Generic semaglutide, the drug in Ozempic and Wegovy, is new in Canada this year. On April 28, 2026, Canada became the first G7 country to approve a generic version, and on June 29 Health Canada approved Sevmia, the first generic for weight management. Health Canada notes that many generic drugs in Canada cost 45 to 90% less than the brand name versions (Health Canada, 2026).
More people may now be starting these drugs, and one question comes up a lot: will I lose muscle too? The short answer is that some of the weight you lose will be lean mass, and strength training is the best tool we have to keep more of it.
Please read first. This post is general information, not medical advice. Ozempic, Wegovy and similar drugs are prescription medicines. Talk with your doctor or pharmacist before you start, stop or change one, and before you make a big change to how you eat or train. If you feel unwell, get medical care.
How much of the weight lost is muscle?
When anyone loses a lot of weight, some lean mass goes with the fat. Lean mass is everything that isn't fat: muscle, but also water, organs and other tissue.
- In the STEP 1 trial of semaglutide, of the average 13.6 kg weight loss, about 8.3 kg (62%) was fat and 5.3 kg (38%) was lean mass. Muscle is about half of lean mass, so roughly 20% of the weight lost was muscle (Mozaffarian et al., 2025).
- It may differ between men and women. Modeling data suggest that, without structured strength training, muscle makes up about 10 to 15% of the weight lost in women and 20 to 25% in men (Mozaffarian et al., 2025).
- It isn't only the drugs. A 2026 meta analysis pooled 20 randomized trials with 15,782 people. On average, lean mass made up 35.2% of the weight lost with semaglutide, 26.8% with liraglutide and 25.4% with tirzepatide. Diet and lifestyle programs without a drug were similar, at 26.2%. Lifestyle programs that included resistance training had the lowest share, at 17.5% (Eisa & Barood, 2026).
That last comparison comes from different trials pooled together, not from people tested head to head, and results varied a fair amount between trials. Still, the pattern matches what experts describe: big weight loss of any kind costs some lean mass, and these drugs tend to produce bigger losses (Mozaffarian et al., 2025).
There is good news too. Because fat drops more than lean mass, lean mass as a share of body weight actually went up, by about 1.8%, in a 2026 meta analysis of 7 placebo controlled trials with 821 people, even though people lost about 1.7 kg more lean mass than with a placebo (about 5.4 kg more with semaglutide). The authors concluded that lean mass loss shouldn't be a reason to avoid the drugs, but that treatment should come with nutrition and exercise support (Laverde et al., 2026).
How much of the weight lost was lean mass?
Numbers from published trials and reviews. Switch views to compare.
Most of these trials measured body composition, not strength. One expert advisory suggests also checking strength and function with simple tests like sit to stand from a chair, climbing stairs or getting up and walking (Mozaffarian et al., 2025).
Strength training is what keeps muscle
A joint advisory from four lifestyle medicine, nutrition and obesity groups put it plainly: strength training, or mixed strength and aerobic training, is well established to help preserve lean mass during weight loss. Aerobic exercise alone has a smaller effect (Mozaffarian et al., 2025).
- Exercise saved about half the lean mass. A 2026 meta analysis of 34 randomized trials with 1,455 people with overweight or obesity compared calorie restriction alone with calorie restriction plus exercise. Adding exercise kept about 0.87 kg more fat free mass and prevented nearly half (45.7%) of the loss (Deller et al., 2026).
- Lifting may beat cardio alone. In the same review, mixed training kept about 1.20 kg and strength training about 0.83 kg, while endurance training alone (0.51 kg) fell just short of statistical significance. A direct test between training types found no significant difference, so treat the ranking as a hint, not a final answer. Trial quality was rated fair, and these were diet trials, not drug trials (Deller et al., 2026).
- The drug plus exercise beat either one alone. In a one year Danish trial, 195 people with obesity first lost an average of 13.1 kg on a low calorie diet, then got exercise, liraglutide (an older daily drug in the same family), both, or a placebo. The combination cut body fat percentage by 3.9 points, about twice as much as exercise (1.7) or liraglutide (1.9) alone. Only the combination improved blood sugar control, insulin sensitivity and fitness (Lundgren et al., 2021).
How much training?
- Canada's baseline. The Canadian 24 Hour Movement Guidelines call for at least 150 minutes a week of moderate to vigorous aerobic activity and muscle strengthening activities at least twice a week (Ross et al., 2020).
