PBF
Percent Body Fat (PBF)
Percent Body Fat tells you what share of your total weight is made up of estimated fat mass.
Short answer
Percent Body Fat is a share, not a weight of fat. It moves with both fat and muscle, so never read it on its own and base decisions on several comparable measurements rather than one visit.
- Fat share18.4 %
- Rest of body weight81.6 %
What the value represents
Percent Body Fat is a share, not an amount. Fat mass in kilograms is divided by total weight and expressed as a percentage. The manual uses a worked example: 12 kg of fat at a body weight of 50 kg gives 24 %.
Because it is a ratio, it can move for two different reasons. It falls when you lose fat, but it also falls when you gain lean tissue and fat stays where it was. That is exactly why the percentage and fat mass in kilograms do not always move together.
The number is not measured directly. InBody measures the electrical properties of your tissues, estimates total body water and fat free mass from them, and treats fat mass as the remainder of your weight. How trustworthy the estimate is therefore depends on how closely your hydration on the day matches the assumptions the method is built on.
- The share of your total body weight that is fat mass, expressed as a percentage.
- It covers every kind of fat the method estimates: subcutaneous fat, fat inside the abdominal cavity, and essential fat that forms part of cell membranes, nerve tissue and organs.
- It says nothing about where that fat sits. Two people with identical percentages can have very different distribution, and therefore a very different picture.
How the value is produced
- A calculated value. The formula is body fat mass (kg) ÷ weight (kg) × 100.
- Fat mass is itself an estimate: multi-frequency bioelectrical impedance gives total body water, total body water gives fat free mass, and fat is the difference between measured weight and estimated fat free mass.
- Weight is the only directly measured quantity in the whole calculation.
How to read the current value
- The manufacturer manual uses 15 % for adult men and 23 % for adult women as the reference value. That is the midpoint the device works from, not a target you have to reach.
- The recommended range in the manual is 10–20 % for men and 18–28 % for women. The manufacturer labels 20–25 % for men and 28–33 % for women as slightly raised, and above 25 % for men or 33 % for women as raised.
- Below the age of 18 the reference is derived from the average height for that age, because body composition changes throughout growth.
- The range printed on your result sheet is a manufacturer reference, not a health threshold. Athletes, older adults and people with a different build can sit outside it without that meaning anything on its own.
How to read change over time
- Compare measurements taken under comparable conditions: similar time of day, similar fluid intake, and no training or sauna immediately beforehand.
- A difference of a few tenths of a percent between two visits is not a reliable signal. What carries meaning is the trend across several measurements weeks apart.
- When the percentage falls, check that fat mass in kilograms fell too and that muscle mass held or grew. A percentage that drops while muscle disappears is a very different situation from one that drops with muscle intact.
- When the percentage rises, look at weight and at fat in kilograms first. A rising share with unchanged fat mass means something else was lost, typically muscle or water.
General principles: how to read change between measurements →
What to read it with
- Body Fat Mass (BFM) – the absolute amount that the percentage alone hides.
- Skeletal Muscle Mass (SMM) – tells you whether the share moved because of fat or because of muscle.
- Weight – without it a change in the ratio cannot be read correctly.
- Visceral Fat Area (VFA) – adds the distribution information that a whole-body percentage does not carry.
- BMI – together they expose the case where weight looks ordinary but the fat share is high.
Common misunderstandings
- Percent Body Fat is not the number of kilograms of fat. The same percentage in two people of different weight means a different amount of fat.
- Lower is not automatically better. Very low body fat carries its own risks, and the body needs fat for basic functions.
- The value is not a grade for your health and not a diagnosis of obesity. A manufacturer range is not a medical threshold.
- It cannot tell you where the fat is stored. That is what visceral fat and circumference measures are for.
- A change of a few tenths of a percent between two visits usually reflects the conditions of the measurement rather than a real change in body composition.
What can affect the result short term
- Food and drink shortly before the measurement, which raise weight and shift the composition estimate.
- Hydration status, including dehydration after training or a sauna.
- Training shortly before the measurement, which redistributes fluid in the body.
