Scientists have developed a pill to help people grow muscle. The tablet encourages fat burning and was found to boost leg muscle strength and power by 13% in an eight-week trial. Experts hope that if this result is repeated in larger trials the drug could be taken alongside weight loss jabs to minimise muscle wastage.
How the pill works
The pill developed by Swedish biotech firm Atrogi mimics the metabolic effect of exercise in skeletal muscle, which are those attached to bones that power body movement, posture and stability. Skeletal muscle makes up around 40% of our body mass and the pill called ATR-258 stimulates metabolism, encourages fat burning and preserves or builds lean muscle mass rather than wasting it during weight loss.
The ATR-258 pill contains a small molecule that binds to beta-2 adrenergic receptors located in skeletal muscle. It moves a protein called GLUT4 directly to the cell membrane without needing insulin, lowering blood glucose levels.
Trial results
The first human proof-of-mechanism trial examined the effects of ATR-258 in 13 overweight or obese subjects. It was well tolerated and resulted in average reductions of 1.1kg in fat mass and increases of 0.8kg in lean mass.
Paul Little, chief executive officer at Atrogi, added: "These results are a major step forward … We now have human data pointing to a unique profile in metabolic health where muscle becomes medicine."
Prof Morten Hostrup, principal investigator of the study, said: "What struck me most was the magnitude of the signal in lower-extremity power. Having worked extensively with classical β2-agonists, I know they can enhance power, but not to the extent we observed here. These findings give us a genuinely intriguing signal about the role of GRK2-biased signalling in muscle physiology, and a strong rationale for taking ATR-258 forward into larger clinical trials."
Impact on weight loss jabs
It comes as blockbuster weight loss injections which can see users lose up to a fifth of their body weight have been criticised for wasting muscle. Recent data shows up to 45% of weight lost can be muscle mass. Often users have to stop taking the appetite-suppressing injections due to cost or side effects and can pile fat back on, but never regain muscle mass. This can make it harder to lose the weight again and lead to frailty.
Professor Tore Bengtsson, chief scientific officer at manufacturer Atrogi, said: "These first clinical data give us important confidence that our approach is translating. To see fat loss alongside an increase in lean muscle mass and improvement in muscle function represents a truly differentiated profile, and is highly encouraging. Beyond muscle-sparing weight loss, we believe this mechanism also warrants investigation in sarcopenia and rare diseases marked by substantial muscle loss and weakness."
Weight loss injections that mimic the hormone GLP-1 to make people feel full sooner have been heralded as a way to tackle Britain's obesity epidemic. However without proper support users end up losing vital bone and muscle mass. Transforming users' lifestyles to eat a diet rich in good quality protein, fruit and vegetables is key, as well as doing exercises such as lifting weights to maintain muscle mass.
