Sarcopenia: what it is, treatment and what peptides show

What is sarcopenia and how many people does it affect?

Sarcopenia is a muscle disease (muscle failure) rooted in adverse muscle changes that accrue across a lifetime; it is common in older age but can also occur earlier. The revised European consensus (EWGSOP2) defines it by low muscle strength as the key characteristic, confirms the diagnosis by detecting low muscle quantity or quality, and treats poor physical performance as indicating severe sarcopenia¹. It has had its own ICD-10-CM code (M62.84) since 2016⁵.

How common it is depends on the definition. A systematic review of 263 eligible studies (151 in the meta-analysis, 692,056 participants, mean age 68.5 years) found that the prevalence of sarcopenia varied between 10% and 27% depending on the classification, cut-off points and measuring instrument, and that of severe sarcopenia between 2% and 9%². The international ICFSR guideline cites roughly 6% to 22% of older adults³. A Lancet review summarizes the clinical picture and biology of the disorder⁶.

It is not a minor diagnosis. In a review of 17 prospective studies using the European definition, sarcopenia was associated with higher mortality (pooled odds ratio 3.60; 95% CI 2.96 to 4.37) and functional decline (odds ratio 3.03; 95% CI 1.80 to 5.12), and with more falls and hospitalizations, although data on fractures were less clear⁴.

Symptoms and diagnosis: how sarcopenia is recognized

Symptoms are functional: slow walking, difficulty rising from a chair, weak grip and falls. The ICFSR guideline recommends rapid screening with gait speed or the SARC-F questionnaire, followed by diagnosis with an internationally accepted tool such as the EWGSOP or FNIH definitions³.

The European algorithm starts from strength: handgrip below 27 kg in men and 16 kg in women is considered low. If strength is low, the diagnosis is confirmed by measuring muscle quantity or quality (for example, dual-energy x-ray absorptiometry), and if physical performance is also poor (gait speed of 0.8 m/s or less) it is rated severe¹. The FNIH group proposed cut-points based on handgrip strength and appendicular lean mass⁷, the Asian group (AWGS 2019) published its own update⁸, and a US consortium (SDOC) published position statements on the definition and outcomes⁹. Having several definitions is why prevalence figures do not match.

Standard treatment today

The international ICFSR guideline strongly recommends resistance-based physical activity and conditionally recommends protein supplementation or a protein-rich diet. It made no recommendation on vitamin D supplementation or on prescribing anabolic hormones, and noted a lack of robust evidence for other options³.

A meta-analysis of resistance training in older adults supports its effect on muscular strength¹⁰, and another meta-analysis found that protein supplementation augmented the adaptive response of skeletal muscle to resistance training¹¹. The PROT-AGE group published evidence-based recommendations on dietary protein intake in older people¹².

Weight loss in older adults shows why exercise matters. In a one-year randomized trial of 107 obese adults aged 65 or older, body weight fell 10% with diet and 9% with diet plus exercise, but lean mass fell 5% in the diet-only group versus 3% in the diet-plus-exercise group, and physical function improved more with the combination (21% versus 12% with diet and 15% with exercise alone)¹³.

What research on peptides and related agents has shown

It is worth being clear from the start: no peptide is approved to treat sarcopenia, and most studies measured body composition, not function. What follows describes what was observed in each family. More context in Growth hormone secretagogue guide and The secretagogue and IGF-1 debate.

Growth hormone (GH). It is not a secretagogue but the hormone itself, yet it is the benchmark for that family. In a double-blind trial of 52 healthy men older than 69 with low IGF-1, six months of GH increased lean mass 4.3% (versus a 0.1% decrease with placebo) and reduced fat mass 13.1%, but there were no differences in knee or handgrip strength or endurance, and adverse events were more frequent (48 incidents versus 14); 26% of those treated needed a dose reduction¹⁴. A systematic review of 31 articles (18 populations; 220 treated participants completing the studies) found a lean-mass gain of 2.1 kg and a fat-mass reduction of 2.1 kg, with more edema, arthralgias, carpal tunnel syndrome and gynecomastia, and somewhat more diabetes and impaired fasting glucose; its authors concluded that GH cannot be recommended as an antiaging therapy¹⁵. Combined with testosterone for 16 weeks in 122 men aged about 70, GH appeared to enhance the gains in lean mass and strength produced by testosterone, with rises in blood pressure¹⁶.

MK-677 (ibutamoren), not a peptide. It is an oral ghrelin mimetic that activates the same receptor as peptide secretagogues. In a two-year randomized trial of 65 healthy adults aged 60 to 81, 25 mg daily raised GH and IGF-1 to young-adult levels. At one year, fat-free mass increased 1.1 kg with MK-677 versus a 0.5 kg decrease with placebo (P < 0.001), but strength and function did not change; fasting glucose rose 5 mg/dL and insulin sensitivity decreased. The authors noted the study was underpowered for functional end points¹⁷.

