DexaFit Seattle

A major cardiology paper used a surprisingly blunt word to describe the origin of 220 minus age: arbitrary.

The familiar formula came from earlier reviews rather than one large, standardized experiment. In a 2001 paper in the Journal of the American College of Cardiology, Tanaka and colleagues traced the equation to 10 studies.

Their team went on to analyze 351 studies involving 18,712 people and proposed an updated age-based equation:

208 - (0.7 x age)

That equation provides a stronger population estimate of maximum heart rate. Cardio zones still need another layer of context because predicted maximum heart rate and ventilatory thresholds describe different physiological landmarks.

Your wearable can capture useful heart-rate data during a workout. A VO2 test watches how breathing and gas exchange change as the intensity rises, which can help place your training zones around observed responses from your body.

If you want a plain-English guide to cardio zones, thresholds, and wearable data, comment CARDIO and I'll send over the guide.

A Japanese pedometer company may deserve a footnote every time your watch celebrates 10,000 steps.

The number became popular in Japan after the 1964 Tokyo Olympics through a pedometer called the manpo-kei, which translates to "10,000-step meter." It was a terrific product name because it was round and easy to remember.

The clinical research on daily steps came later. A 2025 systematic review and dose-response meta-analysis covering 57 studies found meaningful health associations well below 10,000 steps. Compared with 2,000 steps a day, 7,000 was associated with a 47 percent lower risk of all-cause mortality. Several of the outcome curves showed their largest changes before 10,000.

Because most of this evidence is observational, the broader pattern matters more than replacing 10,000 with a different universal target.

If 10,000 gets you walking, it is doing a useful job. A step count simply answers one question: how much did you move? When you want to decide what to train next, measurements such as DEXA, RMR, and VO2 can add information about the body doing the walking.

Send this to the person who has paced the kitchen at 11:58 p.m. to make the number roll over.

Most health plans begin with a solution.

Eat fewer calories. Add more cardio. Lift heavier. Walk ten thousand steps. Sleep eight hours.

Any one of those actions may be useful. The problem is that the recommendation often arrives before the baseline.

We rarely stop to ask which part of the system is actually limiting progress.

DEXA, RMR, and VO2 testing answer different questions.

DEXA shows what your body is made of, including lean mass, fat mass, visceral fat, and bone density.

RMR measures how much energy your body uses at rest under controlled conditions.

VO2 testing measures aerobic capacity and helps identify the intensity landmarks that organize cardio training.

No single result writes the entire plan.

Together, the results can prevent one assumption from controlling it.

Maybe your next priority is building aerobic capacity. Maybe it is protecting lean mass. Maybe it is reviewing a calorie target that was built from an equation.
Maybe the most useful action is simply creating a baseline before you change anything.

You do not need to maximize every number at the same time.

You need to know what to work on next.

To your health,
Joel
DexaFit Seattle

Most body composition assessments hand you a number and send you home. Here's what happens when you run two tests together and read them as a single picture.

DEXA establishes your lean mass baseline, bone density, visceral fat volume, and bilateral symmetry. RMR establishes your precise caloric burn at rest and whether your body is oxidizing fat or carbohydrate as its primary fuel. Together they produce the exact inputs needed to build a MetaboliX Nutrition Plan calibrated to your actual physiology — not population averages, not generic calculators, not an app estimate based on your age and bodyweight.

Most people have had neither test. Almost nobody has had both interpreted together with a nutrition plan built around what the combined picture actually shows. That's exactly what this package delivers.

Swipe through to see what each test reads and what the combination reveals.

Want a practical tool for hitting your protein floor tonight? Comment BLOCKS and I'll send it to your DMs.

Most people find out their Structural Cylinder is failing from a surgeon.

A torn rotator cuff. A hip replacement consult. A bone density scan that comes back worse than expected.

By that point, the system has been misfiring for years.

Grip strength is one of the earliest signals. And almost nobody is tracking it.

Here's the data worth knowing.
The PURE study followed 139,691 adults across 17 countries and published the results in The Lancet. Every 11-pound drop in grip strength was tied to a 16% increase in all-cause mortality risk, a 17% jump in cardiovascular death risk, and a 9% greater stroke risk.

The finding that stopped researchers cold: grip strength outperformed systolic blood pressure as a predictor of death from any cause.

A separate meta-analysis of 42 studies confirmed it. Low grip strength carries a 67% higher risk of early death compared to age-matched peers with strong grips.

The research community is now formally pushing to classify grip strength as a vital sign, alongside heart rate, blood pressure, and respiratory rate.

What actually drives the decline is worth understanding. After 40, neuromuscular power output starts dropping before detectable muscle loss shows up on a DEXA scan. The connections between motor neurons and muscle fibers begin to degrade.
Testosterone, IGF-1, and growth hormone all trend down, pulling muscle protein synthesis with them.

Your grip weakens because the whole Structural Cylinder is losing efficiency, not because you stopped using your hands.

A single measurement tells you almost nothing on its own. What matters is your number relative to age and sex-matched norms, and whether that number is moving in the right direction over time.
That's what the grip assessment gives you. Medical-grade dynamometer, normative comparisons, full report, trend tracking built in. A number that actually means something.

