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Defining the Relationship Between Good Health, Fitness and Leanness
Can We Ever Really be Too Thin?

While this question may seem a simple one to many of us, just ask this question to your women friends, and, you may hear a resounding "Never!".

During the second half of the 20th century, our society has placed a great emphasis on being thin. We have discriminated against and ridiculed obese women (and men!), while placing thin women on a "pedestal of perfection". This obsession with thinness has led to a generation of weight-obsessed, anorexic, bulimic, and eating-disordered women and girls. While we all know that being too thin (or too fat) is not healthy, there seems to be very little public knowledge about what level of thinness equates with good health and fitness.

How lean should women really be?
Women are genetically pre-determined to have a greater amount of body fat than men. Women need more body fat in order to maintain the normal reproductive processes of menstruation and pregnancy. In addition, fat is absolutely essential for many other human physiological processes such as nerve conduction, insulation of organs and insulation from cold, proper skin health, and transport of vitamins, to name a few.

The amount of body fat we consider necessary for normal physiological functioning is called "Essential Fat." 8-12 % body fat is considered Essential Fat for women. Men generally need 3-8% Essential Fat.

Other ranges of body fat correlate directly with health and fitness levels. For example, 12-18 % body fat is considered very lean for women, with 12% being the borderline for potential poor health. Excellent health is generally associated with the lean category of 18-22% body fat in women, and is much more realistic and achievable than lower levels. Body fat levels of less than 18% are usually seen in highly trained women athletes and should not be part of our general fitness expectations. Average, or normal, body fat for women is 22-26%, with 26-30 % being above normal. Body fat levels above 30% are equated with clinical obesity.

Scales don't tell us the truth
When we say leanness or thinness, we often think of what we weigh on a scale. However, the

scale cannot determine what amount of our weight is fat, and what part is heavier muscle and lean tissue. Without this knowledge, the scale weight can have little relevance to good health and fitness.

In the past, health insurance standards used scale weight as an indicator of health. This correlation became obsolete when we became knowledgeable about the importance of the relationship between body fat and lean tissue and its accuracy as an indicator of fitness and health.

In general, if your body fat falls within the average to lean categories, then whatever you weigh on the scale is appropriate for your body frame, and, you are most likely in excellent health.

Body Fat Levels Chart

Unfortunately, many women fall well within these wonderful ranges and still believe they are over fat. Some of them believe that 12-18% is most desirable. In reality, it may be unachievable, unrealistic, and a prelude to eating disorders and poor health. Women who attempt to maintain body fat levels of less than 15%, are more prone to serious illness, injury, and fatigue. Chronic injuries, illnesses, mental and physical burnout, fatigue and amenorrhea all result from inadequate body fat.

Without question, obesity is an epidemic here in the U.S., costing us hundreds of millions of dollars each year in insurance and health care costs as well as time lost from work and school. But let’s not go to the other extreme. Can we ever be too thin? Absolutely!

If you are not sure where you stand in the "spectrum of leanness", ask a certified fitness professional to assess your body composition. The results will be much more accurate than any mirror or scale!

Kathleen Ekdahl is an AFAA and ACE Certified Fitness Instructor and Personal Trainer with over 12 years experience in fitness and a background in Clinical Research and Cardiovascular Medicine. Kathy is a consultant and presenter for the fitness industry and fitness professionals. Got a question? Ask Kathy now.

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Last Updated: October 19, 2002