The American Heart Association Numbers

Bodyfat composition for MenBodyfat composition for Women
No added health risk:up to 20%up to 27%
Potential (slight) risk:20-25% 27-32%
Moderate risk: 25-30% 32-37%
High risk: greater than 30% greater than 37%
Both ACSM and AHA use the definition of obesity as the percentage of body fat at which the risk of obesity-related disease increases (such as coronary artery disease (CAD)).

It should be noted that to a certain point the scale represents a continuum, and as the %bodyfat goes up, so does the risk. Thus, 25% and 26% are not all that different in terms of risk, despite the initial classification of one for males as "slight" vs. "moderate".

However, once one gets below the lower bound (20% for men, 27% for women) lower levels of bodyfat, while potentially desirable to a point, do not seem to reduce the risk of disease further.

Different organizations use different data, and the exact cutoff points may vary somewhat, but the basic message is the same - excessive amounts of bodyfat can predispose the individual to a higher risk of CAD, but beyond a certain point health risks no longer dominate and the primary consideration becomes one of aesthetics.

Of course, the "ideal" %bodyfat numbers people bandy about for health and fitness are considerably lower, and are based upon various aesthetic and performance standards. For example, AFAA recommends 12-15% for men, and 18-22% for women. Other organizations' numbers vary somewhat, but hover near this range.

It is important to remember that some minimal amount of body fat is essential to maintain life processes - proper functioning of the endocrine and nervous systems depend on a certain amount of bodyfat. Again, the estimates vary, but 3-5% for men and 8-11% for women are generally accepted as the lowest levels that will sustain life. It is not recommended that people keep their bodyfat this low, but it does give one an idea of the lower bound.

Disclaimer

The information is not a substitute for medical advice. You are responsible for protecting yourself from injury to yourself. We strongly recommend that you discuss this with your doctor before implementing it as part of your exercise routine.
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