Weight, Fat and Muscle Control (WC, FC, MC)
These three figures in kilograms show how much the device model would have weight, fat mass and fat free mass change to reach its calculated target weight.
Short answer
The three numbers tell you how far your body composition sits from the device reference model, and in what ratio between fat and fat free mass. That is a useful breakdown, but it is not a plan — a plan comes from your context, not from one measurement.
What the value represents
The Weight Control section contains four values. The first is Target Weight; the other three are differences against your current state: Weight Control (WC), Fat Control (FC) and Muscle Control (MC). All are in kilograms.
The sign gives the direction. A positive number is a suggestion to add, a negative one to reduce. The typical combination has fat control negative and muscle control positive — the model is describing a rearrangement of weight rather than simply lowering it.
This is exactly why these three values must not be read as a plan. The device does not know whether you have medical constraints, how you train, what you eat, whether you are recovering from illness, or whether losing weight is appropriate for you at all. It is a calculation from one measurement against a reference model, not a decision about what you should do.
Their usefulness lies mainly in the breakdown. Lose three kilos on its own says nothing about what those three kilos should come from. Splitting it into a fat and a fat free component is information an ordinary scale cannot give.
- Weight Control (WC) — the difference between current weight and Target Weight in kilograms.
- Fat Control (FC) — by how many kilograms the model would have fat mass change.
- Muscle Control (MC) — the suggested change in the fat free component in kilograms. Behind this item sits the FFM Control output, that is a change in fat free mass; alongside muscle that includes water, organs and minerals, so it is not a pure skeletal muscle target.
- It does not represent a rate of change or a time frame. None of the values says how long a change should take.
- It does not represent a treatment or training plan.
How the value is produced
- Calculated values. They arise as the difference between the current state and Target Weight, which the device derives from its model of balanced body composition.
- The inputs are the bioimpedance body composition estimate and the directly measured weight. The manual gives no equation for Target Weight or for the individual adjustments.
- Weight Control is the sum of Fat Control and the fat free mass adjustment, so the three numbers hold together as a single balance.
- This is a comparison against a reference model, not a measured quantity. The manual describes ideal and target values as references rather than individual goals.
How to read the current value
- Read the sign and the magnitude together. Small values close to zero mean your current state does not depart much from the model; large values mean a larger deviation from the reference, not urgency.
- A negative fat control with a positive muscle control is a common combination. The model is describing a rearrangement of composition, not plain weight loss.
- When weight control is close to zero while fat and muscle control carry large values with opposite signs, the model considers your weight fine but your composition different from the reference.
- Do not take the values as a commitment. They are reference figures calculated from one measurement, not a recommended course of action.
- The example values in the manual (weight control −15.8 kg, fat control −17.3 kg, muscle control +1.5 kg, for instance) are illustrative data from a demonstration sheet and are not norms of any kind.
How to read change over time
- Because all three values derive from Target Weight, they change even when only body composition changed and weight stayed the same.
- A shrinking negative fat control between comparable measurements is a sign that the fat component is moving closer to the model. Confirm it against fat mass in kilograms, though, which is easier to read.
- When muscle control falls towards zero, fat free mass is approaching the reference. If it grows instead, either fat free mass was lost or Target Weight shifted.
- Differences between two measurements a few days apart mostly reflect measurement conditions. Only a comparison weeks apart under the same conditions carries meaning.
General principles: how to read change between measurements →
What to read it with
- Target Weight — the reference point all three adjustments derive from.
- Body fat mass in kilograms — the absolute value behind fat control, which can be followed directly.
- Skeletal muscle mass — more specific than muscle control, because it excludes water and minerals.
- Fat free mass — the quantity muscle control actually corresponds to.
- InBody Score — according to the manual it follows from the values in this section, so it moves along with them.
Common misunderstandings
- This is not a plan or a prescription. The model does not know your health context and therefore cannot recommend what any particular person should do.
- Muscle control is not a target for skeletal muscle mass. It is a change in fat free mass, which also contains water, organs and minerals.
- A negative weight control does not mean your current weight is medically problematic. It is a deviation from a model, not a diagnosis.
- The values carry no time frame. Nothing states how long a change should take, and the device claims nothing about it.
