The body mass index is a method you can use to determine if you are at the appropriate weight relative to your height. Your physician can use BMI to determine indicators about your health. Some research studies have linked a woman’s BMI at the time she started her period, which is known as menarche, with an indicator of future bone mineral density as an adult.
BMI Calculation
To calculate your BMI, divide your weight in pounds by your height in inches squared, and then multiply this number by 703, according to the Centers for Disease Control and Prevention. For example, if you weigh 150 pounds and are 5 feet, 5 inches tall, you would divide 150 by 4,225, then divide this number by 703 to get a BMI of 24.96. An underweight BMI would be less than 18.5 while a normal BMI would be between 18.5 and 24.9. Any result between 25.0 and 29.9 is considered overweight while a BMI higher than 30.0 is considered obese. Note, however, that BMI is not infallible as an accurate predictor of overall health because if you are a very active person, you may have more muscle mass, and this will cause you to have a high BMI, yet be healthy.
Tufts University Study
A 2001 study published in “Osteoporosis International” conducted at Tufts University looking at 119 young women in the early 1970s registered them by height, weight and age at menarche. Thirty years later, Tufts University researchers followed up with these same women who were now between the ages of 40 and 45 in 2001. The researchers found that weight at menarche was associated with adult bone mineral density, particularly for women with low bone mineral density. Women who fell in the lowest BMI ranges at menarche had 8 to 15 percent lower average bone masses than women in the highest BMI range at menarche. These findings caused researchers to conclude low BMI at menarche is a risk factor for low bone mineral density in pre-menopausal women.
Cornell University Study
A 2002 study conducted at New York Presbyterian Hospital by researchers at the Weill Medical College of Cornell University published in “Clinical Pediatrics” studied female patients to determine if there was a link between BMI and age of menarche. The researchers found patients with higher BMI were more likely to experience menarche at a younger age. Girls with an obese BMI result were more likely to experience menarche at age 11.87 while girls in the normal BMI range did not undergo menarche on average until age 12.20.
Conclusions
Adolescent weight and age of menarche can potentially have a link to a young woman’s overall health. Because bone mineral density in adulthood is important in preventing bone fractures that can lead to immobility, maintaining a normal BMI is important to adolescent girls as a potential predictor for future health.
References
- "Clinical Pediatrics"; Body Mass Index and Age at Menarche in an Adolescent Clinic Population; Karen Lin-Su, M.D., et al; September 2002
- "Osteoporosis International"; Weight and Body Mass Index at Menarche Are Associated With Premenopausal Bone Mass; 2001
- Centers for Disease Control and Prevention; About BMI for Adults; September 2011
- Go Ask Alice!; What's a Healthy Weight?; March 2009
- MayoClinic.com; Amenorrhea; May 2011
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