5 Fitness Habits That Matter Most While Taking GLP-1s

GLP-1 medications may be helping people lose weight, but fitness expert, nutrition coach and AND/life founder Andrea Marcellus says they’re also changing the way many people approach exercise. Known for her practical “in-the-moment” workout approach and wellness strategies for busy professionals, Marcellus says one pattern has become especially clear: once the scale starts moving, workouts often fall to the bottom of the priority list.

“Many people are seeing results without exercising consistently, so movement gets deprioritized altogether aside from occasional walking,” Marcellus says. “By the time some clients come to me, they’ve already plateaued despite increasing dosages.”

While medications such as semaglutide and tirzepatide can be highly effective for weight loss, Marcellus says quick changes on the scale do not always mean healthier body composition. Ahead, find five trainer-approved tips for preserving muscle and supporting overall health while taking these medications.

Prioritize strength training

“The people who tend to have the best long-term results are the ones using GLP-1s alongside a sound nutrition and workout plan,” Marcellus explains. “When protein, fiber and muscle-building remain priorities, they’re much more likely to preserve lean muscle and improve body composition, even if the weight loss happens more gradually.” She recommends strength training at least three times a week to help maintain muscle and avoid some of the body-composition changes that can come with rapid weight loss.

Don’t overlook protein and nutrition

One of the biggest mistakes GLP-1 users make is assuming that eating less automatically means eating well, says the fitness expert. Since the medications suppress hunger and can affect appetite and blood sugar regulation, many people end up eating far less without realizing they are also missing key nutrients. “Without enough protein, antioxidants, omega-3s, fiber and prebiotics and probiotics, people can experience rapid muscle loss, hair shedding, skin changes and gastrointestinal issues,” she says.

Add interval training

Marcellus also recommends adding interval training a few times a week rather than relying solely on long, steady-state cardio. Short bursts of higher-intensity movement paired with strength training can help maintain energy and muscle as the body changes. “People don’t need to spend hours working out to see benefits,” Marcellus says. “It’s more about consistency and making sure your workouts are actually helping you maintain strength and function while your body is changing.”

She adds that balancing resistance training, cardio and recovery-focused movement tends to create better long-term results.

Move more throughout the day

Structured workouts matter, but Marcellus says movement outside the gym is just as important. Walking more, standing throughout the day and avoiding long stretches of inactivity can make a bigger difference than people realize. “Energy and mood can suffer too,” she notes, especially when movement and nutrition are lacking.

Treat GLP-1s like a tool, not the whole solution

Muscle loss is about much more than aesthetics. Lean muscle helps support metabolism, blood sugar regulation and long-term weight maintenance, which is why preserving it matters during weight loss. “GLP-1s should be treated like a booster, not an all-in-one solution,” Marcellus says. “These medications can absolutely benefit people dealing with obesity and chronic health conditions, but they work best when they’re paired with lifestyle changes that support overall health and well-being.”