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Do GLP-1s cause muscle loss?

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Now that more Americans are taking GLP-1s such as Ozempic® and Wegovy®, health care experts are now turning attention to how these medicines impact muscles. Novo Nordisk and Eli Lilly, the pharmaceutical companies that manufacture popular drugs used for weight loss, are actively pursuing combo treatments, according to news reports. And clinicians who prescribe these drugs instruct patients to exercise—a no-brainer part of any weight loss plan—but the difference is that providers are now strongly encouraging resistance training, not just calorie-burning cardio.  

A little background: GLP-1s are a class of medications FDA-approved to treat either type 2 diabetes, heart disease, or obesity. These medications mimic your natural GLP-1 hormone and help regulate blood sugar levels by increasing insulin secretion after you eat. 

Muscle mass is a key player in resting energy expenditure (the number of calories you burn at rest). Research suggests that muscle plays a role in long-term weight management. Specifically, more skeletal muscle is associated with less sugar in the blood—a good thing, because high blood sugar levels can increase the risk of diabetes. So how does GLP-1-related muscle loss happen? How does that compare to muscle loss from other weight loss methods? And what can you do to minimize it? 

What happens to muscle when you lose weight?

When people lose weight, regardless of the weight loss method, they lose both lean and fat mass. Lean mass is the weight of everything except fat—your muscles, bones, ligaments, tendons, and organs. Modest calorie cutting can cause your body to break down not only fat, but also skeletal muscle. In fact, research suggests cutting calories can lead to a 25 to 33 percent loss in lean mass.

Does GLP-1 muscle loss occur?

So far, the direct effects of GLP-1 medications on skeletal muscle have only been researched in rodents. However, the research suggests that GLP-1s can have protective effects on muscle or increase skeletal muscle. For example, GLP-1s can improve muscle loss in mice by impacting the pathway that inhibits muscle loss (which may be beneficial for muscle loss diseases), according to a study published in the Journal of Cachexia, Sarcopenia and Muscle. 

Most weight loss from GLP-1s appears to come from losing fat. The loss of lean mass across some studies on GLP-1s was consistent with other weight loss methods such as bariatric surgery and dieting according to a review published in EnM: Endocrinology and Metabolism. GLP-1 medications can also slow digestion, which may help you feel fuller faster, so you eat less. Since people taking GLP-1s tend to eat fewer calories overall, their muscle loss can look similar to those who cut calories.

On that note, perhaps GLP-1 medications don’t directly contribute to muscle loss. Instead, other factors—including calorie restriction, age, other medications, medical conditions like type 2 diabetes, and lack of movement—may be at play. Either way, it’s possible to protect muscles—and the metabolism—while losing weight. 

How to preserve muscle mass during weight loss

Eat more protein

A high-protein diet can help protect you from GLP-1-related muscle loss, according to a scientific review published in Advances in Nutrition. Eating high protein alone doesn’t increase muscle but it does support building new muscle. A high-protein diet will vary for each individual, but in general, it’s defined as 20 percent or more of your total daily calories coming from protein. Some high-protein foods include seafood, poultry, beef, eggs, beans, and soy.

Stay active and build muscle 

Add strength training into your routine because research suggests that endurance and resistance training can help protect your muscles during weight loss. Research also shows that exercise may help preserve or improve lean mass while losing weight. This is good because maintaining muscle mass during weight loss may also protect your resting metabolism and reduce the risk of regaining body fat.  It may also prevent sarcopenia—or age-related muscle loss. 

Lose weight slowly

We know it’s tempting to dive right in and see results quickly. But take your time on your weight-care journey. Studies show that extreme calorie cutting that causes rapid weight loss increases your chance of muscle loss while losing weight. It’s better for you, your muscles, and your metabolism to lose weight slowly and steadily.

Bottom line: Managing GLP-1 muscle loss 

GLP-1 muscle loss is no different than other weight-loss methods such as dieting, bariatric surgery, or other medications, and you can slow or minimize muscle loss when losing weight. There isn’t enough scientific evidence to support that GLP-1s alone cause muscle loss. But if you’re concerned about muscle loss or other side effects from taking GLP-1s, talk to your health care provider. GLP-1 medications do have other common side effects, including nausea, vomiting, diarrhea, and acid reflux. More serious but less common side effects include pancreatitis, gallbladder disease, and worsening of diabetic eye disease. Those with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasias should not use these drugs. Find detailed side effect and risk information for specific medications on our dedicated medication page.

*While GLP-1s are effective for weight loss, they are not clinically appropriate for everyone. Eligibility for a GLP-1 is based on a thorough evaluation of medical history, eating behavior, lab work, and insurance coverage. If a GLP-1 is not appropriate, Found affiliated providers work to determine if another safe, effective medication is.

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