# DEXA vs InBody: Which Scan Tracks Muscle on a GLP-1? **By TelosRX Editorial Team** ยท 2026-10-06 **DEXA vs InBody comes down to precision versus convenience. DEXA uses low-dose X-rays to map fat, muscle and bone. InBody uses a mild electrical current to estimate them. On a [TelosRX](https://telosrx.com) GLP-1 plan, both can track muscle.** The scale tells you what you weigh. It says nothing about what you lost. On a GLP-1 medication, that gap matters a lot. This guide compares DEXA vs InBody side by side. You'll see how each works, how accurate each is and which one fits your goals. ## DEXA vs InBody at a Glance Here's the head-to-head. Skim the table first, then read the sections that matter to you. Factor DEXA (DXA) Scan InBody (Bioimpedance) How it works Two low-dose X-ray beams pass through the body A small electrical current flows through the body What it measures Fat, lean tissue and bone, by region Estimates fat, lean mass and body water Precision High; widely used as a research reference Moderate; best for trends under fixed conditions Hydration sensitivity Low High Visceral fat Estimated from the scan image Estimated by equation Bone data Yes No Radiation Very low dose None Time per scan About 10 minutes About 1 minute Access Clinics, imaging centers, some gyms Many gyms, clinics and wellness studios Best use on a GLP-1 Baseline and checkpoint scans Frequent trend checks between DEXA scans **Short version:** DEXA is the sharper tool. InBody is the handier one. Many people use both. ## Why Body Composition Matters on a GLP-1 GLP-1 medications reduce appetite. You eat less, and you lose weight. But not all of that weight is fat. **Some of it is lean mass.** Lean mass includes muscle, organs and water. A [2026 meta-analysis of randomized trials](https://pubmed.ncbi.nlm.nih.gov/41877354/) found lean mass made up roughly 25% to 39% of total weight lost with incretin medications. That isn't automatically bad. Larger bodies carry extra lean tissue to support the extra weight. Some lean loss is expected. The goal is to keep it as small as you reasonably can. You can't manage what you don't measure. That's where body composition scans come in. They show whether your plan is trimming fat or eating into muscle. For practical ways to protect muscle, see our guide to [protecting muscle while losing weight on a GLP-1](https://www.telosrx.com/blogs/glp1/glp1-muscle-preservation). ## How a DEXA Scan Works DEXA stands for dual-energy X-ray absorptiometry. It's the same core technology used for bone density tests. You lie still on a padded table. A scanning arm passes over you. Two X-ray beams at different energy levels pass through your body. Fat, lean tissue and bone absorb those beams differently. Software turns those differences into a map of your body. - **Regional detail:** arms, legs, trunk, left versus right. - **Lean mass:** muscle plus organs and water, minus bone. - **Visceral fat estimate:** fat packed around your organs. - **Bone mineral content:** useful context, though a fitness scan isn't a diagnostic bone test. Regional data is the quiet hero here. It can show if your legs are holding muscle while your trunk drops fat. ## How InBody Works InBody is a brand of bioelectrical impedance analysis, or BIA. BIA means measuring how easily a tiny current moves through you. You stand barefoot on metal footplates and hold metal handles. A weak, painless current passes through your body. Water conducts electricity well. Muscle holds a lot of water. Fat holds very little. So the device measures resistance and estimates your composition from it. **The key word is estimates.** InBody doesn't see your tissue. It uses equations built from reference populations. If your body or hydration differs from those references, the estimate can drift. Newer models use multiple frequencies and measure each limb separately. That improves consistency. It doesn't remove the dependence on body water. ## Accuracy: What the Studies Show DEXA is widely treated as the practical reference standard for body composition. It isn't perfect. But it's consistent and far less affected by daily habits. BIA devices can track well against DEXA in controlled lab settings. Real life is messier. A [2025 study in the _European Journal of Clinical Nutrition_](https://www.nature.com/articles/s41430-025-01664-4) compared an InBody device with DEXA in everyday, non-fasted conditions. The InBody tended to underestimate fat mass