Semaglutide and Exercise: What the Research Says About Muscle, Energy, and Results

GLP-1 medications like semaglutide have transformed how people approach weight loss. If you're taking one of these drugs or considering starting, you probably have questions about what happens to your body, how exercise fits into the picture, and whether you can protect your hard-earned muscle along the way. The research is clear on a few things, and knowing what to expect can help you make the most of your results.

Does Semaglutide Give You Energy?

Unfortunately, semaglutide doesn't give you energy. It works primarily by reducing appetite and food intake, which leads to weight loss over time. Reports from people taking semaglutide in multiple clinical trials show no increase in energy or reduced fatigue from the medication itself.

So, if you're hoping semaglutide will make your workouts feel easier or give you more pep throughout the day, you'll want to manage those expectations. But, you could still experience feeling more energetic, it's just that those benefits come indirectly from losing weight and improving overall health, not from the drug itself.

Does Semaglutide Cause Muscle Loss?

When you lose weight, regardless of whether you're taking GLP-1 medications or not, you'll lose both fat and lean mass, but how much muscle you lose depends on a few factors.

On semaglutide, multiple meta-analyses show that about 20 to 40 percent of the total weight lost is lean body mass, which includes muscle tissue, and everything else in your body that isn't fat (body water, blood, connective tissue, bone, and organs). Data from one of the biggest and newest studies, the STEP-1 trial, found that roughly 38 to 40 percent of weight lost was lean tissue.

This is about the same or slightly higher than what happens with calorie restriction alone. So semaglutide isn't uniquely worse for muscle than dieting, but rapid weight loss of any kind tends to take some muscle with it. That's why what you do alongside the medication matters so much.

Can You Lose Weight on Semaglutide Without Exercise?

You can certainly lose weight on semaglutide without exercising, but getting in your recommended 150 minutes of movement plus 2 or more days a week of strength training is best for weight loss and your health.

Clinical trials have found time and again that you can lose weight with semaglutide even without structured exercise programs because the appetite-suppressing effects are powerful enough to get results all on their own.

But if you're worried about losing muscle or keeping the weight off, skipping resistance training means you're more likely to lose a higher proportion of muscle during rapid weight loss. Over time, this can affect your metabolism, strength, and overall function. So while exercise isn't 100% necessary for the scale to move, it plays a pretty crucial role in shaping what kind of weight you lose and how your body will look and function afterward.

What About Semaglutide and Muscle Gain?

Gaining muscle while on semaglutide is challenging because you're typically eating fewer calories, and you need extra calories if you want to gain the most muscle. But research shows you can preserve muscle and potentially add some lean mass (especially if you're a strength training newbie), if you approach it strategically. Combining GLP-1 therapy with resistance training helps you keep more muscle, and in some cases, can lead to muscle gain compared to taking the medication alone.

If you want to keep or grow muscle during semaglutide therapy, here are some tips (according to research):

1. Eat adequate protein (at least 1.2 grams per kilogram of body weight daily)

2. Consider additional nutritional support, such as a quality whey protein to help you hit your protein targets, especially with low appetite when eating enough feels like a chore

3. Adding creatine to your routine can also support strength and muscle retention

If you're curious about how creatine stacks up against other supplements, check out this breakdown of creatine vs pre-workout.

Best Practices for Exercising on Semaglutide

If you're taking semaglutide, here's what the evidence supports for getting the best body composition outcomes.

Prioritize strength training

Resistance exercise is the single most effective tool for preserving lean mass during weight loss. Do resistance training regularly for at least 10 weeks, aiming for at least two to three sessions per week. Focus on compound movements like squats, deadlifts, presses, and rows. If you're new to lifting, start light and build gradually. 

Eat enough protein

Protein is your best friend when trying to hold onto muscle. Research recommends at least 1.2 grams per kilogram of body weight daily while on GLP-1 therapy. For someone weighing 180 pounds (about 82 kg), that's roughly 98 grams of protein per day at minimum. Spreading your intake across meals and snacks makes it easier to reach your target.

Consider creatine

Adding creatine to your routine can also support strength and muscle retention, and it pairs well with resistance training. If you're curious about how creatine stacks up against other supplements, check out this breakdown of creatine vs pre-workout.

Fuel your workouts 

Even with reduced appetite, you'll get better training sessions if you eat something beforehand. A small pre-workout meal or snack with carbs and protein can give you the energy to push through your lifts. On days when eating feels difficult, a pre-workout supplement can help with focus and performance.

Stay consistent

Combining pharmacotherapy with lifestyle changes yields better long-term outcomes for both body composition and sustained healthy weight compared to medication alone. The combination approach is where the real magic happens.

Takeaway

Semaglutide is a powerful tool for weight loss that works mainly by reducing your appetite rather than boosting your energy. Weight loss will include some muscle loss, similar to what happens with dieting alone. You can lose weight without exercise, but adding resistance training and prioritizing protein intake will help you keep more of your lean mass and support better long-term health. The research is clear that combining GLP-1 medications with strength training and adequate nutrition gives you the best shot at losing fat while holding onto muscle.

FAQs

Does semaglutide make you tired?

Semaglutide doesn't directly cause fatigue, but eating significantly less can leave some people feeling lower on energy, especially early in treatment. Ensuring you get enough protein and nutrients from the food you do eat can help maintain your energy levels.

How much muscle do you lose on semaglutide?

Studies show that about 20 to 40 percent of total weight lost on semaglutide is lean mass, including muscle. This is about the same as when you lose weight with other methods, like strict dieting. Resistance training can help minimize muscle losses.

What type of exercise is best while taking semaglutide?

Resistance training is the most effective exercise for preserving muscle during weight loss. Aim for at least two to three strength sessions per week. Cardio is fine to include for cardiovascular health, but lifting weights should be the priority if body composition is your goal.

Rachel MacPherson is a Nutrition Coach and health writer with over a decade of experience sharing science-backed information in the health and wellness space.

This article was reviewed by Rosie Borchert, NASM-CPT, for accuracy.