$35 standalone. $25 as an add-on to any existing assessment.

But if you want the full picture, the Structural Insights Report takes it further.
When grip strength data sits alongside your DEXA lean mass, upper limb lean mass segmentation, and Proteus power output, you stop looking at isolated metrics and start reading a system.
Force production cross-referenced against the actual tissue generating it. Power output benchmarked against the structural substrate supporting it. Upper limb lean mass telling you whether a weak grip reflects a strength deficit, a mass deficit, or both. That's a different level of clinical clarity than any single test delivers on its own.

The Structural Insights Report is $179 and draws from any combination of your DEXA body composition data, grip strength, Proteus power output, and KAMS movement assessment.
Two tests make it meaningful. More data makes it sharper. Every additional layer adds cross-referencing that a single test simply cannot produce on its own.

If you've already done any of these assessments with us, you may already have enough to run the report. Reply to this email and I'll check what's in your file and tell you exactly where you stand.

Joel

P.S. The rate of change matters as much as the number itself. Men and women with a measurable decline in grip strength over time carry a 16 to 33% higher mortality risk per kilogram lost per year. One measurement gives you a snapshot. Serial testing gives you a trajectory. Those are very different things.

Two tests. One picture.

Most body composition assessments give you one data point in isolation. A DEXA scan reads the structural foundation — lean mass, bone mineral density, visceral fat volume, bilateral symmetry. An RMR test reads how efficiently your metabolism is running relative to that foundation.

Run together, they describe something neither test shows alone. Whether your resting metabolism is appropriately sized for the lean mass carrying it. Whether your structural profile carries hidden risk that standard screening misses. Whether the variables most likely to drive decline over the next decade are already in motion or still within reach.

Getting both tests interpreted as a unified data set is genuinely rare. The combined picture is where the useful clinical information actually lives.

Want a practical tool for hitting your protein floor tonight?
Comment 𝗕𝗟𝗢𝗖𝗞𝗦 and I'll send it to your DMs.

Two clients. Both came in during the same month.

𝗧𝗵𝗲 𝗳𝗶𝗿𝘀𝘁: DEXA showed solid lean mass, adequate body fat, visceral fat below threshold. His RMR came back 18 percent below predicted for his lean mass. The structural data alone wouldn't have flagged anything urgent. The metabolic read revealed why rushing toward his next goal without a stabilization phase first would have undercut the whole effort — and gave us the precise caloric target to hold during that window.

𝗧𝗵𝗲 𝘀𝗲𝗰𝗼𝗻𝗱: RMR was well-calibrated to her lean mass — metabolically, the numbers looked clean. The DEXA told a different story. Significant bilateral asymmetry pointed toward structural injury risk that no metabolic test would have found. Visceral fat sitting just above the 2-pound clinical threshold despite a lean overall appearance flagged elevated metabolic risk that her RMR hadn't captured and her mirror certainly hadn't shown.

Same two tests, opposite findings, opposite programming priorities.

Without the RMR, the first client skips the stabilization phase his metabolism actually needed. Without the DEXA, the second client's structural risk and hidden visceral fat load go completely undetected. The number that looks fine is rarely the number worth watching. The number that changes the intervention is usually the one you almost didn't run.

Your resting metabolic rate is, in large part, a function of how much lean mass you carry.

Muscle is metabolically expensive tissue. The more of it you maintain, the higher your resting caloric burn at baseline. The less you carry — whether from age, caloric restriction, or a GLP-1 protocol without structural support — the lower your metabolic floor drops with it.

This means the DEXA scan and the RMR test are measuring the same system from two different angles. One reads the structural chassis. The other reads how efficiently that chassis burns fuel at rest. Run them together and you see how the two numbers interact and what's actually driving your metabolic picture. Run them years apart and you get two data points with no meaningful relationship between them.

The combination reveals what neither test shows alone.

GLP-1 medications are producing real weight loss results. Most patients never see what's happening underneath the number on the scale.

Lean mass loss during aggressive caloric restriction isn't exclusive to GLP-1s — but the speed of loss, the appetite suppression that makes hitting protein targets harder, and the sheer number of people now on these medications without structural monitoring makes the downstream cascade worth understanding clearly.

This is what goes unmeasured when lean mass loss isn't tracked — and what a DEXA scan reveals about it.

Want the tool that translates your protein floor into an actual meal tonight? Comment BLOCKS and I'll send it to your DMs.

The protein math for protecting lean mass during a GLP-1 protocol runs 0.8 to 1.4 grams per pound of lean mass.

Most people are calculating from their total body weight. That denominator is wrong, and the gap compounds during a caloric deficit.

The correct number comes from your lean mass. A DEXA scan gives you that number. Once you have it, hitting your protein floor meal by meal is the next problem to solve.

The Sheet Pan Meal Maker does that part. Enter your lean mass and it calculates your personal protein floor, then builds a complete meal around it — protein, veggies, fat, optional carb — calibrated to your physiology, not a population average.

DEXA gives you the target. The app helps you hit it.

Comment BLOCKS below and I'll send it to your DMs.