How To Stay Strong on a GLP-1

When a person sets a goal to lose weight, they are usually focused on losing adipose tissue, or body fat. However, it’s hard to shed body fat without also losing lean mass, which includes water and muscle.

Although they originated as diabetes medications, GLP-1 drugs like Wegovy (semaglutide) and Zepbound (tirzepatide) have proven to be highly effective for weight loss. In fact, studies have shown that people who use these drugs can achieve similar magnitudes of weight loss as people who undergo bariatric surgery. Therefore, many people who use GLP-1s lose more body fat and lean mass than they would if they lost weight with diet and exercise alone. 

Researchers are currently investigating whether using GLP-1s leads to a higher proportion of lean mass loss, but the available evidence suggests that people who lose weight while using GLP-1s can still maintain or even improve their muscle function. This is true even though they are losing some muscle mass alongside body fat. Nutrition and exercise are key to maintaining muscle.

Muscle mass vs. muscle strength

When it comes to muscles, we often associate strength with size. People who have overweight or obesity typically have bigger muscles, yet that doesn’t necessarily translate to greater functional strength.

Muscles are big bundles of fibers that work together to move a part of the body, but the individual fibers can vary quite a bit in quality. In addition, fat can infiltrate muscles, causing them to be weaker.

According to John Jakicic, an exercise physiologist at the University of Kansas, research has shown that people with obesity have more low-quality fibers in their muscles. However, a combination of weight loss and exercise can shift muscle towards higher quality fibers.

“Some of the loss may actually be a good adaptation from a health perspective,” he said.

Still, it’s important to remember that two people who begin using GLP-1s to lose weight may have very different starting points in terms of their muscle health. For example, people who are older or not very active are more likely to experience sarcopenia, which is the progressive and unintended loss of muscle mass and strength.

Because weight loss in general involves some reduction in muscle mass, an overly aggressive push to lose weight may make a person who is already at risk of sarcopenia more likely to develop it. Dr. Ian Neeland, a cardiologist at Case Western Reserve University, cautioned that in these scenarios, people should think carefully about using GLP-1s.

“That patient probably needs to be monitored much more closely and to think much more deeply about whether or not a GLP-1 is right for them,” he said.

Jakicic agreed that older adults should take steps to avoid losing muscle mass and other lean tissue mass. He also pointed out that weight loss plans and prescriptions aren’t set in stone. People can talk to their healthcare providers about making adjustments to their GLP-1 dosage and weight targets if necessary.

Do GLP-1s cause more muscle loss than other weight loss methods?

GLP-1 drugs slow digestion, causing people to feel fuller longer. Consequently, people who start taking GLP-1s may find themselves consuming a lot fewer calories than they had been before. In other words, GLP-1s can help people create the energy deficit that is necessary to lose weight.

“Many people will say that they may be somewhat more fatigued while taking these medications, and whether that’s from changes in the muscle or it has to do with them just not eating as much and having less fuel for the body, remains to be seen,” Neeland said.

Figuring out the unique effects that taking a GLP-1 may have on a person’s muscles is complicated because experts still don’t have an entirely clear picture of how weight loss in general affects the muscles.

Both Neeland and Jakicic said that people who voluntarily lose weight always lose some lean mass, which includes not just muscle, but also bone, water, organs, and anything else that is not adipose tissue.

Neeland was less certain when it came to putting an actual number on the proportion of lean or muscle mass lost during weight loss. He said that researchers studying weight loss may use different approaches for measuring a person’s body composition and may use the terms “lean mass” and “muscle mass” interchangeably. All of this makes it difficult to rigorously compare data from multiple studies.

Nevertheless, Neeland and his colleagues concluded that the available evidence suggests that the proportion of lean and muscle mass people lose while taking GLP-1s is in line with the proportion that people lose through diet and exercise alone, but called for additional research to confirm.

Some researchers and pharmaceutical companies are developing medications that would combine GLP-1 drugs with molecules designed to stimulate muscle growth. As scientists continue to push forward with new drugs and grapple with questions about what exactly these drugs are doing, Jakicic hopes that everyone remembers one important truth: “Muscle health is very different from muscle volume.” 

When voluntarily losing weight, the goal should not be to preserve muscle mass entirely, but rather to limit unnecessary muscle loss and improve muscle function. You should consult with your healthcare provider if you experience unexplained muscle pains, find yourself getting weaker, or start to have difficulty maintaining your balance. 

3 tips for keeping muscles strong and healthy

Regardless of whether you are trying to maintain your weight, slim down, or bulk up, the same basic principles for keeping your body healthy always apply. Everyone should consume a balanced, nutritious diet and exercise regularly.

However, people who are actively losing weight – especially those who are losing relatively large amounts of weight on GLP-1 drugs – need to be mindful of the amount of protein they are consuming and the amount of exercise they are getting.

