--- type: Article title: "How to Read an InBody Printout" description: "The four numbers on an InBody result sheet worth reading, how FFMI is worked out from them, and how to make two scans comparable." resource: https://quietgains.app/journal/reading-an-inbody-printout tags: ["body composition", "inbody", "ffmi"] timestamp: 2026-09-22 --- # How to read an InBody printout Four lines on the sheet hold the numbers everything else is built from. What each one reports, and what it does not. Body composition · By [QuietGains](https://quietgains.app/about) · Published 22 September 2026 · Updated 22 September 2026 · 3 min An InBody sheet is a bioelectrical impedance result: the device passes a small current through the body and estimates its composition from the reading. The sheet prints segmental readings, phase angle and a score out of a hundred. Four lines hold the numbers the rest are built on. | Number | What it tells you | | --- | --- | | Weight | The baseline everything else is divided by | | Body fat mass | How many kilos of the total are estimated to be fat | | Skeletal muscle mass | The estimated weight of the muscle attached to the skeleton | | Body fat percentage | Fat mass as a share of weight | From those you can work out two figures the sheet often buries: lean mass, which is weight minus fat mass, and FFMI, which is lean mass adjusted for height. ## What FFMI adds Bodyweight says nothing about how much of it is lean. Fat-free mass index divides lean mass in kilograms by height in metres squared, so two people of different heights can be compared. Kouri and colleagues added a small correction that normalises the value to a height of 1.8 m [1]. In their sample of 157 male athletes, the normalised FFMI of those who had not used anabolic steroids extended up to a well-defined limit of 25.0 [1]. > The ESPEN guideline on impedance asks for follow-up measurements at the same time of day, under standardised conditions. ## How to make two scans comparable The European Society for Clinical Nutrition and Metabolism lists the conditions that change an impedance reading [2]. - Same device and the same time of day for every follow-up; each device applies its own prediction equation [2]. - Fasted: the guideline names fed or fasting state as what affects results most [2]. - Bladder voided before the measurement [2]. - No exercise beforehand: straight after exercise resistance fell by about 3 per cent and reactance by about 8 per cent, back to normal an hour later [2]. The sheet prints numbers whatever the conditions were. A scan taken fed, or straight after training, is not the same measurement as one taken under the standard conditions, and the two should not be read as a change. ## Reading the trend Two scans make a line; three start a trend. Because the sheet lists fat mass and skeletal muscle mass separately, a change in weight between scans can be split into the part that is fat and the part that is not. The ESPEN guideline notes that follow-up by impedance is possible in people without abnormal hydration, but must be interpreted with caution [2]. QuietGains keeps each scan in a [body composition history](https://quietgains.app/#body-composition). ## What the score out of a hundred is for The score is the manufacturer’s own summary figure, not a measurement. None of the sources below describe it, so this piece reads the four lines it sits beside instead. Related tool: Type weight and fat mass off your sheet, with your height, into the FFMI calculator and it works out body fat percentage, lean mass and FFMI, with every step shown. [Open the calculator](https://quietgains.app/tools/ffmi-calculator) ## Sources 1. Kouri EM, Pope HG Jr, Katz DL, Oliva P. Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clinical Journal of Sport Medicine 5(4):223-228, 1995. https://doi.org/10.1097/00042752-199510000-00003 2. Kyle UG, Bosaeus I, De Lorenzo AD, et al. (ESPEN). Bioelectrical impedance analysis, part II: utilization in clinical practice. Clinical Nutrition 23(6):1430-1453, 2004. https://doi.org/10.1016/j.clnu.2004.09.012 ## Read next - [Progressive overload without a spreadsheet](https://quietgains.app/journal/progressive-overload) - [Protein per kilo, not per cent](https://quietgains.app/journal/protein-per-kilo) - [How long to rest between sets](https://quietgains.app/journal/rest-between-sets)