Weight reduction medicine have soared in reputation prior to now yr, serving to some lose dramatic quantities of weight — however not all that weight is fats. 

A few of that’s really lean mass, which is all the things within the physique that isn’t fats, together with your bones, organs and, importantly, muscle. 

“Once we take a look at weight discount from any intervention, about one-third of the load we lose tends to be lean mass, and that may be problematic,” stated Dr. Jaime Almandoz, an affiliate professor of inner medication within the Division of Endocrinology at UT Southwestern Medical Middle in Dallas. That lean mass loss is usually from muscle. “Lean mass is more healthy and related to higher metabolism, so after we lose lean mass, we could lose a few of that operate.”

The extra muscle mass an individual has, the higher the resting metabolic price, or the variety of energy an individual burns at relaxation. When an individual loses muscle mass, the resting metabolic price decreases, too.

“Should you can preserve your muscle mass, you might have extra sustained weight reduction as a result of your metabolic price wouldn’t be diminished,” stated Dr. Louis Aronne, director of the Complete Weight Management Middle at Weill Cornell Drugs in New York. 

Two medicine particularly have taken off for weight reduction: semaglutide and tirzepatide. Semaglutide is the drug present in Novo Nordisk’s Ozempic and Wegovy; tirzepatide is the drug in Eli Lilly’s Mounjaro. The medicines work in barely other ways, however each suppress urge for food, inflicting individuals to eat fewer energy.

Reducing weight has advanced results on the physique, particularly in the course of the preliminary phases. The extra weight an individual loses throughout a brief time period, the extra muscle mass they’ll lose along with fats, Almandoz stated.

When the physique isn’t getting as a lot power from meals, it pulls from reserves of power saved as fats and muscle, beginning primarily with fats. Whereas it’s regular for a few of this further power to be pulled from muscle, the physique might have to tug extra power from muscle if an individual is shedding a big quantity of weight shortly, similar to 5 to 10 kilos every week as a substitute of round 2 kilos.

“That’s why we attempt to emphasize sluggish, constant weight reduction slightly than fast weight reduction, the place you’re extra prone to pull out of your power shops” in muscle, stated Dr. Jonathan Purnell, an endocrinologist and professor of drugs on the Oregon Well being and Science College Knight Cardiovascular Institute in Portland.

“It’s additionally a operate of how low you go,” he stated. “When you enter into the wholesome BMI vary, you’re extra prone to be pulling from the lean shops.”

Why muscle mass is essential 

Regardless of considerations about muscle mass loss, on the finish of the dramatic weight reduction interval, individuals may very well have a more healthy physique composition, that’s, the ratio of lean mass — particularly muscle —in comparison with fats. 

“Whereas lean mass loss is regarding, on the finish, you may very well find yourself with a little bit extra lean mass in comparison with different parts similar to physique fats,” stated Almandoz, who has labored as a guide for Novo Nordisk and Eli Lilly. 

That’s essential as a result of “the injury from weight problems doesn’t come from elevated muscle, it comes from elevated fats mass, notably within the stomach,” in response to Aronne, who’s a guide for Eli Lilly. Determining the way to lose fats however not muscle could be the “holy grail” of weight reduction, he stated.

A 2021 scientific trial that examined the load loss results of Wegovy discovered that whereas about 40% of the load individuals misplaced tended to be lean mass, together with muscle, on the finish of 68 weeks, individuals who took the drug had a decrease danger of coronary heart illness and higher bodily operate in comparison with a placebo group.

“Though lean physique mass, which incorporates muscle mass, decreased in absolute phrases, the proportion of lean physique mass relative to complete physique mass elevated,” Allison Schneider, a spokesperson for Novo Nordisk, the maker of Wegovy and Ozempic, stated in an e mail.

Research confirmed comparable outcomes for the drug tirzepatide, which is bought below the model identify Mounjaro. In a part 3 scientific trial, “a discount in lean mass was reported at an analogous price as what’s seen in lifestyle-based therapies for weight problems,” Jessica Thompson, a spokesperson for tirzepatide-maker Eli Lilly, stated in an emailed assertion.

A brand new evaluation of knowledge from the identical trial discovered that after 72 weeks of taking the drug, about 25% of the load contributors misplaced was lean mass. Nonetheless, the contributors had an total more healthy physique composition. Aronne, who labored on the trial, offered the findings this week on the European Congress on Weight problems in Dublin. The evaluation has not but been printed in a peer-reviewed journal. 

The right way to preserve muscle mass when reducing weight

There are methods to mitigate lean mass loss throughout weight reduction, and folks older than 60 who’re already extra liable to muscle loss should be notably conscious of constructing muscle, stated Dr. Juliana Simonetti, co-director of the Complete Weight Administration Program on the College of Utah in Salt Lake Metropolis. 

A method is to be sure to’re consuming sufficient protein, which might be troublesome to do whereas utilizing weight reduction medicine. Protein is the constructing block of muscle; with out sufficient of it, muscle tissue aren’t capable of construct and restore themselves.  

Individuals ought to purpose to get 60 to 80 grams of protein daily, which might be troublesome to do by way of weight-reduction plan alone, Purnell stated. 

Simonetti stated she recommends on the lookout for protein dietary supplements, similar to protein powders, which might be low in sugar and have at the least 20 grams of protein per serving.

Train, particularly resistance coaching, can also be a vital a part of sustaining muscle mass throughout weight reduction, she stated. 

Complicating issues is that it’s troublesome to find out whether or not you’re reducing weight from fats or muscle with out particular tools. That’s why individuals on these medicine ought to keep in shut contact with their well being care staff, Simonetti stated. Should you’re reducing weight at a speedy tempo, you’re possible shedding muscle mass, as effectively. 

“Individuals ought to have a medical staff concerned after they use these medicine to allow them to monitor not solely muscle loss, but in addition kidney operate, salt and electrolytes,” all of which might be thrown off by dramatic weight reduction, she stated. Nausea — a standard aspect impact of weight reduction medicine — may point out acute kidney failure if an individual isn’t ingesting sufficient water, she added.

There are presently no tips for physicians counseling sufferers on weight reduction medicine. For now, many docs, together with Purnell, base their suggestions on tips for bariatric surgical procedure sufferers, because the weight reduction results of surgical procedure are akin to these seen with the brand new weight reduction medicine. 

Almandoz stated that because the medicine could cause dramatic weight reduction, physicians want research-backed suggestions about whether or not or not they need to inform individuals on the medicine to take further nutritional vitamins or different vitamins. It’s additionally unclear how these suggestions could also be totally different for older individuals. 

“There are a variety of unknowns with these medicines however we do know that they’re efficient and so they do convey metabolic advantages and enhancements in high quality of life,” he stated. Comply with NBC HEALTH on Twitter & Fb.