More Than a Number on the Scale: Measuring Healthy Weight

People often use the number on the scale to assess their weight and have a number in mind for their healthy weight. But there is more than just weight that helps evaluate and figure a healthy weight.

Gone are the ancient “life insurance tables” from the ’50s, and while it is still tempting to use the “100 lbs. for 5 feet plus 5 pounds per inch after that” (meaning a 5’5” woman would be at the desired weight of 125 pounds) when working with healthy, or mostly healthy, people we must consider several other factors to assess healthy weight.

Body Mass Index (BMI)

While this isn’t the gold standard by any means, this ratio of height to weight is an excellent place to start. You are using your real height and weight plug those numbers into the tool here. 

Desired BMI is 18.5- 24.9; 25.0 – 29.9 is classified as overweight; and >30.0 is classified as having obesity.

There are some drawbacks to this measure: it does not take into account body fat percentage. So, you could be muscular and be overweight or obese using BMI. An example of those who are “obese” by this standard are people like Dwayne Johnson or Arnold Schwarzenegger during his bodybuilding and early acting year. Neither would be considered over-fat, but BMI classifies people like this in that way. However, most people who have a high BMI of overweight or obese are usually not high muscle-low fat percentage. To know for sure, measure your body fat percentage.

Body Composition aka Body Fat Percentage

Referred to as body composition, but people say, “you measure how much fat I have.” This is technically true, but we also measure fat-free mass, including muscle, organs, bone, and other non-fat tissue.

There are several ways to assess body fat percentage: skinfold (pinch test), hydrostatic, DXA, BodPod, and BIA. Some are more accurate than others; some you can conduct on yourself.

Skinfold is what many clients refer to as the one “where you pinch my fat.” Yes, it is. It measures the fat under your skin known as subcutaneous fat. While you can buy skinfold calipers and do it yourself, this isn’t recommended. It takes skill and experience to do it correctly, and it is better to have high-quality calipers, usually about $200 or more. Let an experienced person do this for you.

Hydrostatic, aka underwater, weighing takes several steps to complete and again is not a do-it-yourself method. Hydrostatic testing is considered the “gold standard” but requires patience and access to this method, which isn’t widely available. Many people refer to this as the “dunk tank.” The first time it is done, you do have to get an extra step to have your residual lung volume measured. This is the amount of air that is always in your lungs even after you exhale completely. To complete the underwater weighing, you need to go underwater. Not everyone is comfortable with this. Nor are they comfortable with the next step of submerging themselves completely underwater AND exhaling as much air from their lungs as possible. It is natural to hold your breath when going underwater, so that part takes some practice. While you are underwater and having exhaled as much as possible, your weight is measured. With this many steps and limited access, this method is not available to most people.

DXA is a method of measuring your entire body and is mostly used to assess bone density. It is a specialized type of x-ray, a very accurate method, but expensive and with limited access. It is most often used for research purposes.

BodPod® measures body fat using air displacement, as the hydrostatic weighing, but with air instead of water. Like the hydrostatic weighing, lung capacity is measured prior to the first test. This one is relatively easy since all you need to do is sit inside the enclosed pod. However, it is a small space, so persons with claustrophobia should avoid this one since it requires the person to sit in an enclosed, egg-shaped capsule for several minutes. Also, if someone is big, they may not fit inside including those who are very tall. It is much smaller than a SmartCar.

BIA, aka bio-electrical impedance, measures how fast electricity goes through your body. Since electricity flows faster through water than fat, and muscle is nearly 70% water, it can calculate how much body fat you have. There are several BIA types: the best will measure from your ankle to your wrist with electrodes attached to each. However, most people don’t have access to this. Scales measure body fat using this method and may have electrodes on the footpads as well as something to hold. Some scales have just the footpads, while there are some portable handheld devices.

With the BIA, you enter your information (height, weight, age, and sex) and in a few seconds, it gives your body fat percentage and BMI. 

BIA at home is the method I recommend for people if they want to monitor their body fat percentage independently since it is affordable, comfortable, and does not need skill.

There are many standards for body fat percentage. It varies based on age and sex mostly, but there are different standards for a limited number of ethnicities and athletes depending on the sport. I encourage people to pay attention more to how their personal number changes rather than the standards. For example, if you are a 40-year-old woman with 42% body fat, I recommend you work on getting that to 40%, then 35%, and so forth and not focusing on whether you are average or in another classification.

Stop depending on the scale as your ultimate and use another method to assess your healthy body weight if you have access to one.