Opinion:
According to a survey published by RAND, approximately 12% of Americans had used a GLP-1 for weight loss as of August 2025. Another 14% said they were interested in trying them in the future. Nearly one quarter of the American population has taken, or is interested in using, these medications.
While originally approved by the FDA for the treatment of diabetes and related issues, some physicians are now prescribing GLP-1 for weight loss. The number of prescriptions for GLP-1s has more than tripled since 2020 with 50 to 64 being the age group with the highest usage.
For a variety of medical reasons beyond the scope of this article, GLP-1s can reduce appetite and food intake, and this often produces weight loss. The choice to take GLP-1s is a private decision between people and their medical provider, and I do not offer any opinions pro or con on that question. In this month’s article, I will discuss important fitness strategies if you do choose to use GLP-1s after discussion with your doctor.
Rapid weight loss can also lead to loss of fat-free mass like muscle.
According to a study done at the University of Virginia, when people lose weight on GLP-1s, about 25 to 40 percent of the loss comes from fat-free mass. This can mean the loss of muscle and other healthy tissue. This can potentially have negative long-term impact on strength, metabolism, ability to perform daily tasks, posture and other issues that impact people’s quality of life. People typically lose about 8% of fat-free mass per decade through their life, so the rate of fat-free mass loss is much higher when someone is on GLP-1s than what most people experience with typical aging.
It is important to note that nearly any rapid weight loss will cause a loss of fat-free mass. That means the recommendations in this article would also apply to all forms of rapid weight loss.
Strength training is the best exercise to preserve and build muscle while on GLP-1s (or at any time).
According to Harvard Medical School, strength training two to three times per week is the best way to build strength and muscle. Strength training can be done with traditional weights, exercise machines and even rubber bands designed to increase strength. Workouts should focus on the entire body: chest, back, arms, shoulders, legs and calves. Harvard recommends doing 10 repetitions per set, with good form as a starting point. Over time, you might increase your weights and decrease the repetitions to between six and eight for some workouts. If done consistently over time, strength training two or three times per week is the best strategy for retaining muscle while using GLP-1s. I always recommend getting professional instruction and a doctor’s approval before starting a strength-training program.
Possible special physical concerns with strength training while on GLP-1s may include possible side effects like nausea, especially at the outset of taking the medication. Some medical experts recommend initially starting a little lighter with your weights for this reason. It is usually a good idea for anyone to start with somewhat lighter weights to give your entire body and all its systems some time to adapt to the new challenge of strength training. This is especially true while taking a GLP-1.
Protein is important, too.
Adequate protein intake is another important GLP-1 fitness strategy. As calories reduce, it becomes more important than ever to be intentional about adequate protein intake, because protein is the most important macronutrient for retaining muscle. Due to the potential increased fat-free mass loss with quick fat-loss approaches (including GLP-1s), protein becomes more important than ever. The Cleveland Clinic recommends 20 to 30 grams of protein per meal while taking GLP-1s. While daily recommendations can vary, most experts encourage aiming for 0.5-0.9 grams of protein per pound of body weight. That means a 160-pound person should aim for 80 to 144 grams per day. Great sources of protein include chicken breast (26 grams in three ounce serving), soybeans (about 15 grams per half-cup serving), salmon (20-25 grams in three ounce serving) and Greek yogurt (around 19 grams per serving). Protein exists in more foods than we realize, so it can be good to use an app to track your intake and find out how much you are actually eating.
Jeff Blair (M.S., CSCS) is a Certified Personal Trainer with over 23 years’ experience. He founded the
SoCalSport Personal Training Studio in 2012. Contact him jeff@socalsport.com for article feedback.
By Jeff Blair