised BMI, especially when the person concerned looks healthy and has no history of significant health conditions.

A low BMI is mostly easily explained and usually indicates some other underlying illness.
A raised BMI, however, may be the only current pointer to a significant risk for cardiovascular or other diseases.

BMI greater than 30 is a cause for concern because obesity is associated with hypertension, Type 2 diabetes, and abnormal blood lipids or fats. Also, excess fat tissue has a biochemical or hormonal effect that can give an irregular appearance to tissue cells in certain organs.

In a group of people with BMIs greater than 30, the following applies:
• the risk for developing high blood pressure increases by 46% in men, and 75% in women;
• the risk of developing heart disease increases by 40% in men, and 64% in women;
• the risk for Type 2 diabetes doubles for each 10kg of weight gained;
• weight gain is a significant risk factor for the development of certain types of cancers, particularly in women;
• obesity leads to early joint damage;
• obstructive sleep apnea is clearly linked to obesity;
• peripheral venous disease is aggravated by obesity.

The pie chart represents the population of the US, which is similar to the insured population group in South Africa.

Estimated Percentage by BMI

• Normal weight or underweight (BMI under 24.9)
• Overweight (BMI of 25 to 29.9)
• Obesity (BMI of 30+)
• Extreme obesity (BMI of 40+)
Source: NHANES, 2009–2010

How it is done

Measuring a person’s BMI simply requires measuring his or her waist circumference, taking a circumferential line midway between the belly button and the lower end of the breastbone, parallel to the floor.
Girth size is a good indicator of the fat around the abdominal organs, which in turn is a good indicator of the risk of developing cardiovascular disease.

A waist circumference in men greater than 94cm is considered overweight, and more than 110cm is obese, while in women a girth above 80cm is considered overweight, and over 88cm is obese.

Waist circumference should be measured accurately so that those who mainly have lean muscle increase causing the raised BMI will not be deemed to be at any greater risk than the normal population. These individuals should be identified by a normal or marginally raised waist circumference.

Additional input for girth

Because of the real and significant health risks associated with a raised BMI, some insurers, including Old Mutual, introduced an additional input for girth on a standard medical report, alongside a person’s height and weight, to assess the individual’s risk profile more accurately for life insurance cover.

An elevated BMI would cause the underwriter to load the mortality aspect of the premium in many cases, which will often cost the client more.

Underwriters endeavour to look for credits and are often under pressure to reduce the loading, but this is not always possible. The risks associated with obesity cannot be ignored. If, however, a loading was imposed, but after inception of the policy a client’s BMI changes due to a lifestyle change, some policies, including the Greenlight life cover from Old Mutual, would review the existing loading.

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