GLP-1 Body Changes and Muscle Loss Prevention

By Amanda Boike Fitness

When weight begins coming off, changes in your body can raise questions you weren't expecting. Your clothes may fit differently, the shape of your backside may change, or the skin around your arms may look looser. Alongside the relief or satisfaction of losing weight, there can be uncertainty about whether you are also losing something you want to keep.

Substantial weight loss can involve both fat and lean tissue, including muscle. Strength training and adequate nutrition help support muscle during that process, and a useful exercise routine can begin while weight is still changing. The goal is to give the muscles regular, challenging work that fits your current strength, appetite, and recovery. 2 6

Understanding the visible changes takes another step. Body shape reflects the muscle underneath, the fat covering it, and the skin around both. As fat volume decreases, skin may look looser or contours may change even when muscle function remains good. This distinction helps explain why strength training can be valuable while leaving some appearance changes unresolved. 8 9

Does Ozempic cause muscle loss?

Research shows that people can lose lean mass during weight loss with semaglutide and related medications. How much of that change represents skeletal muscle, and what it means for strength, requires more interpretation. These studies measure changes during treatment; they do not isolate a direct muscle-damaging effect of the medication from the effects of losing substantial weight. 1 2

In the exploratory STEP 1 body-composition substudy, 140 adults with overweight or obesity underwent DXA scans. After 68 weeks, the semaglutide group had lost 19.3% of its initial fat mass and 9.7% of its initial lean body mass. Fat declined more, so lean tissue accounted for a larger proportion of the remaining body weight. This was semaglutide 2.4 mg studied for obesity treatment, rather than a trial of every Ozempic dose. 1

The percentages describe changes from each tissue's starting amount. The 9.7% figure therefore means a reduction from baseline lean mass, not that 9.7% of the weight lost was muscle. A person can have a more favorable ratio of lean tissue to fat while having less lean tissue overall.

A 2025 SURMOUNT-1 analysis examined 160 participants with body-composition data, including 124 receiving tirzepatide and 36 receiving placebo. Tirzepatide acts on both GIP and GLP-1 receptors. In the medication group, average weight fell 21.3% over 72 weeks; approximately 74% of the weight lost was fat and 26% was lean mass. The placebo group lost considerably less weight, with similar proportions of fat and lean loss. STEP 1 was sponsored by Novo Nordisk, and SURMOUNT-1 by Eli Lilly. 1 2

Lean mass includes more than skeletal muscle. DXA measures nonfat soft tissue, including organs and their water content. It provides a useful picture of body composition, but the scan alone cannot establish how much contractile muscle was lost or whether everyday function declined. Training performance and clinical assessment help put that measurement in context. 2

What GLP-1 sarcopenia concerns actually mean

Sarcopenia is a clinical muscle disorder assessed through strength, muscle quantity or quality, and physical performance. Under the European Working Group's revised consensus, low strength raises suspicion, low muscle quantity or quality confirms the diagnosis, and poor physical performance indicates greater severity. A change in appearance alone is insufficient to establish it. 3

Someone starting treatment with limited muscle reserves deserves particular attention, especially with older age, inactivity, illness, or inadequate nutrition. Progressively harder chair rises, increasing difficulty carrying familiar objects, or persistent weakness are reasons to seek assessment. These observations give a clinician more useful information than a concern about sagging skin alone.

Why eating less can make muscle harder to maintain

Muscle is continually being renewed as proteins are made and broken down. Maintaining it depends on enough new protein being made over time to balance those losses. Eating substantially less can make that balance harder to sustain, while a smaller appetite can reduce protein intake almost unnoticed.

In a small 2010 study of physically active adults, ten days of moderate energy restriction reduced fasting muscle protein synthesis by about 19%. Although this short laboratory study was not conducted in GLP-1 users, it illustrates one way an energy deficit can affect muscle maintenance. Resistance exercise supplies an important stimulus in the other direction: a 2024 systematic review found that a session could increase muscle protein synthesis for up to 48 hours, with variation across participants and training conditions. 4 5

Over weeks and months, the results also depend on nutrition and recovery. Murphy and Koehler's meta-analysis found smaller lean-mass gains from resistance training during an energy deficit than without one, while strength gains were comparable. During active weight loss, preserving existing muscle may be a worthwhile result. As intake and weight stabilize, there may be more opportunity to build additional muscle. 7

