As Americans increasingly use GLP-1 medications, preserving strength and mobility has become an important concern with age. The drugs have been linked to loss of lean muscle, especially during rapid weight loss, but several practical habits can help people protect their strength.

Jacob Zemer, a fitness coach in New York who primarily trains clients from 35 to 55 years old, said adults can lose muscle for several reasons. Beyond GLP-1 use, he pointed to major changes in daily routines.

"The biggest change is lifestyle," Zemer told Fox News Digital. "When you're in your teen years or your 20s, you're running around, you're doing activities that lend themselves to building muscle."

That activity can decline as people turn their attention toward careers and families. Zemer said becoming more sedentary lowers both metabolism and activity levels, contributing to reduced muscle.

"You simply become more sedentary, which lowers your metabolism and your level of activity, so you're going to have less muscle," he said.

Hormone levels also begin changing for men and women as they approach their 40s, according to Zemer. He said the body increasingly directs calories toward fat storage rather than using them for protein and muscle building.

Zemer believes people should remain mindful of building muscle from a young age. He compared muscle developed through the 50s to a 401K that people will gradually draw from during their 60s, 70s and 80s.

Protein is one of the coach’s four central strategies. It helps stimulate muscle protein synthesis, the process through which the body repairs and builds muscle, and sufficient dietary protein can reduce the risk of sarcopenia, the age related loss of muscle mass and strength.

Protein requirements vary depending on a person’s age, activity and goals. Zemer said sedentary people do not need to become obsessed with protein, but those who regularly train at a gym can benefit from consuming 0.8 to 1 gram per pound of body weight.

Strength training is another key tool for preserving muscle. The U.S. Physical Activity Guidelines recommend that adults train all major muscle groups at least two days each week, including the legs, hips, back, abdomen, chest, shoulders and arms.

The Centers for Disease Control and Prevention advises exercising at moderate or greater intensity until completing another repetition with good form becomes difficult. The guidelines also call for 150 to 300 minutes of moderate intensity aerobic activity or 75 to 150 minutes of vigorous activity each week.

Even relatively brief sessions can help maintain existing muscle, according to Zemer. "Even if you have a busy week, and you went to the gym and you lifted weights 30 minutes twice a week, that may not be enough to build new muscle , but that is certainly enough to maintain muscle," he said.

Beginners can focus on basic functional movements rather than complicated routines. Squats, lunges, pushups and pulling movements can support strength used in daily activities, while carrying weighted objects in a farmer’s carry can improve grip, balance and overall stability.

People who feel intimidated by a gym can work with a qualified trainer for a few sessions, Zemer said. That assistance can help improve technique and give newcomers greater confidence.

Quality sleep is perhaps the most difficult strategy, with Zemer recommending seven to nine hours. "Now, if you don't get that every night, you're not going to lose muscle," he noted. "But when you start to look at actual serious sleep deficiency, like we're talking five hours consistently, that is when you see rapid muscle loss."

Regular movement also matters, including for people who are not following structured workout programs. Zemer cautioned that sedentary behavior is associated with rapid declines in muscle mass and strength, while continuing to move can help slow age related muscle loss.

"The worst thing you can do, even if you're injured, is to stop doing anything," Zemer said. He urged people to find activities they can still perform, even when something hurts or their knees no longer feel as they once did.

These habits are especially important for people using GLP-1 medications for weight loss, Zemer said. Without adequate protein or strength training, the drugs can contribute to muscle loss along with accelerated fat loss.

"If you are on a GLP-1, just remember you're accelerating the rate of fat loss, but you're also accelerating the rate of lean muscle," he said. "You want to make sure you're getting that protein and training, so that you are not losing muscle on top of the fat loss."