The Exercise Prescription – Part 14 – Screening Tests

Screening Tests for Body Fat and Body Mass

No matter what anyone says or amount of brainwashing from the media – being overweight and out of shape is NOT healthy. Do not be fooled into this belief.

It would be ideal to be able to track progress and have baseline and ongoing screening tests. Though, not necessary.

The minimalist way of tracking progress is to take your weight every day and take periodic pictures in a mirror. The best way to measure weight on a scale is first thing in the morning, without clothes, after you urinate. It will be the most consistent weight obtainable if this is done.

There are of course more sophisticated ways of measuring body fat, muscle mass and bone density. A DEXA scan is considered the gold standard for measuring this and keeping track of progress. The other added benefit of a DEXA is its ability to measure visceral fat in the abdomen that could be high in what appears to be an otherwise healthy, skinny individual. Nonetheless, high visceral fat is associated with diseases of aging, such as cancer, cardiovascular disease, and diabetes. The DEXA however accurate it is, has not been proven to a correlate for developing disease.

The DEXA has a radiation dose that is approximately 1.75% of what normal background radiation dose we all experience in one years’ time. Keep this in mind if radiation exposure is a concern to you. It is very low compared to other imaging modalities such as x-ray or CT scan especially.

The BMI calculation is not accurate in measuring body fat but when looked at from an epidemiological point of view it has some correlation with developing disease. It should be completely done away but the World Health Organization insists on keeping it around as a public health measurement tool. However, different from the classifications of the WHO, the best threshold for obesity is a BMI of 24 in women, and 28 in men.

Other techniques include a skin fold analysis with a pair of calipers. There are a number of calculations available. Error rate is about 3.5%. A Bioelectrical impedance analysis is another common method, but the amount someone is hydrated can affect the calculation. The benefits of both methods are they are more accurate and cost effective.

Do not believe everything you hear from the media.