How Do Doctors Use Height and Weight Charts?
Height and weight charts can be used to determine whether you are the correct weight for your height. These tools are used to monitor:
- childhood growth and development
- weight management
- weight loss
When you go in for a regular checkup, your doctor will likely take your height and weight measurements. The measurements are then used to determine whether you are in a normal weight range for your height, age, and gender.
It’s important to recognize that these tools are used as part of health assessments. No one number fits every individual.
Types of Charts
Doctors use three primary types of charts to measure height and weight.
Head circumference is a growth chart used for children up to 36 months old. During the assessment, a doctor or nurse measures around the widest part of the head. Normal height and weight usually directly correlates with a normal head circumference measurement.
A head that is unusually small for a child’s height may indicate delayed brain development. On the other hand, an unusually large head-to-body ratio may indicate fluid retention on the brain.
Body mass index (BMI), is among the most common height and weight charts used by doctors. Medical professionals use this tool for people as young as age two. The primary purpose is to determine whether you are within a normal weight range for your height, or if you are under or overweight.
According to the Centers for Disease Control and Prevention (CDC), individuals fall into one of the following BMI ranges:
- 18.5 or less: underweight
- 18.5 to 24.9: healthy weight range
- 25.0 to 29.9: overweight
- 30.0 or higher: obese (CDC, 2011)
BMI is calculated using one of the following two formulas, depending on the units of measurement for height and weight:
- pounds and inches: weight (pounds) divided by [height (inches)] squared multiplied by 703
- kilograms and meters: weight (kilograms) divided by [height (meters)] squared
Waist circumference is a chart often used in conjunction with BMI. It is based on the idea that a larger waist can indicate a higher-than-normal weight for your height. According to the CDC, a healthy waistline is less than 35 inches in non-pregnant women and less than 40 inches in men.
Healthy Growth Measurement
Head circumference and height and weight measurements are crucial in monitoring a child’s healthy development. Once your child is measured, your pediatrician will place the numbers on a chart that compares them to the average height and weight for someone your child’s age.
These are called percentiles. The 50th percentile indicates the average height and weight for a given age group. Anything above 50 is considered above average, and anything below 50 is below average.
While percentiles are important for measuring a child’s growth and development, it is important to be realistic. If your child is overweight for his or her height, you must determine whether lifestyle (ex. lack of exercise or unhealthy diet) is a factor.
In contrast, being below average may indicate undernourishment. However, this is rare in the United States. Talk to your doctor about all the factors that can influence height and weight in children.
As you reach your full adult height, the focus of BMI measurements transitions towards weight management. Adults with above-normal BMIs are encouraged to lose weight. The same is true for men and non-pregnant women with large waist measurements. Decreasing your weight by even a small percentage may help decrease your risk of heart disease and Type 2 diabetes.
Doctors pay special attention to children and adults with BMIs in the obese range. Obesity is an epidemic that raises the risk of developing serious health conditions. If exercise and diet do little to reduce your weight, your doctor may suggest weight loss medications or bariatric surgery.
Drawbacks of Height and Weight Charts
Height and weight charts are routine tools used to help diagnose potential health problems. While number ranges can help, there is no one-size-fits-all range for every person. In fact, the CDC points out that a BMI assessment is a screening tool, but it should not be the single test relied upon for any diagnosis.
If you take your measurements at home and are outside of a normal range, it may be helpful to schedule an appointment with your doctor to ensure that no underlying health problems exist.
It’s also important to pay close attention to the evolution of your child’s height and weight. If your child’s measurements consistently reveal wide variations above or below a certain percentile, you may need to follow up with your pediatrician.