The Only Two InBody Numbers Worth Reading at First
A body composition printout has twenty-plus values. For your first few months, two of them decide everything: skeletal muscle mass and body fat percentage.
An InBody printout gives you twenty-plus values — segmental lean mass, segmental fat, total body water, mineral content, phase angle, visceral fat level.
Two of them matter at the start: skeletal muscle mass and body fat percentage.
Why only two
Body weight alone has no direction. When 2kg comes off you cannot tell whether it was fat, muscle or water. Reading skeletal muscle and body fat together resolves that.
- Body fat down, muscle held: this is working
- Body fat down, muscle down: you are cutting too fast — raise protein and keep lifting
- Body fat flat, muscle up: weight unchanged is still a win
The remaining values do not change that call. Segmental lean mass becomes useful for spotting left-right imbalance, but only after several measurements.
People only fill in two anyway
We looked at what RebelUp users entered.
Nobody has completed the segmental fields. Even holding the printout, people do not transcribe twenty values.
So RebelUp asks for two first. Asking for eight makes most people abandon the form entirely.
How often to measure
Every 8-12 weeks is enough. Monthly is fine, but readings swing 1-2% with hydration, meal timing and time of day, so short intervals cannot be separated from measurement error.
- Morning, fasted, after the bathroom
- Avoid measuring right after training — dehydration inflates body fat percentage
- Use the same machine. Different devices give different numbers