--- title: 'Should you get a body-composition scan before you start?' description: 'A scan taken before or in the first weeks is the only thing that makes every later scan mean something. What to ask for, what it costs, and what to do if you already started.' canonical: https://proforta.com/learn/body-composition-scan-before-you-start/ generated: 2026-10-08 --- Should you get a body-composition scan before you start? Guide · week zero # Should you get a body-composition scan before you start? A scan is a snapshot; ProForta helps you maintain muscle while you lose the weight, measured over twelve weeks, and the [60-second self-check](https://proforta.com/check?utm_source=proforta&utm_campaign=learn-body-composition-scan-before-you-start) gives you a number today. About three minutes to read If you can get one, get it before the weight starts moving. A single scan is a snapshot and tells you very little on its own. The reading that answers the question you care about, how much of what you lost was fat, only exists as the difference between two scans. Without a week-zero number, every later scan is a photograph with nothing to compare it to. People search for this under semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). The body-composition answer below is the same whichever one you are on, and it is the same again if you are losing weight without any of them. ## Why the first scan is worth more than the second The trials that put numbers on lean-mass loss did it by scanning people at the start and again at the end. That is not a technicality of trial design, it is the only way the measurement works. The SURMOUNT-1 substudy could report roughly 75 percent fat and 25 percent lean of the weight lost precisely because it knew both endpoints. Your own version of that is two scans, twelve weeks apart, on the same machine at the same place. Book the second when you book the first, because the thing most likely to break the pair is a scheduling gap three months from now. ## What to ask for - **A whole-body composition scan**, not a bone-density scan of the hip and spine. Those are different protocols answering different questions. - **The same machine for the second scan**, and a note of which one it was. Centres run different manufacturers' machines and they do not read the same as each other. - **The report as a file you keep.** Most centres email it the same day. It is yours. - **The total, fat, lean and bone figures on the summary page.** That is the part that matters; the rest of the report is detail. The practical details, what a scan costs in the United States, where to find one, and how the report gets into ProForta, are on the [getting a scan guide](https://proforta.com/dexa). ProForta has no arrangement with any centre and receives nothing from any of them. ## If you already started Then the best available week zero is this week, and that is a genuinely good outcome rather than a consolation. You lose the ability to measure what has already happened. You keep the ability to measure everything from here, which is most of the window that is still in front of you. The 2025 joint advisory's levers, enough protein (1.5 grams per kilogram of fat-free mass a day, or 80 to 120 grams a day without a scan) and strength training at least three times a week, work from whenever you start them. ## If a scan is not available to you Plenty of people cannot get one, and the answer is not to go without any baseline. Write down three benchmark lifts, a chair-stand count and a waist measurement this week, and repeat them monthly. That set will not tell you kilograms of lean mass, and it will tell you the direction, which is most of what a decision needs. ## What you can check this week - **Find one centre and ask about a whole-body composition scan, self-pay.** One phone call settles availability, price and whether a referral is needed where you live. - **Book both appointments in the same call.** Twelve weeks apart, same machine. - **Set the free baseline anyway.** Three lifts, a chair-stand count and a waist measurement, today, whether or not the scan happens. - **Run the [60-second self-check](https://proforta.com/check?utm_source=proforta&utm_campaign=learn-body-composition-scan-before-you-start)** to see what trial averages suggest for a loss the size of yours, and a daily protein target in grams. ## Where ProForta comes in ProForta holds your scan numbers on a private node that belongs to you and reads them against the rest of your data. It shows you words about them, whether your pair is complete and whether muscle held, never raw values. The report itself stays with you. LifeCare.ID® carries the identity and the consent record. ProForta is a wellness tool, not medical advice. Nothing here speaks to your medicine or your care. Your prescriber stays the decision-maker on both. ## Watch it instead of guessing The ProForta Challenge is twelve weeks with your muscle actually watched while you work on the weight, however you are going about it. It is free, it is a small beta on one private node, and the only person you are ever compared with is you at the start of it. [Join the ProForta Challenge](https://app.proforta.com/join?utm_source=proforta&utm_campaign=learn-body-composition-scan-before-you-start) [Take the 60-second self-check](https://proforta.com/check?utm_source=proforta&utm_campaign=learn-body-composition-scan-before-you-start) The self-check runs entirely in your browser and sends nothing anywhere. If you would rather look around first, [open the demo](https://proforta.com/demo), nothing to install and no account to create. ## Related questions - [Are smart scales accurate enough to track muscle?](https://proforta.com/learn/tracking-body-composition-at-home) - [How much of GLP-1 weight loss is muscle?](https://proforta.com/learn/how-much-glp1-weight-loss-is-muscle) - [What are the signs you are losing muscle, not fat?](https://proforta.com/learn/signs-you-are-losing-muscle) - [What happens to your muscle when you come off a GLP-1?](https://proforta.com/learn/keeping-muscle-when-you-stop) - [Getting a DEXA scan, a United States guide](https://proforta.com/dexa) [All ten questions](https://proforta.com/learn) ## Sources - SURMOUNT-1 body-composition substudy (tirzepatide; roughly 75 percent fat and 25 percent lean of the weight lost). Look et al., Diabetes, Obesity and Metabolism 2025, doi:10.1111/dom.16275. [PMC11965027](https://pmc.ncbi.nlm.nih.gov/articles/PMC11965027/) - 2025 joint advisory on nutritional priorities to support GLP-1 therapy, American College of Lifestyle Medicine, American Society for Nutrition, Obesity Medicine Association and The Obesity Society. Obesity Pillars 2025;15:100181. [PMC12264624](https://pmc.ncbi.nlm.nih.gov/articles/PMC12264624/) Corrected 8 October 2026: an earlier version of this page attributed a protein minimum of 1.2 grams per kilogram a day to the 2025 joint advisory. The advisory does not give that figure; the figures above are its own. [ProFortaPowered by LifeCare.ID®](https://proforta.com/) © 2026 Enbarca Inc., doing business as HCVC.net. All rights reserved.