- Alcohol the day before, illness, fever and room temperature.
- Time of day: water moves towards the lower half of the body as the day goes on.
- The menstrual cycle, during which fluid retention varies.
- A full bladder, heavy clothing or jewellery.
What to do next
The explanation of the value is the same for everyone. Only the suggested step changes — pick whichever fits you.
- Always read the percentage together with fat mass in kilograms and with muscle mass. Only the three together make sense.
- If you are tracking fat loss, fix your measurement routine and repeat it after four to eight weeks, not after a few days.
- When body composition is the goal, watch whether fat falls while muscle holds. That is the difference between losing weight and losing muscle.
- If the number worries you, discuss it with someone who can also see your health context rather than acting on a single figure from a single visit.
What the value does not determine
- It does not determine health status and does not diagnose obesity.
- It cannot separate subcutaneous from visceral fat.
- It cannot tell whether a shift came from a real change in fat or from a change in hydration.
- It is not a reference method for clinically establishing the amount of body fat.
On terminology
- The manufacturer speaks of a recommended range rather than a normal value. The range is a reference, not a health norm.
When to discuss it with a professional
If the result worries you or differs sharply from your previous measurements, discuss it with a doctor or another qualified professional. The measurement itself is not a diagnostic tool.
In more depth, with sourcesIn more depth: why percent body fat depends on hydration and fat free massExpand the detailed explanation
Bioelectrical impedance analysis does not measure fat. It measures the resistance and reactance that tissues present to an alternating current at several frequencies. Those quantities are used to estimate total body water, and from water to fat free mass, because water makes up roughly 73 % of fat free mass. Fat mass appears as the difference between measured weight and estimated fat free mass, and the percentage is a step further downstream again.
That chain is where the uncertainty comes from. If your hydration on the day departs from the assumed proportion, the estimate of fat free mass shifts and the calculated fat shifts with it. The NIH consensus statement on bioimpedance therefore treats standardised measurement conditions as a precondition for comparing repeated results, and the ESPEN clinical guidelines name altered fluid distribution as a situation in which body composition estimates from bioimpedance become less dependable.
The practical consequence is simple. A single value carries limited information, while a series taken under the same conditions is usable for following a trend. The manufacturer does not claim absolute agreement with reference methods such as DEXA; the device is built for repeated monitoring, not for establishing a diagnosis.
Sources
- InBody 970 Result Sheet Interpretation (ENG_A_211104) — InBody Co., Ltd.
- Bioelectrical impedance analysis in body composition measurement: NIH Technology Assessment Conference Statement — National Institutes of Health
- Bioelectrical impedance analysis – part II: utilization in clinical practice — Clinical Nutrition (ESPEN guidelines)
- Obesity and overweight — World Health Organization
On this page
Related values
Commonly confused with
Related articles
Where to find it
The Muscle-Fat Analysis bar chart and the Obesity Analysis section that follows it.
- Reviewed by
- MojeInBody content team
- Date
An InBody measurement is not a diagnostic tool. Results do not determine health status and do not replace a medical examination.
FAQ
Frequently asked questions
Answers to what people ask most often about this value.
Why is my body fat percentage different on another scale or device?
Different devices use different equations, a different number of frequencies and a different kind of contact with the body, so values are not interchangeable between them. Comparison only makes sense between measurements from the same type of device taken under similar conditions.
My percentage went down but my fat in kilograms stayed the same. How?
The share also falls when fat free mass increases and fat stays where it was. Check muscle mass and weight — if both went up, this is exactly that case.
What body fat percentage should I have?
The manufacturer manual works with a reference value of 15 % for men and 23 % for women, and a recommended range of 10–20 % for men and 18–28 % for women. What is actually appropriate for you depends on age, sex, training history and health context, none of which the device knows.
Does menstruation affect the result?
Yes. Fluid retention varies across the cycle, which feeds into the estimate of fat free mass and therefore into percent body fat. For tracking a trend it helps to measure at a comparable point in the cycle.
Explanations make the most sense alongside your own trend.
The public guide is open to everyone. The client portal adds your own value, history and the context of a specific measurement.