Tesamorelin. It is a GH-releasing hormone analog. In a trial of 412 patients with HIV and abdominal fat accumulation, 26 weeks of tesamorelin reduced visceral adipose tissue by 15.2% (versus a 5.0% increase with placebo) and raised IGF-1 by 81%¹⁸. The FDA label indicates EGRIFTA SV for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy, states that it is not indicated for weight management, and that long-term cardiovascular safety has not been established¹⁹. The sources consulted did not show a tesamorelin trial in sarcopenia. See Tesamorelin: the approved GHRH analog.

Ghrelin, sermorelin, ipamorelin and other secretagogues. Ghrelin was described in 1999 as an acylated peptide from the stomach that releases growth hormone²⁰. For ipamorelin, the only human trial that turned up in the search was a proof-of-concept study in postoperative ileus, not muscle²⁷. The sources consulted did not show randomized trials of sermorelin or ipamorelin in sarcopenia, so their effect on muscle in older people is today a hypothesis, not a finding.

Anamorelin (cachexia). It is an oral ghrelin-receptor agonist, not the natural peptide, and its evidence is in cancer cachexia, a neighboring condition in which sarcopenia is one of the defining criteria²⁸. In ROMANA 1 and 2 (979 patients with non-small-cell lung cancer), lean mass increased 0.99 and 0.65 kg with anamorelin and fell 0.47 and 0.98 kg with placebo, with no difference in handgrip strength²¹. The 2020 ASCO guideline recommends no specific drug as standard²². Japan approved it in January 2021 for cancer-associated cachexia²³, and the EMA refused authorization in 2017 for a marginal effect on lean mass and no proven effect on strength or quality of life²⁴. Detail in Cancer cachexia and anamorelin.

GLP-1 drugs: the reverse question. GLP-1 agonists are not studied to gain muscle but for the opposite question: how much is lost when weight falls. A 2024 review notes that the share of weight loss that is lean mass ranges from 40-60% in some studies to about 15% or less in others, that lean mass includes organs, water and bone as well as muscle, and that MRI studies suggest skeletal muscle changes are adaptive and commensurate with what is expected for age, disease and weight lost. Still, it warns that older age and disease severity may influence candidate selection because of sarcopenia risk, and that drugs to pair with GLP-1 therapies to preserve muscle are under development²⁵. See GLP-1s: muscle, rebound, eyes and pancreas.

Bimagrumab (antibody, not a peptide). It blocks activin type II receptors. In a trial of 180 people aged 70 or older with sarcopenia, 6 months of bimagrumab increased lean mass 7% versus 1% with placebo (P < 0.001), but the improvement in the Short Physical Performance Battery (1.34 versus 1.03 points; P = 0.13) and in gait speed was not significantly different from placebo; both groups received adequate diet and home exercise, and several authors were employees of the manufacturer²⁶.

Safety: adverse effects and precautions

Safety signals depend on the agent. GH in older people produced edema, arthralgias, carpal tunnel syndrome, gynecomastia and more diabetes or impaired glucose¹⁵; with MK-677, fasting glucose, cortisol, appetite, mild edema and muscle pain increased and insulin sensitivity decreased¹⁷. The tesamorelin label warns that long-term cardiovascular safety has not been established¹⁹. In ROMANA 1 and 2 the most frequent grade 3-4 event with anamorelin was hyperglycemia, in under 1% and 1% of patients²¹. With GLP-1 drugs, the risk is lean-mass loss during rapid weight loss, which resistance exercise attenuates in older adults¹³²⁵.

Summary by agent

Frequently asked questions

What is sarcopenia? It is a muscle disease defined by low muscle strength, confirmed by low muscle quantity or quality; if physical performance is also poor, it is considered severe¹.

Is any peptide approved for sarcopenia? Not in the sources consulted. Tesamorelin is indicated only for excess abdominal fat in HIV lipodystrophy¹⁹, and anamorelin is approved in Japan for cancer cachexia, not sarcopenia²³.

What do guidelines recommend for treating it? The ICFSR guideline strongly recommends resistance-based physical activity and conditionally recommends a protein-rich diet or protein supplements; it makes no recommendation on anabolic hormones³.

Does growth hormone improve strength in older adults? In the trial of 52 men it increased lean mass 4.3% but did not improve strength or endurance, and the 2007 review concluded it cannot be recommended as an antiaging therapy¹⁴¹⁵.

Do GLP-1 drugs make you lose muscle? Some lean mass is lost with weight loss; in some studies it is 40-60% of weight lost and in others about 15% or less, and MRI studies suggest muscle changes are commensurate with what is expected²⁵. In older adults with obesity, adding exercise to dieting reduced lean-mass loss from 5% to 3%¹³.

How many people have sarcopenia? It depends on the definition: between 10% and 27% in a review of 151 studies, and between 2% and 9% for the severe form².