In the lab, we never do an experiment without first figuring out how we are going to measure and track our results. If you are trying to change your body composition, you need to identify the right tools for tracking it. There are a lot of tools that we can use to track changes in body composition and so we need to look at those that are most appropriate for us and where we are on the fitness spectrum.
According to my BMI, I am still overweight. Although BMI really can’t be used accurately with strength athletes or body builders, BMI is still a pretty good tool and it works really well with beginner exercisers and/or deconditioned people. It just doesn’t really apply very well once you start building in an appreciable amount of muscle. But if you are new to the gym, figuring out your BMI will give you a good idea as to where you are starting from
The scale is another good tool, but must be taken with a grain of salt. Muscle weighs more than fat so when using scale weight as a tracking tool, you have to consider where are you are relative to where you want to be. There are no exact numbers. For example, at 5’7″ and 160 lbs, I am leaner than some who weigh less than me. And getting back to what you weighed in high school does not guarantee you the same body.
DEXA scans are great because they not only tell you how much body fat you have, but how much lean body mass, and how dense your bones are which is pretty important once we start getting older. Other methods for measuring bodyfat are okay but tend to have larger margins of error.
One of the simplest measurements that I still track regularly is my waist circumference. Certain waist sizes are associated with higher health risks and so regardless of how big and strong you are you want to make sure that waist measurement doesn’t get too high or you are at higher risk for heart disease and diabetes. Generally speaking, women should keep it under 35 inches and men under 40 inches.
Finally simply taking a selfie in the mirror in just your underwear or a bathing suit on a regular basis can tell you what changes are going on in your body over time even though it might not be reflected on the scale.
Personally, I think it’s good to use a couple different tools to keep track of your body composition. Sometimes when the scale weight isn’t changing, my waist circumference or body fat percentage may both be going down. And photos don’t lie unless you involve photoshop and some filters. Whether you are trying to put on mass, lose some fat, or staying a certain weight class, keeping track of where you are with a couple different methods is your best bet for being able to see where you are and make the changes you need to make to get where you’re going.