1. Prioritize protein

Starting a GLP-1 tends to make you feel fuller faster, reducing the total number of calories you consume. Consequently, you may need to think more carefully about the nutritional content of your meals. In particular, you’ll want a greater share of the calories you consume to be protein.

Neeland said that the general rule of thumb is that people should eat around 1.2 grams of protein per kilogram of body weight per day (that’s about half a gram per pound of body weight). But for someone who is losing weight on a GLP-1, he said it’s a good idea to double that number. For example, that means someone who weighs 180 pounds would go from eating 90 grams of protein to eating 180 grams. 

For reference, both a serving of peanut butter and half a cup of beans contain about eight grams of protein. Meanwhile, lean meats and fish pack more protein in each serving, with a typical portion of chicken breast containing around 40 grams and a typical portion of salmon containing around 20 grams.

In terms of heart and metabolic health, it might be better to prioritize plant-based proteins by eating legumes, nuts, seeds, and grains when possible. However, it’s important to mix and match these foods to make sure you’re getting enough of each essential amino acid, which are protein building blocks that your body needs but cannot make on its own. 

People with diabetes will need to consider the fact that plant-based proteins like beans are often linked to carbohydrates. These foods are typically high in fiber, meaning they are less likely to cause big blood sugar spikes, but it’s still important to remember the amount of carbs they contain if you’re eating them more regularly.

Lean meats, fish, some dairy products, and eggs are excellent sources of protein as well.

2. Exercise more

The American Diabetes Association (ADA) recommends that adults get at least 2 hours and 30 minutes of moderate-intensity exercise per week. Moderate-intensity exercise causes your heart to beat faster but doesn’t prevent you from holding a conversation – for example, going for a brisk, 30-minute walk five times a week.

“For weight loss, people actually need a little bit more,” Neeland said. “About [3 hours and 45 minutes] a week of moderate-intensity physical activity is recommended for both sustaining and augmenting weight loss.”

In other words, our walking enthusiast would have to extend each of their five walks by an extra 15 minutes. A brisk walk is just one form of exercise, and Neeland advises people to mix up their workout plans. He usually tells his patients that about 75% of that exercise should be cardio and 25% should be resistance training. However, his recommendations change on a case-by-case basis; for some people, he thinks a little more resistance – around one third of the total – makes more sense.

Beyond that, he doesn’t really recommend specific exercises. Free weights, machines, resistance bands, and bodyweight exercises like pushups and squats are all great ways to build strength. The best workout plan is the one that you enjoy doing consistently.

Jakicic also pointed out that many exercises contain both cardio and resistance elements. For instance, most people would put riding an exercise bike in the cardio category, but to move the pedals, you have to push against resistance.

At the end of the day, everyone is starting from a different point in terms of fitness and strength, so what really matters is finding exercises that you can handle but will also push you.

3. Don’t neglect your other nutritional needs

Upping your protein intake is not a license to ignore the other macronutrients, especially fat and carbs, which your body still needs to run. Jakicic said there’s some wiggle room, but it probably makes sense for people losing weight on a GLP-1 to aim for 25% of their calories to be proteins, 25% to be fats, and 50% to be complex carbohydrates (whole grains, vegetables, fruits, and nuts, not simple sugars like candy and soda).

Jakicic also pointed out that people who eat less while they are taking a GLP-1 may be setting themselves up for certain nutritional deficits if they aren’t paying close attention to what they’re eating. 

“When we’re eating less, aren’t we taking in less vitamin C, less vitamin D?” he said.

It’s always a good idea to get vitamins and minerals from foods such as fruits and vegetables when possible, but Jakicic also recommended a daily multivitamin for people who are taking GLP-1s.

Finally, Jakicic pointed out that many people drink water and other beverages during meals. So, if someone is having fewer meals or smaller meals, then they may also be hydrating less as a result. Water is essential to keep your digestive system functioning properly and to help your body flush out all the byproducts that will build up from breaking down body fat. 

Not everyone’s hydration needs are the same, so it might be a good idea to discuss intake targets with a healthcare provider if you are worried about how much you are drinking.

The bottom line

By slowing your digestive tract and reducing your hunger, GLP-1 drugs can cause you to lose weight. These drugs can be much more effective than diet and exercise alone, so people who use them are more likely to see bigger reductions in their body fat and their lean mass, including their muscle mass. It’s important to start thinking about strategies for preserving muscle strength right when starting a GLP-1, even before weight loss occurs.

For some people who are particularly vulnerable to sarcopenia, it is important to be cautious when using GLP-1s to avoid too much loss of muscle mass. However, the current evidence suggests that most people can maintain their muscle health while using GLP-1s to lose weight – provided they maintain proper nutrition and exercise regularly.

Learn more about GLP-1s here:

• Dealing With Unexpected Effects of GLP-1s
• Tips for Weight Loss Medications When You Have Diabetes
• 7 Tips for Navigating Nausea on a GLP-1 Medicine