What your report says, in plain language — and where the numbers come from.
Under construction
We are still building this page out. Everything on it is accurate — there is just more coming.
The paper in your hand
What is on your report
There is an enormous amount of body-composition content on the web and most of it is guessing dressed up as measurement. This page is the opposite. It explains the four pages you take home before you leave.
Your test measures three things: what you weigh on land, what you weigh underwater and how warm the water is. Your height, age and gender come from your record. Every number printed on the report is worked out from those.
How the numbers are made
What is measured and what is worked out
The tank measures three things. Everything else is arithmetic. That is true of every body composition test there is and we would rather say so than call the whole report “measured.”
What you weigh, in and out of the waterMeasured
The three things the tank actually reads: what you weigh on land, what you weigh underwater and how warm the water is, which we keep at 89–92°F. Your height, age and gender come from your record. You go under three times — the report averages all three when they agree closely and the two heaviest when they do not.
Air left in your lungs makes a dunk read light and a light dunk reads body fat too high. That is why the heaviest dunks are the ones that count.
Air left in your lungsEstimated
Even when you blow out all the air you possibly can, some air always remains in your lungs. We use your height and age to estimate that remaining air and account for it in your body fat % calculation.
Treat about a point of difference between tests as noise. The trend across several tests is the real signal.
Body fat percentageWorked out
Muscle sinks and fat floats. So the gap between what you weigh on land and what you weigh underwater tells us how dense you are and how dense you are tells us how much of you is fat. The water temperature and the air in your lungs are both part of that sum.
It moves over weeks, not days. If it jumps overnight, that is noise, not fat.
Lean massWorked out
Everything that is not fat: muscle, water, bone, organs. It is not a muscle measurement, though muscle is the part of it you can change.
This is the number to protect. Lean mass dropping while the scale drops is the outcome you are testing to avoid.
RMR- The amount of fuel required for basic function at restEstimated
Using your lean mass weight, we calculate using the Cunningham formula to measure your RMR. This is specific to holding still awake on your back and reflects about 70% of your caloric requirement in the day.
An estimate, not a calorie prescription. It moves when your lean mass moves.
Worth reading
A short list, on purpose
Sources we actually open. Each one earns its place.