If meals have become difficult to finish and exercise performance keeps declining, increasing the workout load alone is unlikely to address the whole problem. Reviewing intake and medication symptoms with the care team can help make training more manageable. The 2025 joint advisory from four nutrition and obesity organizations treats adequate nutrition and strength training as connected priorities during GLP-1 treatment. 6

Understanding GLP-1 body changes in different areas

Glutes and the appearance called Ozempic butt

The buttocks get their shape from glute muscles, overlying fat, and skin. Losing fat changes the outline; skin may also become looser after substantial weight loss. The informal label “Ozempic butt” can describe these changes without telling us how much glute muscle was lost. 8

For training, the useful question is what work the glutes receive each week. A familiar daily walk offers activity, but progressively challenging bridges, hip hinges, and squats provide a more deliberate resistance stimulus. As these exercises become easier, the resistance or repetitions can increase. Developing the underlying muscle can contribute to shape and strength, with the outcome also influenced by the remaining fat and skin.

Arms, breasts, and the upper chest

Smaller arms can reflect changes in fat, muscle, or both. Breast changes more directly involve fat volume and the skin surrounding the tissue. The pectoral muscles lie underneath the breasts, so chest exercise trains a different structure from the tissue responsible for breast volume. 9

A floor press or wall push-up trains the chest and triceps for pushing tasks. Rows train the upper back and arms for pulling. Keeping both in the program gives the upper body regular work even when one visible area attracts most of the attention. Our guide to what builds muscle definition explains the relationship between muscle and body fat in more detail.

Feet and plantar cushioning

“Ozempic feet” is an informal name for concerns that still need an explanation. The heel has a specialized fat pad that cushions and distributes pressure during walking. A 2022 scoping review found limited evidence for diagnosing and treating heel fat pad syndrome, and did not establish GLP-1 medication as a cause. Foot muscles and this cushioning are separate tissues. 10

New pain affecting walking, especially with numbness or swelling, deserves assessment. In the meantime, comfortable seated or floor-based exercises may allow some strength work while reducing time spent loading a painful foot. The appropriate choices depend on the cause and the positions tolerated.

Facial volume and posture

Facial hollowing after substantial weight loss often involves reduced fat volume and changes in soft-tissue support. Strength training elsewhere in the body does not replace that facial volume. 8

Posture is better understood through how someone moves and feels. A changed silhouette may simply accompany weight loss, while increasing difficulty standing comfortably or carrying everyday loads deserves closer attention. Rows and other strength exercises can build capacity for physical tasks. Persistent pain or a pronounced postural change calls for individual assessment of what is contributing.

How cardio fits into muscle preservation

Walking, cycling, and other aerobic activities can remain part of a strength plan. The important programming question is how the activities fit together, particularly when appetite or energy is lower. Resistance exercise provides a muscle-building stimulus that an aerobic routine may not supply to the same extent.

In a six-month randomized trial of 160 older adults with obesity, all exercise groups followed a weight-loss diet. Lean mass declined by about 5% with aerobic training, 2% with resistance training, and 3% with combined training. The combined group improved physical function most. These participants were at least 65 and had mild to moderate frailty; the trial did not study modern GLP-1 treatment or establish that high-intensity cardio causes muscle wasting. 11

The results support including resistance training during weight loss, with realistic expectations about preservation. For someone who enjoys cardio and recovers well, it can complement strength work. Frequent hard sessions become a concern when they leave too little energy for resistance training, eating, or recovery. Adjusting that workload is more useful than treating all cardio as a threat to muscle.

Three priorities for GLP-1 muscle loss prevention

1. Give muscles progressive resistance

Low-impact strength exercises allow substantial muscular effort in a stable position. A dumbbell floor press, for example, can become challenging for the chest and arms while the rest of the body stays supported. The useful challenge comes from moving the resistance, without requiring jumping or rushed transitions.

Choose a resistance that makes later repetitions meaningfully harder while allowing controlled movement. For a familiar exercise, finishing with roughly two or three good repetitions still possible is a reasonable coaching starting point; beginners can leave more room while learning. Research suggests muscle growth generally benefits from working closer to muscular failure, although the precise relationship remains uncertain. 13

Repeat exercises consistently enough to see when they become easier. If the same weight now allows more controlled repetitions, that is information you can use to increase the challenge. Our guide to starting strength training covers these early decisions.