versus DEXA, more so in men. What that means for you: - **A single InBody reading** can be off by a few percentage points of body fat. - **A series of InBody readings** taken the same way can still show a useful trend. - **A DEXA reading** is more trustworthy as a stand-alone number. Don't compare an InBody number directly to a DEXA number. They're different tools with different errors. Compare each tool only with itself. ## Why GLP-1 Users Should Watch Hydration This is the part most comparison articles skip. It matters more on a GLP-1 than almost anywhere else. GLP-1 medications often reduce how much you eat and drink. Some people also deal with nausea, constipation or reduced thirst. All of these can shift body water. **BIA reads body water as a stand-in for lean mass.** If you're a little dehydrated, InBody may report less muscle than you really have. Rehydrate, and the "lost" muscle can reappear. That can lead to false alarms. Or false comfort. DEXA is much less sensitive to these swings, which is one reason it's useful at key checkpoints. Drinking steadily through the day helps both your comfort and your scan accuracy. For the nutrition side of holding onto lean mass, see [our guide to protein targets on GLP-1 medication](https://www.telosrx.com/blogs/glp1/glp1-protein-targets). ## Cost, Access and Convenience Prices vary widely by city and provider. Here's the general pattern. - **DEXA:** often sold as a single scan or a package. Body composition DEXA is usually self-pay, not insurance-covered. - **InBody:** frequently included with a gym membership or offered for a small fee. - **Time:** DEXA takes about 10 minutes on the table. InBody takes about a minute. - **Scheduling:** DEXA usually needs an appointment. InBody is often walk-up. If budget is tight, one baseline DEXA plus regular InBody checks is a reasonable middle path. ## Safety: Radiation and Other Limits DEXA uses ionizing radiation, but the dose is very small. A [review in the _European Journal of Clinical Nutrition_](https://pmc.ncbi.nlm.nih.gov/articles/PMC5659281/) notes a whole-body DXA dose is below a typical day of natural background radiation. Still, a few groups should check first: - **Pregnancy:** DEXA is generally avoided during pregnancy. - **Recent contrast studies:** barium or contrast dye can interfere with readings. - **Implanted electronic devices:** BIA manufacturers typically advise against use with pacemakers or defibrillators. - **Metal implants:** hardware can distort regional DEXA results. If you're unsure, ask the scanning facility before you book. ## Which to Consider on a GLP-1 There's no single right answer. It depends on what you want to know and how often. 1. **You want the clearest muscle picture:** choose DEXA for baseline and follow-up checkpoints. 2. **You want frequent feedback:** choose InBody, taken under the same conditions each time. 3. **You're over 50 or less active:** DEXA's regional and bone data adds useful context. 4. **You're on a tight budget:** one DEXA, then InBody checks in between. 5. **You train hard and track progress closely:** the combination works best. Neither scan replaces strength. Can you climb stairs, carry groceries and lift what you lifted last month? Those functional checks matter too. **Thinking about a GLP-1 plan?** You can [compare GLP-1 options at TelosRX](https://www.telosrx.com/pages/glp-1-options). Every plan is subject to medical approval by a licensed provider after an asynchronous online review. ## How Often to Scan During GLP-1 Therapy There's no official schedule. Many clinicians and coaches follow a simple rhythm. - **Baseline:** scan before or soon after starting. - **DEXA follow-up:** every 3 to 6 months is a common interval. Changes smaller than that window can hide inside normal error. - **InBody follow-up:** every 2 to 4 weeks, if conditions are consistent. - **After dose changes:** a check after a few months on a new dose can show the trend. Scanning too often adds noise, not insight. Weekly scans mostly measure your water bottle. ## How Other Body Composition Methods Compare DEXA and InBody aren't the only options. Here's how the common alternatives stack up. - **Smart bathroom scales:** these use foot-to-foot BIA. They're cheap and easy but tend to be less precise than a full InBody device. - **Skinfold calipers:** a trained tester pinches fat at set sites. Results depend heavily on the tester's skill. - **Tape measurements:** waist and hip circumference are free and surprisingly useful. A shrinking waist usually reflects fat loss. - **Progress photos:** low-tech, but honest. Same lighting, same pose, same time of day. - **Strength logs:** if your lifts hold steady while weight drops, that's a good sign for muscle. None of these replace DEXA for precision. But a waist tape and a training log cost nothing. They pair nicely with either scan. ## How to Get Consistent Readings Consistency is what makes either scan useful. Follow the same routine every time. 1. **Same time of day.