Body Mass Index bmi for women, female version
This post will be challenging some rather old-fashioned ideas surrounding body mass index bmi for women.Traditionally the BMI chart for women is linear, however, this model is not an ideal or a true representation of the changes in a healthy weight for women according to age.
As most of us are aware by now, body mass index (BMI) has been a traditional way of measuring how healthy your body weight is in relation to your height. To calculate Body Mass Index you divide your weight in kilograms by your height squared in metres.
Chart for Body Mass Index BMI for Women
The chart below shows more curved lines that indicate how a woman’s body mass index changes with age. Quite interesting, really. I bet you haven’t seen this chart anywhere else!
Notice the “median” (or average) weight bmi value, which is the 50th percentile Red line.
Traditional Criteria for Body Mass Index for Women
Compare the chart above to the Centers for Disease Control and Prevention (CDC) definitions of overweight according to BMI as below:-
- A BMI of less than 18.5 falls in the underweight range
- Body Mass Index of 18.5 to 25 is within the normal range
- If your BMI is between 25 and 30 then it falls within the overweight range according to the CDC criteria
- A BMI of 30 or over falls within the obese range
According to the above definitions, a healthy bmi for women is between 18.5 and 25. However, a woman with a body mass index of over 25 is in the overweight or obese categories. In other words, this is above the ideal body weight range.
Thus, this is how the experts came up with the famous, and often quoted, statistic that over 50 percent of American Women are considered overweight based on having a BMI of over 25.
However, these classifications do not take into account the age of women.
Comparison of the Nhanes III survey and the CDC criteria for Body Mass Index BMI for Women
Notice in the Nhanes III body mass index chart above, there is a gradual increase in the body mass index bmi for women over time. Furthermore, the BMI gently increases until the age of 50 to 60.
However, after age 50 to 60 a gradual decrease in BMI occurs in older women.
Interestingly, each percentile line has a curved shape, even for the very slim women (or those classed as a normal weight or even underweight) at the 25th and 10th percentiles.
BMI charts for children
The BMI chart shows how for girls, the BMI increases with age, even after age 20.
The children’s data came from the standard CDC growth charts.
There is a gap between the children’s and adult data, because the data sources are different.
The adult data (from the NHANES III survey) is more recent ( 1988-1994 ), whereas the body-mass-index-for-age charts from the CDC are based from a mix of data from old and recent sources.
BMI charts for Men
Our page contents also show a body mass index chart for men (below).
Comparing man and woman BMI charts, you will notice some differences.
For men under the 50th percentile the BMI is higher than for women. This is thought to be because men have a greater skeletal muscle mass.
However, after age 30, for the 50th percentiles or higher, overweight women have higher BMI values than men.
Why is that?
Probably because body fat percentage is also an important factor if a woman is going to be overweight.
Indeed, BMI for women fails to take into account the full body composition. A woman’s body accumulates more fat in the breasts and hips, which are places that men’s fat accumulation doesn’t occur. This is why waist-to-hip ratio is also important.
This female trait probably explains the higher BMI in overweight women.
I realize that the charts can be a little hard to read, so the table below shows the actual numbers:
|The “National Average” Median Body Mass Index values for Women are:|
|Age:||20-29 yrs||30-39 yrs||40-49 yrs||50-59 yrs||60-69 yrs|
Surf onward to:
- Return to the Body Mass Index calculator for women,
- Or to the mens BMI calculator,
- Or see the Men’s BMI chart, (similar to this page)
January 29,2015 update. If you are over age 50, you REALLY ought to see this page, proving that having a BMI of 25 to 30 is actually the healthiest and reduces risk of death. This range of BMI is not actually overweight.
Questions and Answers
How to use BMI?
BMI is used as a screening tool that is a weight to height ratio to identify weight problems for adults. These include identifying if a person is underweight overweight and obese.
However, body mass index is not a diagnostic tool.
In addition, a healthcare provider may perform further assessments if your bmi is outside of the ‘normal’ range.
These assessments may include:-
- Evaluation of diet
- If necessary, advice on a healthy weight loss plan
- Assessment of physical activity, and again, a healthy exercise plan
- Medical family history
- Possibly other health screenings such as testing for type diabetes or high cholesterol levels
- Waist circumference measurements or waist-to-height ratio to find out if you are carrying too much belly fat which can be a health risk
Why use BMI to measure overweight and obesity?
Are there any other ways to measure obesity?
Other methods used to measure obesity include:-
- Skinfold thickness measurement calipers
- Underwater weighing
- Bioelectrical impedance
- Dual-energy x-ray absorptiometry (DXA)
- Isotope dilution
However these methods are not always readily available because they are expensive or need highly trained personnel.
How reliable is BMI as an indicator of body fatness?
What is a healthy BMI?
As we have seen, BMI does vary according to age, gender and race, but the general guideline for a healthy bmi is between 20 and 25
What does your BMI mean?
To have a BMI under 18.5 is considered very underweight and possibly malnourished. However, a BMI of 18.5 to 24.9 is within a healthy weight range for young and middle-aged adults. Furthermore, a BMI between 25.0 and 29.9 is classed as overweight. Finally, a BMI over 30 is considered obese.
Are there any exceptions to the rule?
The BMI measurement can not differentiate between body fat and muscle mass. Hence, there are some exceptions to the BMI guidelines, for example, if you have a large frame size or are very muscular.
What are the health consequences of overweight and obesity for adults?
- Hypertension or high blood pressure
- Dyslipidemia (Cholesterol problems)
- Type 2 diabetes
- Coronary Heart Disease
- Gallbladder Disease
- Sleep Apnea
- Respiratory Problems
- Some cancers including endometrial cancer, breast cancer, and colon cancer.
Is BMI interpreted the same way for children and teens as it is for adults?
Yes, but the criteria used to interpret BMI numbers for children and teens is different from those used for adults.
Finally, for children and teens, BMI age, and gender-specific percentiles are used for two basic reasons:
- The amount of body fat changes with age
- Also, the amount of body fat differs between boys and girls