Press release · For immediate release

Weight-loss drugs take muscle with the fat. This UK clinic just became the first to watch it happen live.

London, 15 June 2026. Heracles Health switches on real-time muscle monitoring for its patients, powered by LeanShield from ParrotPal Group.

At a glance

  • Heracles Health becomes the first UK clinic to give clinicians a continuously updated muscle-safety score for every weight-loss patient
  • The system, LeanShield from ParrotPal Group, turns daily food, training and weight logs into a live 1 to 100 score, monitoring muscle-loss risk between appointments rather than every few months
  • Peer-reviewed estimates: 15 to 40% of weight lost on GLP-1 medication is lean mass rather than fat, roughly a quarter in meta-analyses [1-3]
  • Around 70% of patients stopped GLP-1 treatment within a year in real-world analyses [6]; most regain the weight, and it returns with a worse fat-to-muscle ratio [4,5]
  • A randomised controlled trial, measured by DXA body scanning, is in design with the University of Cambridge to test the score against gold-standard body-composition measurement
  • First patient cohorts onboarding now. Founder, members and clinicians available for interview

Weight-loss injections are now part of mainstream healthcare in the UK. The question gaining urgency in the medical literature is not the number on the scale, but what the weight that disappears is made of. Peer-reviewed estimates suggest between 15 and 40% of the weight lost on GLP-1 medication is lean mass rather than fat, roughly a quarter in meta-analyses [1-3]. And when treatment stops, as it did within a year for around 70% of patients in real-world analyses [6], the weight tends to return fatter than it left: in one year-long study, every kilogram of fat lost took 0.26kg of lean tissue with it, while every kilogram of fat regained brought back just 0.12kg [4,5]. Drug companies are now racing to develop compounds that preserve muscle during treatment. Almost nobody, however, is measuring the problem in the patients taking the drugs today.

From this week, one UK service is. Heracles Health, the clinician-led longevity and weight-loss platform, has become the first UK provider whose clinicians can see a live muscle-safety score for every patient, updated daily between appointments. The scoring system, LeanShield, is built by ParrotPal Group and already runs inside consumer apps used by more than one million people.

The gap it closes is structural. A typical weight-loss patient sees their prescriber a handful of times a year, while their body changes every week. A Heracles clinician opening the dashboard on a Monday morning can now see who held their protein target over the weekend, whose score has been sliding for a fortnight, and who needs a phone call rather than a routine review in three months.

"Five in six people in the UK don't have a gym membership [7], yet almost every weight-loss plan still starts with 'go to the gym'. That plan is written for an imaginary patient. We built ours for the real one: ten minutes at home, no kit, no cost. Three sets of squats while the kettle boils, wall presses, chair sit-to-stands. Each one flows straight into their score, so they see the payoff in real time. The muscle you lose doesn't wait for your next appointment. Now the care doesn't either."

Scott Flear, founder and chief executive, ParrotPal Group

Both companies are precise about the science: the medication itself does not strip muscle. Muscle loss follows any large, rapid calorie deficit where protein is low and resistance training is missing, whether the deficit comes from an injection, a crash diet or surgery. What GLP-1s change is the feedback. The drugs quieten appetite so effectively that a patient can sit in a severe deficit for months without noticing it. "They feel fine until things are not fine," said Flear. "That is exactly why the answer is measurement and small daily actions. Protein, stimulus, feedback. The drug removes the hunger. Someone still has to mind the muscle."

The company calls its approach "micro-stimulus". Rather than prescribing hour-long sessions, the platform nudges small, immediate actions and shows the predicted payoff before the effort: what a specific ten-minute session, using equipment the patient actually owns, will do to tomorrow's score. The logic rests on five decades of resistance-training research showing that the stimulus needed to maintain muscle is far smaller than the training volumes needed to build it.

The starting point is sobering. Across ParrotPal's member base, the average first LeanShield score is 49, a level the company's data associates with the zone where 30 to 40% of weight loss comes from lean mass. Members enrolled in LeanShield improve their scores by an average of 50% within the first 30 days, according to company data.

The launch also lands squarely on the direction of national policy. The government's 10 Year Health Plan for England commits to expanding access to weight-loss medication on a "pay for impact on health outcomes" basis, and to using "continuous monitoring to help make proactive management of patients the new normal". Outcome-based payment needs an outcome you can measure, and proactive management needs a signal worth acting on. LeanShield gives weight-loss care exactly that: a continuously measured outcome between appointments.