- While on these drugs. The joint advisory recommends strength training at least 3 times a week plus at least 150 minutes of moderate aerobic exercise, matched to your fitness level (Mozaffarian et al., 2025). A 2026 expert consensus led from the University of Toronto recommends a program tailored to each person, built on at least 150 minutes a week of moderate to vigorous aerobic activity plus resistance training, in line with guidelines that suggest resistance training 2 to 3 times a week (Sievenpiper et al., 2026). That consensus was built mostly on indirect evidence, so think of it as expert guidance rather than a tested prescription.
Plan your training week
Tap a day to switch between rest, strength, cardio or conditioning, and mobility, yoga or breathwork. Then set how long your cardio sessions are.
Targets: at least 150 minutes of moderate to vigorous aerobic activity and muscle strengthening at least twice a week (Canadian 24 Hour Movement Guidelines, Ross R, et al. Appl Physiol Nutr Metab 2020;45(10 Suppl. 2):S57-S102, PubMed). Strength training at least 3 times a week plus at least 150 minutes of moderate aerobic exercise while on these drugs (Mozaffarian D, et al. Am J Clin Nutr 2025;122(1):344-367, PubMed). Mobility, yoga and breathwork are shown separately because these targets count aerobic and muscle strengthening activity. General information, not medical advice.
Protein matters, but it can't do the job alone
Both expert groups make the same point: more protein alone won't keep your muscle. The advisory calls higher protein "likely inadequate" without structured strength training, and the consensus states that a high protein intake alone does not increase muscle mass (Mozaffarian et al., 2025; Sievenpiper et al., 2026). Protein supports the training. It doesn't replace it.
- The basic daily allowance is 0.8 g per kg of body weight. Higher targets of 1.2 to 1.6 g per kg have been proposed during active weight loss (Mozaffarian et al., 2025). The consensus suggests 1.2 to 1.5 g per kg of actual body weight during the weight loss phase, and at least 0.8 g per kg once you are maintaining (Sievenpiper et al., 2026).
- Larger bodies may not need the full number. Using actual body weight can overestimate protein needs in people with obesity. A simple target of 80 to 120 g a day is one alternative (Mozaffarian et al., 2025).
- Stay inside the guardrails. The advisory says intake shouldn't fall below 0.4 to 0.5 g per kg a day, and that intake at or above 2 g per kg should be avoided over long periods (Mozaffarian et al., 2025).
- Low appetite? Small, frequent meals can help when hunger is low. Smoothies or protein drinks made with milk or yogurt, cottage cheese and soups often go down easier than heavy foods like red meat (Mozaffarian et al., 2025).
If you have kidney disease or another medical condition, ask your doctor or a registered dietitian which protein target fits you.
Protein target calculator
Slide to your body weight to see the daily protein ranges experts suggest during weight loss.
Ranges from Mozaffarian D, et al. Am J Clin Nutr 2025;122(1):344-367 (PubMed) and Sievenpiper JL, et al. Obes Pillars 2026;17:100228 (PubMed). Protein supports strength training. It doesn't replace it. General information, not medical advice. If you have kidney disease or another medical condition, ask your doctor or a registered dietitian which target fits you.
Why keeping muscle matters if you stop
Many people stop these drugs. The advisory cites stopping rates of 50 to 67% at 1 year (Mozaffarian et al., 2025). In the STEP 1 extension, people lost 17.3% of their weight over 68 weeks on semaglutide. One year after the drug and the lifestyle program ended, they had regained 11.6 percentage points, about two thirds of what they lost (Wilding et al., 2022). That analysis was exploratory, but it shows why habits you can keep, like regular strength training and enough protein, are worth building while you are on the drug.
The drug is one part
The medication lowers appetite. What you do with your training and food decides how much muscle you keep.
- Lift at least 2 times a week, and 3 if you can, with weights that challenge you and a plan that progresses. See balancing strength training with cardio.
- Hit your protein target. See how much protein you need for muscle growth.
- Expect plateaus. Weight loss slows for everyone. See overcoming weight loss plateaus.
- Train for your blood sugar too. See exercise and insulin resistance.
How we can help
At Inner G, a fitness studio in Concord, our coaches run small group strength, conditioning, mobility, yoga and breathwork classes, capped at 16 people, so a coach can teach you the lifts, watch your form and progress your training. If keeping muscle while you lose weight is your main goal, one on one personal training gives you a plan designed around your strength, recovery and schedule, and nutrition coaching can help you reach your protein target when your appetite is low.
We're coaches, not doctors, so we don't give advice about medication. That stays with your doctor or pharmacist.
