Most often people 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 assess and figure a healthy weight.
Gone are the ancient “life insurance tables” from the 50’s, and while it is still tempting to use the “100 lbs for 5 feet plus 5 pound per inch thereafter” (meaning a 5’5” woman would be at a desired weight of 125 pounds), we in the profession use 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 a good place to start. 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 considered overweight; and >30.0 is considered obese.
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 someone who is “obese” by this standard is Dwayne “The Rock” Johnson. He is clearly not obese, but his BMI classifies him that way. However, most people who have a high BMI of overweight or obese are usually not high muscle low body fat percentage. To know for sure, measure your body fat percentage.
Body Composition aka Body Fat Percentage
I refer to this as body composition, but people say “you’re measuring how much fat I have.” This is technically true, but we are also measuring fat-free mass that includes 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. While you can buy skinfold calipers and do it on yourself, I don’t recommend this. It takes skill and experience to do it correctly, and it is better to have high quality calipers, usually about $200. Let an experienced person do this on 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. You have to get your residual lung volume measured the first time. This is the amount of air that is always in your lungs, after you exhale completely. Remember that, since you need to exhale completely when you are underwater. After measuring your lungs, you are weighed while you are completely underwater and have exhaled completely. This method tends to have limited access for many people.
DXA is a method of measuring your entire body, and is mostly used to assess bone density. This is a very accurate method, but expensive and with limited access.
BodPod is a method of measuring body fat using air displacement, like the hydrostatic weighing, but with air instead of water. Claustrophobics should avoid this one, since it requires the person to sit in an enclosed, egg-shaped capsule for several minutes.
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 is able to calculate how much body fat you have. There are several types of BIA: 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 that measure body fat use this method, as does the Omron Body Logic, which is a hand-held device.
The Omron is portable, and something you can have in your home for about $50 or less. You enter your information (height, weight, age, gender and “normal”) and it a few seconds it gives your body fat percentage as well as your BMI.
This is the method I recommend for people if they want to monitor their body fat percentage on their own. Since it is affordable, easy and does not need skill.
There are many standards for body fat percentage. It varies based on age and gender mostly, but there are different standards for a limited amount of ethnicities and athletes depending on the sport. I tell people to pay attention more to how personal number changes rather than the standards. For example, if you are a 40-year-old woman with a 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 obese.
So stop depending on the scale so much and use some of these other methods to assess your healthy body weight.