The Truth about BMI and the Emergence of the Fat-Fit Complex

In 1999 a significant research project (Wei et al., 1999) found cardiorespiratory fitness to be a far superior predictor of death from all causes (all-cause mortality) than Body Mass Index (BMI).

This relationship exists to the extent that relative risk of all-cause mortality is doubled for those individuals who are unfit and ‘normal’ weight in comparison to those individuals who are fit and 'obese'. Also interesting was that the researchers found an ‘unhealthy’ BMI score significantly increased the chances of all-cause mortality only in individuals who failed to exercise regularly at a moderate intensity.

What is Significant about this Research?

This research tells us that exercise and fitness levels are far superior indicators of health than the very simple mathematical equation of BMI. Furthermore, Wei et al.'s research disproves the common belief that fitness is something you can visually see and that it is possible to be in a fit and healthy physical condition at the same time as being obese. Recent reviews of cutting-edge research (Gleeson et al. and Hardman & Stensel) similar to that conducted by Wei et al. suggest that weight loss achieved through regular exercise is of little importance for health in comparison to the unseen physical benefits that assist in preventing cancer, type II diabetes, cardiovascular disease, and improving immune function. Hardman and Stensel go as far as suggesting that a single exercise session of at least moderate intensity can have a medical ‘dose response’ in preventing most diseases that can lead to health-related death.

What are the Implications of this Research?

Through regular exercise it is possible for both fat and obese individuals to be in a healthier physical condition than someone of normal weight that is physically inactive.

The most important benefits associated with exercise are the ones which you can’t visually see.

Weight and BMI are only significant indicators of health when you don’t participate in moderate intensity exercise on a regular basis.

References

Gleeson M., Spurway N., MacLaren D. (Eds.) . Immune Function in Sport and Exercise: Advances in Sport and Exercise Science Series. London: Churchill Livingstone.

Hardman A., Stensel D. . Physical Activity and Health: The Evidence Explained (Second Edition). London: Routledge.

Wei M., Kampert J., Barlow C., Nichaman M., Gibbons L., Paffenbarger R., Blair S. (1999). Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men. Journal of the American Medical Association; 282 (16): 1547-1553.

Image credit: What’s a Healthy BMI in Adults?