2. Make protein achievable across the day

The joint advisory discusses 1.2–1.6 grams of protein per kilogram daily during active weight reduction, with uncertainty about which body-weight measure to use in people with obesity. A clinician or dietitian can help choose an appropriate target, particularly with kidney disease or difficulty eating. 6

Once the target is chosen, smaller portions across the day may be easier to manage. For an illustrative 90-gram target, three meals with roughly 25 grams plus a 15-gram snack would add up. Two large eggs supply about 12 grams; paired with half a cup of cottage cheese whose label lists 13 grams, they would provide approximately 25 grams. Check serving sizes and labels when building other meals with yogurt, tofu, fish, or a tolerated supplement. 17

Protein distribution is a practical tool for reaching the day's intake. Evidence for a special advantage from evenly distributing protein remains mixed, particularly for strength and protein turnover. If a larger meal is uncomfortable, dividing it into smaller eating occasions may help. A workable pattern should also leave room for the other foods needed for adequate nutrition. 6 14

3. Choose positions that let the intended muscles work

Exercise selection matters when discomfort or balance limits the movement. If holding a bent-over row tires the lower back before the upper back, supporting the free hand can make the exercise easier to organize. A higher chair can reduce squat depth; a floor press offers an alternative when a push-up position is uncomfortable. Our guide to low-impact strength exercises explores these options.

Low impact alone does not guarantee that an exercise suits a particular joint. Adjust the position, range, or resistance when discomfort disrupts movement, and seek individual guidance when symptoms persist.

Medication symptoms also affect exercise readiness. Ozempic's prescribing information warns about dehydration associated with gastrointestinal reactions and hypoglycemia when combined with insulin or certain other diabetes medicines. Persistent vomiting, inability to maintain fluids, or suspected low blood sugar requires an appropriate medical response. 15

A manageable starting week at home

For a beginner who comfortably performs the movements below, two nonconsecutive full-body sessions, such as Monday and Thursday, can establish a routine. ACSM's 2026 guidance emphasizes training major muscle groups at least twice weekly. The GLP-1 joint advisory recommends aiming for strength training at least three times weekly. Starting with two sessions is a coaching option for building participation; the eventual workload should reflect training history, recovery, and individual needs. 6 12

Allow roughly 25–35 minutes, including a few minutes of comfortable movement and light practice repetitions. Begin with one or two sets of each exercise. Complete the sets for one exercise before moving to the next, resting one to two minutes between sets and exercises, or longer until ready. The repetition ranges below are starting guides. 16

Exercise	Starting repetitions per set	Setup or adjustment
Supported chair squat	8–12	Use a higher seat or hand support
Dumbbell hip hinge	8–12	Practice a shorter range while learning
One-arm supported dumbbell row	8–12 per side	Support the free hand on a stable surface
Wall push-up or dumbbell floor press	8–12	Choose the comfortable position
Supine heel slide	6–10 per side	Slowly slide one heel away and back with comfortable trunk control

For the row, train both sides before the longer rest, taking a brief pause between sides if needed. For heel slides, lie on your back with knees bent and feet down; alternate sides and shorten the slide if the trunk becomes difficult to control. These are general beginner exercises, not a validated GLP-1 treatment protocol.

When the upper end of a repetition range becomes comfortably repeatable with good control, try a small resistance increase. If recovery and performance remain steady, adding a third nonconsecutive session is one option for increasing weekly training. An experienced lifter will usually need to adapt her existing workload rather than replace it with this introductory routine.

How to judge whether the plan is helping

A brief record of weights, repetitions, and symptoms makes progress easier to recognize. It can show whether a familiar exercise is becoming easier or whether a repeated decline needs attention. Everyday tasks offer another perspective, such as how comfortably you rise from a chair or carry groceries.

Strength and muscle mass can change differently: energy-deficit research found that strength could improve even when lean-mass gains were limited. Stable performance is encouraging, while muscle preservation itself requires more than a training log to assess. If familiar activities become progressively harder, a clinician can evaluate strength and physical performance alongside body-composition information. 3 7

Bringing the plan into ABF Online

Following these principles means deciding what to train each week, choosing resistance, and recognizing when an exercise needs adjusting. I created ABF Online to make those decisions easier for women who want a guided strength routine at home.

The program offers 30-minute classes and two-, three-, or four-day plans. Demonstrations and positioning cues help explain how to perform each movement and where to feel the work, so the principles in this article become decisions you can practice. Medication and individualized nutrition care remain with the appropriate professionals.

Explore ABF Online and try the sample upper-body class to see how the coaching feels in a workout.

