Planet Fitness has earned its share of outrage online over the years, primarily for the club’s commitment to a “judgment-free zone” philosophy. At various times in the franchise’s existence, deadlifts have been banned, lifters who grunt too loudly have been censored with what’s known as a “lunk alarm,” and trainees have been encouraged to conclude their workouts by ordering slices of pizza.

A gym for all is a good idea, but watch out for those who don’t training normally has inevitably drawn the ire of those who do it frequently (ten years ago, men’s health named Planet Fitness “America’s Worst Gym”). One of the biggest gripes is Planet Fitness’s refusal to put scales in its locker rooms. Of America’s biggest studios – 24 Hour Fitness, Crunch, Equinox – Planet Fitness is the only one where visitors can’t weigh themselves before or after a workout.

I’ll refrain from sounding the lunk alarm, but know this: Planet Fitness is right to avoid the scales. Scales don’t matter. Understanding what your weight is, of course, is helpful, but using a scale as the definitive barometer of one’s well-being or fitness gains is outdated behavior.

When you step on a typical scale, you are not isolating fat from water muscle, you are weighing everything; and because very few of us are disciplined or observant enough to weigh ourselves at the exact same time of day, after exactly the same type of workout or food intake, it’s foolish to put too much emphasis on the number on the screen. It could very well be different an hour or two later.

I distinctly remember some of the later stages of the early seasons of The biggest loser, when the competition was reduced to four or five competitors, and someone stepped on the scale, only to have lost three pounds. The coaches groaned. How could Jack lose so little, after all the hard work he put in in the weight room this week?

Well, at some point, after weeks of fat reduction, the body relearns how to gain muscle, which is denser than fat. (You’ve probably heard the myth that muscle “weighs more than fat,” but the truth is, a pound of muscle actually takes up less space than a pound of fat.) strength training and interval training high intensity, losing a few pounds of fat tends to coincide with gaining a few pounds.

How are we supposed to measure our fitness, then, if not by standing on a scale? In the age of body positivity, are there still quantifiable “home metrics” that signal when someone is out of shape or making progress?

Shift your focus from weight and BMI to visceral fat, also known as belly fat or “hidden fat.” It’s one of the few effective surface-level indicators of less-than-stellar health, and it tends to affect men at a much higher rate than pre-menopausal women. According to the Mayo Clinic, visceral fat predicts a higher risk of cardiovascular disease, type 2 diabetes, colorectal cancer, and sleep apnea.

Why is visceral fat so dangerous? Well, the stuff likes to wrap around your vital organs. Visceral fat burrows deeper than the fat you’re used to, just under the skin (called subcutaneous fat, which you can pinch out with your fingers); it’s stored around the stomach, liver, and intestines, where it increases insulin resistance, raises blood pressure, and contributes to the paunchy “beer gut” that so many men develop as they age.

Technically, you can go to a clinic and shell out for an expensive imaging test to determine the exact amount of visceral fat in your body. But that would be a colossal waste of time. There is an easier solution: take a soft measuring tape from a drawer and find the narrowest part of your belly. It should be above the hips and below the ribs, usually about half an inch above your belly button. Next, measure your waistline.

Doctors classify any male waistline of 40 inches or more as an “unhealthy concentration” of abdominal fat. Ideally, you will fall under this. In case you haven’t, the good news is that visceral fat is extremely sensitive to lifestyle changes. Welcoming constant movement into your life will get you back on track, and turning to a diet rich in natural ingredients—leafy greens, whole grains, vegetables, nuts, beans, berries, lean poultry, and fish—will send fat visceral packaging.

It’s easier said than done, of course, but make these changes little by little and let your waistline be a benchmark for at least one crucial sign of well-being. Notice how a week without beer or processed foods affects the metrics, or a month spent walking half an hour every day helps. Ideally, you’ll want to measure in the morning, right after you wake up, before you’ve even had a glass of water. This shouldn’t be something to obsess over every day, as we like to automatically weigh ourselves upon entering a bathroom or locker room. But check your waistline (and by extension, your visceral fat) every couple of weeks or so, and take note of where the number is headed.

If you want to formalize the process even more, consider an “abdominal fat scan,” a still imperfect, but convenient and accessible option for assessing body composition. I recently tried the Bello2, an Indiegogo darling that’s about the size of a paperweight. The machine connects via Bluetooth to an app on your phone and uses near-infrared wavelength technology to measure tissue absorption in the body. In other words: you hold the thing against your arms, legs and belly until it calculates your body fat percentage and ranks you in a metabolic heatmap, with a range of designations. (I was really hoping for a “Perfect” score, but got “Skinny Abs” instead.)

Bello even spits out a score for visceral fat, expressed as VIS-FL which is measured against the average “of a group of the same sex and age group as the user”. For those looking for a little more precision than a tailor’s tape, you could do worse than having constant access to both your body fat percentage and real-time access to the amount of buried visceral fat. under your abdominal muscles. Plus, like any good health app, Bello offers tips and journals for learning and sticking to healthy routines.

Ultimately, while monitoring belly fat is a smarter route than stepping on a scale every day, avoid letting it take on the inflated importance we’ve long reserved for body weight. Think about bone health, heart rate variability, cortisol production, skin temperature, respiratory rate, sleep efficiency, and more. These biometric data often intersect and affect each other, but they are part of a complex and fluctuating web that includes your ever-changing well-being.

It may sound intimidating, but it shouldn’t be. It’s a reminder that one number will never tell the whole story. No metric should have all this power. The key is to identify which ones, like visceral fat, are worth a little more of your time and attention.