InBody Segmental Lean Analysis: Comparing Your Left and Right Sides
The segmental lean analysis on an InBody sheet splits your lean mass into five parts: right arm, left arm, trunk, right leg and left leg. Each is shown in kilograms and as a bar against a standard for your height and weight. It lets you see whether one side carries noticeably more lean mass than the other, and whether your upper and lower body are in proportion. Small differences are normal, particularly between a dominant and non-dominant arm. Larger or growing gaps are worth a look, and usually respond to sensible one-sided training.
Here is how to read the section, what deserves attention, and what to do about it.
What the section shows
The InBody passes its current through the body along several paths, using electrodes at both hands and both feet. That lets it estimate each limb and the trunk separately, rather than the body as one block. On most result sheets you will see:
- Lean mass in kilograms for each of the five segments.
- A bar or percentage showing how each segment compares with a standard for someone of your height and weight. Around 100% means about average for your frame.
- On some models, a matching segmental fat analysis showing fat mass in each region.
“Lean mass” here includes muscle, water and other non-fat tissue in that region, not muscle alone. That matters when you interpret small changes. Our guide on reading InBody results line by line covers the rest of the sheet.
How to read left against right
Compare the two arms with each other and the two legs with each other, in kilograms. A few points help put the numbers in context:
- Expect your dominant side to be a little larger. Years of carrying bags, writing, throwing and opening doors on one side add up. A slight difference between arms is normal.
- Arms differ more readily than legs. They are smaller, so a small absolute difference shows as a bigger proportional gap.
- Look at the trend. A gap that is stable over several scans is less interesting than one that is widening.
- Check conditions. Posture on the machine, how you hold the handles and recent training of one side can all nudge a single reading.
Rather than chasing a precise threshold, ask: is the difference large enough that you can also see or feel it? A visibly smaller calf, a shoulder that tires first, a leg that always fails earlier on split squats. When the scan and your training agree, the imbalance is real.
Upper body versus lower body
The bars also show proportion. A common pattern in desk-bound professionals is upper body segments around or above the standard and legs below it, often because people skip lower body work or did more upper body training in the past. The reverse appears in runners and cyclists who never lift. Neither is a problem in itself, but it guides where training time should go.
Common causes of a left-right gap
- Handedness and daily habits. Always carrying a laptop bag on the same shoulder, always holding a child on one hip.
- Sport. Tennis, golf, cricket and racket sports load one side more.
- Past injury. A knee or ankle injury often leaves the affected leg smaller, sometimes years later, because people unconsciously favour the other side.
- Training with only barbells and machines. Bilateral exercises let the stronger side quietly do more of the work.
What to do about it
The principle is simple: give each side its own work, so the weaker side cannot hide.
Add unilateral exercises
Single-arm and single-leg movements are the core tool. In a studio with a dumbbell rack and a cable station, that might include:
| Area | Useful one-sided exercises |
|---|---|
| Legs | Split squats, reverse lunges, step-ups, single-leg Romanian deadlifts |
| Upper push | Single-arm dumbbell press, single-arm cable press |
| Upper pull | Single-arm dumbbell row, single-arm cable row or pulldown |
| Arms | Single-arm curls and cable extensions |
Let the weaker side set the pace
Start each set with the weaker side, choose the weight and reps it can manage with good form, then match those exactly on the stronger side. Do not do extra reps on the strong side.
Consider a little extra volume
For a clear gap, one additional set for the weaker side can help, provided recovery is good. Keep it modest.
Keep the big lifts
Squats, deadlifts, presses and rows remain the backbone of strength. One-sided work supports them; it does not replace them. Our piece on muscle imbalances discusses when an imbalance matters and when it is simply normal human asymmetry.
When to get it checked
A sudden or large difference that you cannot explain, or one that comes with pain, numbness, weakness that is getting worse, or swelling, is not a training question. Check with your GP first. The same applies if the gap follows an injury or operation that has not been rehabilitated. A physiotherapist may need to be involved before strength training.
The scanner itself is not suitable for anyone with a pacemaker or other implanted electronic device, and the result is not meaningful during pregnancy.
How often to re-check
Muscle changes slowly. A re-test every six to eight weeks, under the same conditions (morning, before eating or training, same clothing), is enough to see whether a gap is closing. Pair the scan with a simple performance check: the weight and reps you can manage for split squats or single-arm rows on each side. If both are moving towards each other, the plan is working.
How it is used in the studio
In the private studio on Archway Road, the InBody is in the room where you train. With Artem, a segmental reading is one of the things used to shape a programme: where one side lags, sessions include more one-sided work, and the gap is checked again a few weeks later. You can read more about private personal training in Highgate and the equipment available.
Questions we get asked
Is it normal for my right arm to be bigger than my left?
Yes, if you are right-handed. A slight difference is expected and rarely matters.
My legs show below 100%. Should I worry?
Not necessarily. It suggests the legs are less developed than average for your frame, which is common and responds well to regular lower body training.
Can imbalances cause injury?
Large ones may contribute, especially after a previous injury. Small, everyday asymmetries are normal. If you have pain, see your GP or a physiotherapist.
How quickly can I even out a gap?
Expect months rather than weeks. Consistent one-sided work is what closes it.
For the recommended weekly baseline of strength work, see the NHS physical activity guidelines for adults. Find out more about the studio at The Highgate House or on the personal trainer page.
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