When weight comes off quickly, the scale tells you how much your weight has changed. It does not tell you how your body composition has changed.
Tracking Percent Body Fat, Body Fat Mass and Skeletal Muscle Mass alongside weight can provide additional context. These are estimates, so focus on trends measured with the same device under consistent conditions rather than treating a single reading as proof of fat loss or muscle preservation.
The GLP-1 research discussed below looks beyond weight to examine changes in body composition. In the published semaglutide study, researchers assessed Body Fat Mass and Skeletal Muscle Mass separately, illustrating why a change on the scale does not describe every component of weight loss. Source: Rodríguez Jiménez et al., 2024.
InBody analysed 38,331 body composition measurement records from people in Korea using GLP-1 weight-management medication. This was a count of measurement records, not 38,331 individual participants.
The reported average changes over 16 weeks were:
| Reported change | Women | Men |
|---|---|---|
| Weight reduction | 7.06 kg | 8.36 kg |
| Reduction relative to starting weight | 9.5% | 8.5% |
| Body Fat Mass reduction | 4.9 kg | 6.0 kg |
| Skeletal Muscle Mass reduction | 1.3 kg | 1.4 kg |
Calculated from these rounded group averages, Body Fat Mass accounted for approximately 69% of the weight reduction in women and 72% in men. Skeletal Muscle Mass accounted for approximately 18% and 17%, respectively. These two components do not account for the entire weight change.
Changes in Skeletal Muscle Mass were particularly noticeable within the first four weeks after the first measurement and became more gradual afterwards. Individual results varied, and some users gained muscle.
These findings describe the analysed records. They do not establish how much muscle any individual will lose or predict outcomes for everyone losing weight quickly.
Source: Financial News coverage of InBody’s analysis, 30 July 2026.
A separate retrospective study followed 88 adults with obesity and type 2 diabetes for 24 weeks: 55 received injectable semaglutide and 33 received oral semaglutide. Body composition was assessed using an InBody 770.
Table 2 reports Body Fat Mass reductions of 8.5 kg in the injectable group and 8.0 kg in the oral group. Fat-free mass decreased by 1.7 kg and 0.6 kg, respectively; the oral-group change was not statistically significant.
The study also reported Skeletal Muscle Mass separately, with reductions of 1.1 kg in the injectable group and 0.5 kg in the oral group. Again, the oral-group change was not statistically significant.
Fat-free mass and Skeletal Muscle Mass are different measurements and should not be used interchangeably. The study had no untreated control group, so its findings should not be presented as proof that medication alone caused the observed changes.
Source: Rodríguez Jiménez et al., Frontiers in Endocrinology, 2024.
This is a study of semaglutide, a GLP-1 receptor agonist. The GLP-1 findings discussed here relate to the study population and measurement methods; they do not establish that a home scale can assess treatment effectiveness or that every person will experience the same changes. Source: Rodríguez Jiménez et al., 2024.
Weight shows the overall change. It is useful, but it does not identify which body components have changed.
Body Fat Mass expresses the estimated amount of fat in kilograms. Percent Body Fat expresses fat as a proportion of total weight.
Read them together. A lower body fat percentage does not, by itself, prove that muscle has been preserved. Likewise, an unchanged body fat percentage does not mean that no fat has been lost.
For example, at 30% body fat, a person weighing 80 kg has 24 kg of fat. At the same percentage and a weight of 76 kg, that figure is 22.8 kg. The percentage is unchanged, but the amount is lower. This is a mathematical illustration, not an individual measurement or prediction.
Skeletal Muscle Mass provides an estimate of the muscle attached to your skeleton. Following its trend alongside weight and Body Fat Mass can help you see changes that weight alone does not show.
A stable reading is not a guarantee that no muscle has been lost. If a downward trend persists or you have concerns about rapid weight change, discuss the results with a healthcare professional.
The InBody Dial H40 also provides Leg Muscle Level, an additional result focused on leg muscle. This adds another point of reference alongside the overall Skeletal Muscle Mass result. Source: InBody Dial H40 product page.
Record Leg Muscle Level and Skeletal Muscle Mass as separate results. A level should not be interpreted as kilograms of muscle gained or lost, or as a direct measure of leg strength. Compare the same result over time under consistent testing conditions, rather than using a single level to conclude that muscle has been preserved. If the readings raise concerns, discuss them with a healthcare professional.
These results provide additional context, but they do not divide weight loss into fat and muscle.
Basal Metabolic Rate concerns resting energy needs. It should not be treated as a second measure of muscle loss.
Visceral Fat Level is a level-based result. It is not the same measurement as the visceral fat area reported in square centimetres in the semaglutide study.
Use the same device and follow its testing instructions. InBody Europe recommends consistent testing conditions, including a similar time of day, before eating or exercising, after using the restroom, and on a hard, level floor.
A weekly check can be a practical routine. However, the studies discussed here do not establish once-weekly measurement as the best frequency for everyone.
Compare several readings over time rather than drawing conclusions from a single increase or decrease. If you are receiving treatment, follow your healthcare professional’s advice about monitoring.
Source: InBody Europe FAQ.
The InBody Dial H20, H30 and H40 all use electrodes at the hands and feet. They provide core results including Weight, Body Fat Mass, Percent Body Fat and Skeletal Muscle Mass.
The models also differ in connectivity and additional results.
InBody Dial H20
The H20 connects to the InBody App through Bluetooth. You enter your height using the dial before testing. It is an option for someone who wants core body composition results and is comfortable using their phone as part of the routine.
InBody Dial H30
The H30 adds automatic user recognition and Wi-Fi syncing. Its product page states that results can sync to the user’s app profile even when the phone is in another room.
InBody Dial H40
Building on the features of the H20 and H30, the H40 adds Leg Muscle Level for additional insight into leg muscle.
Choose according to the results you want to follow and the measurement routine that suits you.
The InBody Dial is a wellness device, not a medical device. This article is for general information and does not replace advice from a healthcare professional.
Sources: InBody Dial H20, InBody Dial H30, InBody Dial H40, and model comparison.
Last reviewed: 16 September 2026.
InBody makes three home body composition scales: the Dial H20, H30 and H40. All three read at the hands and the feet, not the feet alone. If wellness is becoming part of your everyday, the H20. If sport is already part of your week, the H30. If fitness runs in your household, the H40.
