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What Your Scale Won’t Tell You: The Ultimate Truth About Body Fat.

November 18, 2024

What if I told you that you aren’t as lean as you think?

That’s not an insult: It’s just the likely reality—if you’ve gotten your body fat percentage from a high-tech digital scale or even skinfold calipers. 

While both methods can give you a solid baseline number to monitor, they tend to lack the precision to capture your true body composition. 

And, chances are, it’s a few points higher than you think. 

In this article, I’ll show you why, and reveal the gold-standard test for measuring body fat. 

But just in case you don’t find that interesting enough…

I’ll share new scientific data showing the average age males and females reach their highest levels of body fat, and when they’re most likely to begin losing muscle and bone mass. (Teaser: Here are some important ages the researchers highlighted—31, 32, 47, 55, 62, 75, 81.)

And, as a bonus, I also dug up the REAL body fat percentages of NCAA Division 1 athletes, bikini competitors, and NFL players. (The numbers will probably surprise you.)

The Truth About Body Fat Measurements

First, know this: If you have a body fat measurement from a digital scale, skinfolds, or even an online calculator, it can be very useful. 

Although it’s unlikely to be the most accurate assessment, it allows you to track general trends over time. That’s the most important thing. 

Why? Because it gives you an indicator of how well your diet and lifestyle are working for you. 

Not going the direction you want? Time to make some changes. 

That said, if you want “the truth,” a dual X-ray absorptiometry scan, or DEXA scan, is the way to go. 

What Exactly Is a DEXA Scan?

A DEXA scan is a non-invasive test that uses low-level X-rays to measure body composition. 

To put the radiation exposure into perspective, it’s about the same amount you’d naturally absorb from spending a day outside in the sun—or from a short flight at high altitude. 

This minimal exposure makes DEXA scans safe for periodic use if you’re monitoring changes over time.

Besides being the gold standard for assessing your body composition, it offers two bonuses: It’s good at measuring both visceral fat and bone density.

That’s important because… 

Visceral Fat and Bone Mass REALLY Matter for Longevity

You probably know this, but visceral fat is the kind of deep belly fat that surrounds your vital organs—and it’s linked to an increased risk of metabolic disease.¹ 

Subcutaneous fat, on the other hand, is the fat that’s just under your skin, which is thought to be relatively harmless. 

DEXA can differentiate between these two kinds of fat, but here’s some insider knowledge: While many people think DEXA directly measures visceral fat, that’s not accurate. 

DEXA actually estimates visceral fat by analyzing the fat and lean mass in your body, and applying specialized algorithms to predict how much visceral fat you likely have. (Studies show these estimates are reliable.)

When it comes to bone density, DEXA is one of the most accurate tools available, measuring how much mineral content is packed into your bones.

This can help you spot early signs of bone loss or osteoporosis—a condition that affects 1 in 5 women over 50—and take action to address it.

Where Can You Get a DEXA Scan?

You’ve heard of Google, right? Just kidding. 

But you will need to search for a place near you. That’ll likely be a medical imaging center, sports performance center, or wellness facility. The cost tends to range from around $100 to $200. 

For the appointment, you’re generally asked to wear comfortable clothing without any metal parts, such as zippers or buttons (metal can interfere with the scan’s accuracy). 

During the procedure itself, you’ll essentially lie down on a padded bench while a robotic arm scans your body from head to toe. Unlike an MRI, it’s an open setup, so you won’t feel enclosed.

The scan itself usually takes about 20 minutes to complete.

What About Bod Pods?

If you just want an estimate of your body fat percentage, the Bod Pod—or air-displacement plethysmography—is my second favorite choice.  

In case you’re curious, here’s my stack ranking of popular body composition tests: 

1. DEXA

2A. Hydrostatic Weighing (this was the gold standard before DEA, but it’s not particularly pleasant or convenient as it requires you to blow air out of your lungs... underwater in large tank... while sitting on a cadaver scale)

2B. Bod Pod (way more available than hydrostatic weighing, and you don’t have to sit on a cadaver scale underwater)

3. Skinfold Measurements (make sure you go to the same technician each time as it’s how you’ll get the most consistent measurements)

4. Bioelectrical Impedance (this is the method that high-tech digital scales use: an unnoticeable electric current shoots through your body, but your hydration status can make your body fat percentage read higher or lower on any given day)

Okay, now for some fun. Let’s take a look at those numbers I promised you at the beginning of this article.  

How Your Body Fat, Muscle, and Bone Change with Age

In a 2024 study, researchers in France used DEXA scans to analyze the fat mass, lean mass, and bone mineral density of 915 participants, aged 20 to 93 years old.² 

The scientists were looking for what they call “break points.”

Break points are the specific age when substantial changes in fat mass, lean mass, or bone density begin to occur. Here’s what they found:

Fat Mass Break Points

• Males: Fat mass increases sharply in their 20s, then slows down around age 32. In other words, they tend to pack on fat fast and then maintain that size for years.
  
