Many women exercise to reduce body fat. Shedding body fat can be more challenging for women compared to men, primarily because women need a certain amount of body fat for normal reproductive function. If females lose too much body fat, particularly if they’re exercising and restricting calories, levels of sex hormones like estrogen that affect fertility drop. This leads to menstrual cycle changes and changes in fertility or even a complete lack of menstruation. These changes sometimes happen to women athletes, especially runners, who train hard and get down to a very low body fat percentage. The drop in estrogen can lead to other problems such as loss of bone density and an increased risk for osteoporosis.
What Determines Body Fat Percentage Anyway?
Body fat percentage is simply the weight of the total fat you carry on your body divided by total body weight. If you weigh 120 pounds and have 30 pounds of body fat, your body fat percentage would be 30/120 or 25%. There are a number of ways to measure body fat percentage with varying degrees of accuracy including skin-fold calipers, with a bioelectric impedance scale, underwater weighing or with a DEXA scan. DEXA scan and underwater weighing are more accurate than skin-fold measurements and bioelectric impedance scales, but they’re also more expensive and time-consuming.
Women Need a Certain Minimal Amount of Fat for Health
The fat women need to maintain their menstrual cycles, fertility and a baseline level of health is called “essential fat.” The essential fat that women need is between 10% and 13%. When body fat drops below these levels, it can trigger health problems including loss of menstrual periods and fertility and lead to a decrease in bone density and an increased risk for osteoporosis and fractures. So, what’s a “healthy” body percentage for women? Based on the American Council on Exercise between 21% and 31% is considered healthy for women, but this doesn’t take into account age.
The council guidelines consider women in this age range who fall below 21% to be “underfat,” a term that means underweight from a fat standpoint. It’s still common for women athletes to be below 21% body fat, and most female fitness competitors have body fat percentages that are lower than this with no ill effects. On the other hand, when a woman’s body fat percentage falls below 13%, it can trigger physiological changes that lead to bone loss and menstrual cycle changes, especially if a female is restricting calories and spending a lot of energy working out, putting them into a catabolic state.
Ideal Body Fat Percentages Vary with Age
Although 21% to 31% body fat is considered a healthy body fat range for women, it doesn’t distinguish by age. Muscle mass declines with age and body fat increases, so there’s more leeway in what’s considered healthy. Women under the age of 30 would probably be considered most healthy with a body fat percentage in the low 20s, while women in their 40s and 50s would still be healthy if they were at the higher end of this range, in the mid-20s to low 30s. The average body fat for women as a general group is between 26% and 29%.
Body Fat Percentages in Female Athletes
Ever wonder what the average body fat percentages of female athletes are? Long-distance runners average around 17% body fat, swimmers around 18.5%, while volleyball and basketball players are in the 23% range. Female long-distance runners who compete at a national level average around 15% body fat. Tennis players? About 22%.
The Bottom Line?
There is an essential amount of body fat that women need to maintain health and fertility. Once you fall below 13%, most women will be at higher risk for health problems. Once your body fat rises above 31%, your risk for health problems of a different nature starts to rise – the risk for obesity-related problems like heart disease and type 2 diabetes. It’s not a good idea to focus on body fat but measure it periodically to make sure you’re in a healthy range.
References:
ACE Fitness. “What are the guidelines for the percentage of body fat loss?”
Exercise Physiology: Energy, Nutrition and Human Performance. Fifth Edition. 2001.
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What’s the Best Way to Track Your Body Fat Percentage?
What’s a Healthy Body Fat Percentage for Women?
How Effective Are Skin-Fold Measurements for Determining Body Fat Percentage?
A Better Way to Measure Body Fat?
Normal Weight Obesity: Can You Be of Normal Weight and Still Be Obese?
Thank you! Great information!
What I’ve noticed about my InnerScan scale is that body fat readings change based on the program entered… Female and Female Athlete give 2 very different numbers. I don’t really understand why which program matters since it’s supposed to read the amount of body fat. Period.
It almost sounds like changing what you call yourself causes the scale to “make up a number'” based on program entered. It doesn’t sound like it could be accurate. If your body fat is 27, it is that whether you are an athlete or not. Like you, I certainly don’t understand. My scale gives me different readings before and after a shower. I was told the shower changes how the electricity moves through my body. Perhaps these scales just are not very accurate at all. I have always questioned how a woman who is 5′ 7″, exercises regularly, and weighs 129 most days could show that her body fat is 1/3 (33 or 34%) of her most days. Is 43 pounds of me really fat??? There are so many things that are more important than this in life, but this is puzzling! Can someone at cathe.com explain this?
When it comes to measuring body fat with calipers or a scale that measures body fat through electrical impedance you’re not actually measuring body fat, but instead you’re measuring parameters related to body fat. These measurements are then compared to body fat data taken from thousands of test subjects from all walks of life. Some of these people may work out every day while others may not work out at all. Thus, by taking a large sample you end up with an average body fat reading that the measurement from the scale or skin calipers can be compared to determine your estimated body fat percentage. However, if you’re an athlete and work out regularly the measurement from the scale or calipers will not provide an accurate number unless you use it with formulas derived from testing other similar athletes. If you use a formula based on test results with predominately sedentary people for athletes their body fat percentage will have a much higher degree of inaccuracy than if you use a formula based on data and test done on athletes.
Many other things can affect the accuracy of body fat measurements such as temporary water weight gain, how recently you worked out with weights, and inflammation. Though people get hung up with their body fat number, you have to realize there is high degree of inaccuracy in its calculation. You should only use this number as a reference point to see if your body fat is increasing or decreasing with time.
@ CatheDotCom – Thank you, I can understand the parameters related to body fat.
@ Kay – I read about the readings online; if someone has been doing fitness for years then select Athlete — I think that agrees with what CatheDotCom has stated. Works for me 🙂
To Cathe.com, Thank you so much for your explanation of how scales/calipers provide numbers. The reminder that it is important to see if body fat is increasing or decreasing with time is reassuring. Also, to Jennifer, thank you for your comment. It makes perfect sense.