Sources

1. King R, Wilding JPH, Batterham RL, and colleagues. Impact of Semaglutide on Body Composition in Adults with Overweight or Obesity: Exploratory Analysis of the STEP 1 Study. 2021. Association of British Clinical Diabetologists conference poster, identifying an earlier presentation at ENDO. Trial sponsored by Novo Nordisk. Original poster.

2. Look M, Dunn JP, Kushner RF, and colleagues. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight. 2025. Diabetes, Obesity and Metabolism 27:2720–2729. DOI: 10.1111/dom.16275. Trial funded by Eli Lilly. Full article. The published correction changes the units on two Figure 4 axes from percentages to kilograms; it does not change the statistics cited here.

3. Cruz-Jentoft AJ and colleagues. Sarcopenia: revised European consensus on definition and diagnosis. 2019. Age and Ageing 48:16–31. DOI: 10.1093/ageing/afy169. Consensus statement.

4. Pasiakos SM and colleagues. Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults. 2010. Journal of Nutrition 140:745–751. Study record.

5. Davies RW, Lynch AE, Kumar U, and Jakeman PM. Characterisation of the Muscle Protein Synthetic Response to Resistance Exercise in Healthy Adults: A Systematic Review and Exploratory Meta-Analysis. 2024. Translational Sports Medicine, article 3184356. DOI: 10.1155/2024/3184356. Review.

6. Mozaffarian D and colleagues, for the American College of Lifestyle Medicine, American Society for Nutrition, Obesity Medicine Association, and The Obesity Society. Nutritional priorities to support GLP-1 therapy for obesity: A joint advisory. 2025. Obesity Pillars 15:100181. DOI: 10.1016/j.obpill.2025.100181. Joint advisory.

7. Murphy C and Koehler K. Energy deficiency impairs resistance training gains in lean mass but not strength: A meta-analysis and meta-regression. 2022. Scandinavian Journal of Medicine and Science in Sports 32:125–137. DOI: 10.1111/sms.14075. Authors’ university research record.

8. American Society of Plastic Surgeons. The GLP-1 effect: From body to face and what happens next. 2026. Professional-society reporting on aesthetic changes; not an exercise trial. Article.

9. American Society of Plastic Surgeons. GLP-1 and breast surgery: How weight loss medications are reshaping aesthetic options. 2026. Professional-society reporting with plastic-surgeon interviews. Article.

10. Chang AH, Rasmussen SZ, Jensen AE, Sørensen T, and Rathleff MS. What do we actually know about a common cause of plantar heel pain? A scoping review of heel fat pad syndrome. 2022. Journal of Foot and Ankle Research 15:60. DOI: 10.1186/s13047-022-00568-x. Review.

11. Villareal DT and colleagues. Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults. 2017. New England Journal of Medicine 376:1943–1955. DOI: 10.1056/NEJMoa1616338. Randomized trial.

12. Currier BS, D’Souza AC, Fiatarone Singh MA, and colleagues. American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. 2026. Medicine and Science in Sports and Exercise 58:851–872. DOI: 10.1249/MSS.0000000000003897. Study record and ACSM’s official guidance summary.

13. Robinson ZP and colleagues. Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions. 2024. Sports Medicine 54:2209–2231. DOI: 10.1007/s40279-024-02069-2. Review record.

14. Jespersen SE and Agergaard J. Evenness of dietary protein distribution is associated with higher muscle mass but not muscle strength or protein turnover in healthy adults: a systematic review. 2021. European Journal of Nutrition 60:3185–3202. DOI: 10.1007/s00394-021-02487-2. Review record.

15. Novo Nordisk. Ozempic prescribing information. 2026 FDA-approved labeling. Relevant sections: hypoglycemia with insulin or insulin secretagogues; acute kidney injury due to volume depletion; gastrointestinal adverse reactions. Prescribing information.

16. American College of Sports Medicine. Progression models in resistance training for healthy adults. 2009. Medicine and Science in Sports and Exercise 41:687–708. DOI: 10.1249/MSS.0b013e3181915670. Used for familiar novice repetition, rest, and progression principles; the article uses the 2026 update for current overall guidance. Position stand.

17. American Egg Board. Protein, Fat, and Phospholipids — More Reasons to Love Eggs. Nutrition-label information used for the approximate protein content of large eggs. The cottage-cheese example is conditional on a product label listing 13 grams per half cup. Nutrition information.