For many people, the biggest concern about weight loss is the potential loss of muscle mass. While you want to eliminate excess weight, you still want to preserve your muscle. Sometimes regular exercise and dietary adjustments alone aren’t enough for significant weight loss in a certain timeframe, which is why weight loss drugs have become widely popular. They help you lose weight, but do they reduce muscle mass at the same time? You’ll find out below.

Can weight loss drugs reduce muscle mass?

Weight loss drugs decrease appetite and slow down emptying of the stomach, making you feel less hungry. But weight loss doesn’t include the reduction of adipose (fat) tissue only. You may also lose muscle mass. About one-third of the weight you lose from any intervention accounts for lean mass. The term lean mass refers to everything in your body that isn’t fat, e.g., your bones, organs, and muscles. However, the loss of lean mass from weight loss interventions involves muscles primarily. Basically, weight loss interventions such as diet, exercise, or weight loss drugs can lead to loss of muscle. This is problematic because muscle mass is necessary for healthy metabolism. By losing lean mass, you may lose some of that function in the process too.

Popular weight loss drugs such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) can reduce muscle mass. Although these drugs have different mechanisms of action, they both suppress appetite. As a result, your calorie intake decreases, which is why you keep losing weight. This is particularly important for people who tend to overeat. However, the more weight you lose in a short timeframe, the more fat and muscle you lose.

Why does this happen? Well, when your body doesn’t get enough energy from nutrition, it targets reserves of stored fat and muscle. It starts with fat first. If you’re losing weight quite fast (5 to 10 lbs instead of 2 lbs), the body may pull higher amounts of energy from your muscles. As a result, your muscle mass keeps decreasing.

What does research say?

A STEP1 (Semaglutide Treatment Effect in People with Obesity) clinical trial from The New England Journal of Medicine found that 40% of weight people lose with Wegovy accounts for lean mass, including muscle. In this research, scientists relied on a DEXA scan to assess the body composition of participants. Losing 40% of lean mass, particularly muscle, is too much and shows why it’s important to take this subject into consideration when thinking about using weight-loss medications.

A different study, published in Diabetologia, also involved a DEXA scan and found that participants experienced a 40% reduction in lean mass. More precisely, both studies found that weight loss drugs such as semaglutide lead to a significant reduction in lean mass i.e. muscle loss.

When does muscle loss become bad?

Loss of muscle mass isn’t always bad because your overall body composition can improve (because you’re also losing body fat), and you may still have a better ratio of lean mass compared to adipose tissue. It can become bad, though. That happens when you start losing weight rapidly, and the loss of muscle mass becomes excessive. 

Some weight-loss drugs like Ozempic lead to rapid weight loss. Quick weight loss may seem amazing because you see instant results in the mirror, but it can lead to a reduction in muscle mass and bone density. These effects are particularly emphasized when people use weight-loss drugs alone, without combining them with exercise and proper nutrition. Rapid weight loss from drugs such as Ozempic could contribute to sarcopenia, the age-related progressive loss of muscle mass and strength. While sarcopenia is common with the aging process, quick weight loss can speed up this process.

How do we know the extent of muscle loss with weight-loss drugs?

You’re taking weight-loss drugs, or thinking about it, and want to know how much muscle you lost in the process? The easiest way to find out is to take a body composition test. The dual-energy X-ray absorptiometry (DEXA) scan stands out as one of the most accurate and easiest tests that measure body composition.

In a nutshell, the DEXA scan uses low-dose X-ray beams at different frequencies to scan your body while you’re lying on the table. Different frequencies allow DEXA to scan your adipose (fat) tissue, muscles, and bones accurately. The whole process lasts 10 to 15 minutes or until the machine captures a clear image.

When you do a DEXA scan at Fitnescity, you also get access to a personal dashboard where all results are displayed and explained. You can also see how your results compare to other people within the same age group. The results show body fat percentage, fat-free mass i.e., lean mass, muscle mass in arms and legs, and more. That way, you can get a detailed insight into your muscle mass, and adipose tissue, and track progress.

How to lose weight without losing muscle

Although weight-loss drugs can contribute to muscle loss, it’s useful to know it doesn’t have to be that way. There’s a lot you can do to lose weight without reduction in muscle loss, such as:

●      Modify your diet: one of the biggest mistakes is that people often rely on weight-loss drugs to do all the work, without making adjustments in their nutrition. However, simple tweaks in your diet can go a long way. Evidence confirms that higher protein intake can reduce muscle loss in people who are losing weight. That’s why it’s important to prioritize healthy nutrition when you’re on a weight loss journey. Increase consumption of protein, fiber, fruits, vegetables, nuts, seeds, and healthy fats. Reduce intake of sugary foods, trans fats, too much salt, heavily processed and refined foods, and other items that are high in calories and low in nutritional value. By optimizing your nutrition, you can avoid significant reductions in muscle mass.

●      Exercise regularly: in addition to modifying your diet, you should also exercise regularly, even if you’re taking weight-loss drugs. Cardio training is the best type of physical activity for losing fat, but preserving muscle mass calls for resistance or strength training. One meta-analysis revealed that resistance training can mitigate muscle loss that occurs during caloric restriction. Resistance training preserves muscle so that you’re losing fat instead of muscle mass. Plus, it speeds up your metabolism and improves mobility.

●      Get enough sleep: simple lifestyle adjustments mean a lot for body composition. In order to preserve muscle mass, even when using weight-loss drugs, it’s crucial to get more sleep. Lack of sleep increases stress and appetite thus increasing calorie intake. Good night’s rest supports muscle recovery after workouts, balances your hormones, prevents overeating, and exhibits beneficial effects on muscle strength. Strive to get 7 to 9 hours of sleep every night.

Conclusion

Weight loss drugs can help with weight loss, but they may also cause muscle loss in the process. Reduction in lean mass is quite problematic when you’re losing weight rapidly. The best thing to do is to track body composition, adipose tissue, and lean mass percentage with a DEXA scan at Fitnescity. With DEXA scan, you can monitor muscle mass and how it responds to weight loss drugs, which allows you to modify your lifestyle accordingly.

References

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3661116/

https://www.nbcnews.com/health/health-news/weight-loss-drugs-muscle-loss-rcna84936

https://www.nejm.org/doi/full/10.1056/NEJMoa2032183

https://link.springer.com/article/10.1007/s00125-019-05065-8

https://www.healthline.com/health-news/ozempic-muscle-mass-loss

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4892287/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946208/