- Try our $30 seven day trial (+ HST) with unlimited classes. Join by day 5 and your $30 is credited toward your membership. Book your class.
- Want a plan of your own? See personal training in Vaughan.
- Want help with food? See nutrition coaching in Vaughan.
- Prefer a slower pace? See one on one training focused on balance and strength.
Questions? Call (289) 536-8066 or email g-squad@innerg.ca.
References
Deller M, Weiershaus J, Held S, Brinkmann C. (2026). Effects of calorie restriction with and without strength, endurance or mixed training on fat-free and skeletal muscle mass in overweight or obese individuals: a systematic review with pairwise meta-analysis and network meta-analysis of randomized controlled studies. Diabetes, Obesity and Metabolism, 28(8):6810-6823. doi:10.1111/dom.70873. PubMed · PMC
Eisa N, Barood O. (2026). Lean mass changes with incretin therapy versus lifestyle intervention: a systematic review and meta-analysis of randomised controlled trials. Diabetes, Obesity and Metabolism, 28(6):4818-4827. doi:10.1111/dom.70666. PubMed
Health Canada. (2026, June 29). Canada approves first generic semaglutide for weight loss. News release. Read the news release
Laverde LP, Muñoz-Velandia OM, Alfonso D, Gómez Medina AM. (2026). Effect of GLP-1 receptor agonists at doses for obesity management on muscle health: systematic review and meta-analysis of randomized controlled trials (RCTs). International Journal of Obesity, 50(8):1638-1646. doi:10.1038/s41366-026-02118-y. PubMed · PMC
Lundgren JR, Janus C, Jensen SBK, Juhl CR, Olsen LM, Christensen RM, Svane MS, Bandholm T, Bojsen-Møller KN, Blond MB, Jensen JB, Stallknecht BM, Holst JJ, Madsbad S, Torekov SS. (2021). Healthy weight loss maintenance with exercise, liraglutide, or both combined. New England Journal of Medicine, 384(18):1719-1730. doi:10.1056/NEJMoa2028198. PubMed
Mozaffarian D, Agarwal M, Aggarwal M, Alexander L, Apovian CM, Bindlish S, Bonnet J, Butsch WS, Christensen S, Gianos E, Gulati M, Gupta A, Horn D, Kane RM, Saluja J, Sannidhi D, Stanford FC, Callahan EA. (2025). Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. American Journal of Clinical Nutrition, 122(1):344-367. doi:10.1016/j.ajcnut.2025.04.023. PubMed · PMC. A 2026 correction (doi:10.1016/j.ajcnut.2026.101303) fixed one sentence about a separate study and did not change the numbers used here.
Ross R, Chaput JP, Giangregorio LM, Janssen I, Saunders TJ, Kho ME, Poitras VJ, Tomasone JR, El-Kotob R, McLaughlin EC, Duggan M, Carrier J, Carson V, Chastin SF, Latimer-Cheung AE, Chulak-Bozzer T, Faulkner G, Flood SM, Gazendam MK, Healy GN, Katzmarzyk PT, Kennedy W, Lane KN, Lorbergs A, Maclaren K, Marr S, Powell KE, Rhodes RE, Ross-White A, Welsh F, Willumsen J, Tremblay MS. (2020). Canadian 24-Hour Movement Guidelines: an integration of physical activity, sedentary behaviour, and sleep (official title shortened). Applied Physiology, Nutrition, and Metabolism, 45(10 Suppl. 2):S57-S102. doi:10.1139/apnm-2020-0467. PubMed · Guideline summary: CSEP
Sievenpiper JL, Ard J, Blüher M, Chen W, Dixon JB, Fitch A, Gigliotti L, Khunti K, Lecube A, Lean MEJ, Mittendorfer B, Pfeiffer AFH, Ryan DH, Vilsbøll T, Van Gaal LF. (2026). Nutritional and lifestyle supportive care recommendations for management of obesity with GLP-1 based therapies: an expert consensus statement using a modified Delphi approach. Obesity Pillars, 17:100228. doi:10.1016/j.obpill.2025.100228. PubMed · PMC
Wilding JPH, Batterham RL, Davies M, Van Gaal LF, Kandler K, Konakli K, Lingvay I, McGowan BM, Oral TK, Rosenstock J, Wadden TA, Wharton S, Yokote K, Kushner RF; STEP 1 Study Group. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism, 24(8):1553-1564. doi:10.1111/dom.14725. PubMed · PMC