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Why these, not just weight
Weight tells you one thing: the total mass of your body, including muscle, fat, water, bone, and whatever’s in your stomach.
That’s why two people with the same weight can look completely different. And why the scale can move in the wrong direction even when you’re getting healthier — losing fat while gaining muscle often shows as ‘no change’ on a regular scale.
The metrics below show what’s actually happening underneath. Use them in the order they appear in your email — that’s the order they matter.
The Big Three
These are the three numbers most worth watching. They appear at the top of your post-scan email for a reason — they tell you the story of what’s actually changing in your body.
Weight
What it is
Your total body weight in kilograms.
What it tells you
Direction of total mass — but not what’s making up that mass. Useful in context with the next two metrics.
What’s a good number
Depends entirely on your goal. Going up while lean muscle is going up = building. Going down while body fat is going down = leaning out. Going down while lean muscle is also going down = a problem worth talking to your coach about.
Lean Muscle Mass
What it is
Everything in your body that isn’t fat. Muscle, bone, organs, water, connective tissue.
What it tells you
Whether you’re holding onto — or building — the tissue that drives your metabolism, strength, posture, and long-term health.
What’s a good number
Trending up or holding steady. After 30, lean mass tends to decline by around 3–8% per decade if you don’t train. Holding it steady is a win. Building it is a bigger win.
Body Fat
What it is
Your total fat mass in kilograms — both the visible kind under your skin and the kind around your organs (more on that below).
What it tells you
Direction of fat change in absolute terms. Often easier to interpret than body fat percentage because it’s not affected by changes in muscle mass.
What’s a good number
Trending in line with your goal. For most members the goal is gradual reduction while lean mass holds or increases.
Additional Metrics
These metrics give you more context for what’s happening underneath the headline numbers.
Body Fat %
What it is
Body fat as a percentage of total weight.
What it tells you
Body fat in proportion to your total mass. Moves when fat changes OR when lean mass changes — so it can shift even if your fat in kg hasn’t moved.
Men
| Category | Range |
|---|---|
| Athletic | 6–13% |
| Fitness | 14–17% |
| Average | 18–24% |
| Above average | 25%+ |
Women
| Category | Range |
|---|---|
| Athletic | 14–20% |
| Fitness | 21–24% |
| Average | 25–31% |
| Above average | 32%+ |
Ranges are general guides. Your coach will interpret your number in the context of your age, training history, and goals.
Skeletal Muscle Mass
What it is
Specifically the muscles attached to your bones — the ones you train. A subset of total lean mass.
What it tells you
Whether your training is doing what it’s meant to: building or maintaining the tissue you use to move, lift, and stay strong.
What’s a good number
Trending up over months or holding steady year on year. This is the metric to look at if you want to know whether your training is working.
Total Body Water
What it is
All the water in your body — inside cells, between cells, and in your bloodstream. Measured in litres.
What it tells you
Hydration status, broadly. Big swings between scans usually mean a hydration shift, not a real body composition change.
What’s a good number
Stable, scan to scan. Roughly 50–65% of your total weight depending on body composition. Changes here are usually about consistency of pre-scan conditions, not a problem with your body.
Visceral Fat
What it is
Fat stored deep in your abdomen, around your organs. Different from the fat under your skin — and far more important for long-term health.
What it tells you
This is the metric that matters most for cardiovascular and metabolic risk. High visceral fat is linked to insulin resistance, type 2 diabetes, and heart disease — independent of how you look from the outside.
What’s a good number
| Category | Range (kg) |
|---|---|
| Optimal | under 1.0 kg |
| Elevated | 1.0–1.5 kg |
| High | above 1.5 kg |
A lean person can still have high visceral fat. A heavier person can have low visceral fat. This is one of the most important reasons we scan — you can’t see this number from the outside, and it’s often the most life-extending number on your scan to move in the right direction.
Reductions of 100–200 grams in visceral fat between scans are meaningful. This is a slow-moving metric — don’t expect dramatic week-to-week change.
Bio Age
What it is
An estimate of your body’s biological age based on your composition — muscle mass, body fat, hydration.
What it tells you
Whether your internal health is tracking ahead of, behind, or in line with your chronological age.
What’s a good number
Lower than your actual age, trending downward. A Bio Age 5 years younger than your real age is a good signal that your training and lifestyle are working.
Caveat
This is a directional metric, not a medical prediction. Don’t treat it as a death clock. Treat it as a thumbs-up or a nudge.
Bio Age also depends on accurate profile data. If your height, age, or activity level aren’t up to date in the Evolt Active app, the Bio Age figure can read strangely. If something looks off, check your profile first.
Bio Wellness Index (BWI)
What it is
Evolt’s proprietary score combining your muscle mass, body fat, and visceral fat into a single number out of 10.
What it tells you
Overall body composition health in one figure — much more useful than BMI, which only looks at height and weight and can label muscular people as ‘overweight’.
What’s a good number
| Score | Interpretation |
|---|---|
| Below 5.0 | Significant room for improvement |
| 5.0–6.9 | Average |
| 7.0–8.4 | Good |
| 8.5+ | Excellent |
We use BWI instead of BMI for a reason — BMI was designed in the 1830s and doesn’t know the difference between fat and muscle. BWI does.
A 0.5 point gain on the BWI is meaningful. Aiming to move from a 7.2 to an 8.0 over six months is a strong, realistic goal.
How to read your trend
Single scans tell you very little. Trends tell you almost everything.
Look for direction over three or more scans, not week-to-week wobble. A scan that comes back ‘worse’ than the last one isn’t a problem if the three before it were trending the right way.
The metrics in your post-scan email are designed to be read together, not in isolation. Lean mass up + body fat down = winning, even if total weight barely moved. Total weight down + lean mass also down = worth a conversation with your coach.
Your full progress chart in the SOF App shows trends over time. That’s where the real story is.
A note on accuracy
BIA technology — the kind the Evolt 360 uses — is highly repeatable when conditions are consistent. Evolt’s published repeatability sits at 98–99%, which rivals DEXA for tracking change over time.
But repeatability depends entirely on you scanning under the same conditions each time. That’s why the pre-scan guide matters. Two scans done under different conditions can show a 1–2kg swing in lean mass that’s purely about hydration, not about your body actually changing.
The scan is a tool. Like any tool, it’s only as accurate as the way you use it.
About reference ranges
The reference ranges on this page are general population guides drawn from Evolt’s published documentation and standard body composition science. They aren’t medical diagnostics, and they don’t account for your specific age, training history, ethnicity, or health context.
Your coach interprets your numbers in the context of you. If anything in your scan looks off, message your coach in the app — that’s what we’re here for.
The Evolt 360 isn’t a diagnostic tool. If you have specific health concerns, talk to your GP.