  
• Females: Fat mass increases gradually with age until around age 75, after which it begins to decline. This decline is likely a sign of increased frailty.

Lean Mass Break Points

(In the case of DEXA*, the measure of lean mass includes muscle, tendons, ligaments, and water, but you can consider it a good proxy for muscle itself.)

• Males: Lean mass remains stable until about age 55, then starts to decrease.
  
  
• Females: Lean mass begins decreasing around age 31. 

Bone Density Break Points

• Males: Bone density remains stable until around age 59, then declines.
  
  
• Females: Bone density has two distinct break points:
• Stable until age 47.
• Rapid decrease from age 47 to 62.
• Stabilizes between ages 62 and 82.
• After age 82, a downward trend in bone mass resumes. (Again, a likely indicator of increased frailty.)

What can you do with this information? 

Knowing the average break points can help you gauge where you are in the cycle now. 

The more muscle and bone you add while you can, the more in reserve you’ll have as you age. It’s like building equity in your body.

What if you’re already in the “down” years? Hopefully, it motivates you to take action (if you aren’t already).

Regardless, the advice is the same: The best way to increase and maintain both muscle and bone density is resistance training. 

The second best way? Stay active, period. Yoga, hiking, daily walks, skiing, and yes, pickleball. Whatever you love, or can consistently tolerate, do it.

Use it or lose it? It’s never not been good advice. (That’s a horrible double negative, but you get the point.)

Why Most Body Fat Percentages Are “Wrong”

Ever hear a guy say he’s 3 percent body fat? It’s probably not true.

For one, that’s actually a dangerously low level of body fat for a male. Anything below 5 percent is considered essential fat—the minimum amount needed for vital bodily functions.

For women, the cutoff is about 12 percent. Their body fat is naturally higher because it supports reproductive health and hormonal balance. 

But here’s another reason you might question that number: It’s probably not a DEXA measurement.  

Remember how I said most people aren’t as lean as they think? 

Popular methods like bioelectrical impedance often underestimate body fat compared to DEXA.

An example: When scientists measured competitive volleyball players (mostly female), skinfolds and bioelectrical impedance estimated their body fat at around 18 percent, but DEXA showed them closer to 24 percent.³

This isn’t always such a discrepancy, but when you look at DEXA scans of elite athletes, you start to get a better idea of what truly low body fat percentages look like—and they’re rarely as low as people believe.

What Do “Real” Body Fat Percentages Look Like?

Popular culture often gives the impression that “ultra-low” body fat is both common and sustainable, especially for athletes and fitness enthusiasts. But in reality, achieving and maintaining very low body fat levels is rare—and can be tough on the body.

In one study, researchers used DEXA scans to measure body fat in 27 female fitness and bikini competitors before they began their 20-week training for a competition and again on the morning after the event.⁴ Here’s what they found:

• Body fat before competition training: 23%
• Body fat after the event: 12.7%

Yes, 12.7 percent is exceptionally low, but that’s likely why they didn’t stay there for long. Four months later, their average body fat had returned to 20.1 percent. (They were still very fit.)

Now, let’s consider the body fat levels of elite athletes, as measured by DEXA. Knowing how lean these athletes look, you might be surprised at some of their actual body fat percentages. 

Female Division I Athletes⁵

Male Division I Track & Field Athletes⁶

NFL Players⁷

What Can You Take Away from All This?

1. If you can afford and access a DEXA scan, I recommend an annual scan—since it not only measures body composition but bone mineral density (which too often isn’t given enough attention). 

This provides important information that can help you identify opportunities to maximize your health span. 

2. If you can’t get a DEXA, find another way to track your body fat—whether it’s a Bod Pod, a skin caliper technician, or a good digital scale that uses bioelectrical impedance. But make sure to stick to the same method for monitoring purposes. 

Using a different approach (or a different technician) is likely to give you inconsistent results that make it harder to track changes accurately over time.

3. Focus less on the number itself, and more on what you can do to improve and optimize it. Your body fat percentage doesn’t define you as a person, but knowing where you stand, no matter what the number is, can help you make informed choices to improve your health over time. 

Remember, it’s about using the information as a tool—not a label—to guide you toward better well-being.

References 

5. Dobrosielski DA, Leppert KM, Knuth ND, Wilder JN, Kovacs L, Lisman PJ. Body composition values of NCAA Division 1 female athletes derived from dual-energy X-ray absorptiometry. J Strength Cond Res. 2021 Oct 1;35(10):2886–93.

6. Dengel DR, Keller KA, Stanforth PR, Oliver JM, Carbuhn A, Bosch TA. Body composition and bone mineral density of Division 1 collegiate track and field athletes, a Consortium of College Athlete Research (C-CAR) study. J Clin Densitom. 2020 Apr;23(2):303–13.

7. Dengel DR, Bosch TA, Burruss TP, Fielding KA, Engel BE, Weir NL, et al. Body composition and bone mineral density of national football league players. J Strength Cond Res. 2014 Jan;28(1):1–6.