- A change in the values between measurements need not mean progress or deterioration. They build on a body composition estimate that is sensitive to measurement conditions.
What can affect the result short term
- Food and drink shortly before the measurement, because they change both weight and the composition estimate.
- Hydration status, including dehydration after training or a sauna.
- Training shortly before the measurement, which changes fluid distribution.
- Time of day and the menstrual cycle.
- The accuracy of the entered height, age and sex, which the reference values derive from.
What to do next
The explanation of the value is the same for everyone. Only the suggested step changes — pick whichever fits you.
- Use the trio as a breakdown, not as an assignment. The most valuable information is the ratio between fat and muscle control, not the absolute numbers.
- For following development, reach instead for fat mass in kilograms and skeletal muscle mass — both are read directly and do not depend on the manufacturer model.
- When setting your own goal, frame it as a change in body composition over a specific period rather than reaching a number from the device.
- If the values imply a large change in weight, discuss the approach with someone who knows your health context.
What the value does not determine
- They are not an individual treatment, dietary or training plan.
- They do not establish a time frame or a rate of change.
- Muscle control concerns fat free mass as a whole, not skeletal muscle alone.
- The manufacturer model is not published, so the values cannot be recalculated or verified.
- They carry the uncertainty of the bioimpedance body composition estimate, including sensitivity to hydration.
On terminology
- A positive number is a suggestion to add, a negative one to reduce. The sign says nothing about urgency.
- Muscle Control is the user-facing name for the FFM Control output, that is the suggested change in fat free mass.
- The manufacturer speaks of reference and recommended values, not of a norm.
When to discuss it with a professional
If the values imply a substantial change in weight, or you are dealing with illness, pregnancy, an eating disorder or medication that affects weight, discuss the approach with a doctor or another qualified professional. The device does not know that context.
In more depth, with sourcesIn more depth: what in this section is calculation, what is model, and where its limits lieExpand the detailed explanation
The whole Weight Control section rests on a single derived point — Target Weight. The manual states that it is not based on height and ideal weight but on balanced body composition for maintaining a healthy weight, and does not publish the equation. All three adjustments are therefore differences against a non-public model, not separately measured or independently verifiable quantities.
The model takes in the bioimpedance estimate of fat and fat free mass. That estimate is sensitive to the distribution of body fluids: the ESPEN clinical guidelines on bioimpedance warn that in states with altered water balance the fat free mass estimate shifts. Because muscle control corresponds precisely to a change in fat free mass, that uncertainty feeds into the Weight Control section directly rather than at one remove.
One final limitation follows from the manufacturer terminology rules. InBody describes ideal and target values as references rather than individual recommendations, and in charts uses Under / Normal / Over in the sense of a device reference range rather than a medical norm. Any reading that turns these kilograms into a health goal goes beyond what the documentation claims.
Sources
- InBody 970 Result Sheet Interpretation (ENG_A_211104) — InBody Co., Ltd.
- InBody Brand & terminology guidelines — InBody USA
- Bioelectrical impedance analysis – part II: utilization in clinical practice — Clinical Nutrition (ESPEN guidelines)
On this page
Related values
Related articles
Where to find it
The Weight Control section below the Muscle-Fat Analysis.
- 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.
My fat control says −8 kg. Do I have to lose eight kilos?
No. It is the difference between your fat mass and the value the device model works with. It is not a recommendation, it has no time frame and it accounts for nothing in your health context. What you do about it is your decision, and where relevant your professional advisor.
Why is my fat control negative and my muscle control positive at the same time?
That is a common combination. The model is describing a rearrangement of body composition — less fat and more fat free mass — rather than plain weight loss. This is also why weight control can be far smaller than fat control.
Does muscle control mean I should gain exactly that many kilograms of muscle?
Not exactly. It is a suggested change in fat free mass, which alongside muscle includes water, organs and minerals. For following muscle itself, skeletal muscle mass is the more specific value.
The values changed markedly between measurements without me doing anything differently. Why?
The whole section builds on a body composition estimate that is sensitive to hydration, food, training and time of day. If the measurement conditions differed, the estimate shifts and all four values shift with it. Compare only measurements taken under similar conditions.
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.