For clinics, the service is wrap-around and automated for the patient. ParrotPal handles the daily details: the logging, the nudges, the micro-workouts, the motivation. Clinicians get the data and the improvement, knowing their patients are looked after between visits. One NHS obesity specialist who reviewed the system called it "a total game changer", describing patients who lose a lot of weight and a lot of strength while standard lifestyle recommendations fail to produce any action.

The change shows up in small, human moments. One member in the testing community had decided to skip her weights one morning while looking after her grandson. "When I saw my score fall by 3, I clicked 'get workout', it gave me a home version, and it got me moving there and then. This is a game changer." Another logged a 30-minute dumbbell workout and watched her score climb from 57 to 70 the same evening.

"GLP-1 medications may prove to be one of the most significant therapeutic advances of our era. But rapid weight loss has a cost that too few are talking about.

"When the weight comes off quickly, patients often feel too fatigued to train and less than motivated to get enough protein. The result can be losing muscle alongside fat, which can lead to a more fragile body.

"Too many platforms are racing to prescribe without owning the consequences.

"That's why we're partnering with ParrotPal. Their LeanShield programme is designed to help our members protect lean mass and stay adherent to what actually matters: preserving muscle, strength, and function."

Tom Pascoe, CEO, Heracles Health

LeanShield is patent pending and was developed with the guidance of Professor Nick Wareham, Director of the Cambridge Institute of Metabolic Science. A randomised controlled trial, measured by DXA body scanning, is in design with the University of Cambridge to test the score against gold-standard body-composition measurement. The company is explicit that the trial could go against it: in its words, if you are going to call something a safety score, you fund the science that checks it.

References

  1. Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine 2021;384:989-1002. In the trial's DXA body-composition substudy, lean mass accounted for approximately 39% of total weight lost.
  2. Prado CM, Phillips SM, Gonzalez MC, Heymsfield SB. Muscle matters: the effects of medically induced weight loss on skeletal muscle. The Lancet Diabetes & Endocrinology 2024;12:785-787. Lean mass reported at 25 to 39% of weight lost with GLP-1-based therapy.
  3. Karakasis P, et al. Effect of glucagon-like peptide-1 receptor agonists and co-agonists on body composition: systematic review and network meta-analysis. Metabolism: Clinical and Experimental 2025;164:156113. 22 randomised trials, 2,258 participants; lean mass accounted for approximately 25% of total weight lost.
  4. Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism 2022;24:1553-1564. Around two-thirds of lost weight was regained within a year of stopping.
  5. Beavers KM, et al. Is lost lean mass from intentional weight loss recovered during weight regain in postmenopausal women? American Journal of Clinical Nutrition 2011;94:767-774. For every 1kg of fat lost during the weight-loss intervention, 0.26kg of lean tissue was lost; for every 1kg of fat regained over the following year, only 0.12kg of lean tissue was regained.
  6. Prime Therapeutics real-world claims analyses (2023): 71% of commercially insured members who initiated GLP-1 therapy for weight loss in 2021 were no longer on therapy at one year. Persistence has improved in more recent cohorts: Marshall LZ, et al. Trends in 1-year persistence and adherence among initiators of high-potency, weight loss-indicated GLP-1 receptor agonists. Journal of Managed Care & Specialty Pharmacy 2026;32(3):281. Persistence rose from 33% (2021 initiators) to 61% (first half of 2024).
  7. Leisure DB, State of the UK Fitness Industry Report 2025: 11.3 million UK gym members, a penetration rate of 16.6% of the population, both all-time highs. The "five in six" figure is the inverse, rounded.

Notes to editors

About ParrotPal Group

ParrotPal Group builds the first platform designed around a real-time muscle-protection score. Its products include the ParrotPal app (700,000+ users, 4.7 stars on the App Store), the women's health brand Turtle Method, and LeanShield, the muscle-safety intelligence layer licensed to clinics and partners. parrotpal.com

About Heracles Health

[Heracles boilerplate, to be supplied and approved by Heracles.]

Press contact: partnerships@parrotpal.com

← Back to ParrotPal