** Morning works well for most people. 2. **Same fasting state.** Skip food for a few hours beforehand, or keep it identical. 3. **Same hydration.** Drink normally the day before. Don't chug water right before. 4. **No workout first.** Exercise shifts fluid. Scan before training, not after. 5. **Same device and location.** Different machines can read differently. 6. **Light clothing, no metal.** Remove jewelry, belts and underwire if asked. Think of it like a lab test, not a gym selfie. Boring routines give the most honest numbers. ## What Your Numbers Can and Can't Tell You A scan is a snapshot. It's helpful, but it isn't a diagnosis. **What it can show:** whether fat is falling faster than lean mass, and where changes are happening. **What it can't show:** muscle quality, strength or how well your muscles work. Lean mass also includes water and organs, not only muscle. If lean mass drops faster than you'd like, the usual levers are protein, resistance training and pace of loss. See [resistance training vs cardio on GLP-1](https://www.telosrx.com/blogs/glp1/resistance-training-vs-cardio-glp1-muscle) for training specifics. Share your scan results with your provider through your TelosRX account. Any plan adjustment is subject to medical approval by a licensed provider. ## Frequently Asked Questions ### Is DEXA more accurate than InBody? Yes, in most real-world settings. DEXA directly images fat, lean tissue and bone, so it is less affected by hydration or meals. InBody estimates composition from electrical resistance, so readings can shift with body water. InBody still works well for tracking trends when you test under the same conditions each time. ### Can InBody detect muscle loss on a GLP-1? It can show a trend, but read it carefully. GLP-1 medications can lower food and fluid intake, and dehydration can make InBody report less lean mass than you have. Test at the same time, fasting state and hydration level. Confirm meaningful drops with a DEXA scan when possible. ### How often should I get a DEXA scan while losing weight? Many people scan at baseline and then every 3 to 6 months. Shorter gaps often fall within normal measurement error, so changes are hard to interpret. If your dose or training changes, a follow-up after a few months can show the trend. Your provider can help decide timing that fits your plan. ### Why do my DEXA and InBody results disagree? They use different methods and different equations. DEXA measures X-ray absorption, while InBody estimates tissue from electrical resistance and body water. Studies show InBody often reads body fat lower than DEXA. Compare each device only with its own earlier readings, not with the other machine. ### Is a DEXA scan safe? For most adults, yes. A whole-body DEXA scan uses a very low radiation dose, below a typical day of natural background exposure. It is generally avoided during pregnancy. Tell the facility about recent contrast studies or metal implants, since both can affect your results. ### Does a body composition scan replace strength testing? No. A scan shows how much lean mass you have, not how well your muscles perform. Lean mass also includes water and organs. Simple checks like stair climbing, grip strength or tracking your lifts add useful context. Together, scans and strength checks give a fuller picture. _TelosRX is LegitScript-certified. Compounded medications are not FDA-approved and are prepared under federal compounding regulations. Approval is subject to evaluation by a licensed provider; approval is not guaranteed. Individual results vary. TelosRX operates as an online-first, asynchronous telehealth service._ Start your private evaluation at [TelosRX](https://telosrx.com). **Tags:** bioimpedance, body composition, comparison, DEXA vs InBody, GLP-1 muscle loss, lean mass --- > Source: [Telos RX](https://www.telosrx.com/blogs/glp1/dexa-vs-inbody-glp1-muscle-tracking)