Press release · For immediate release

Weight-loss drugs take muscle with the fat. A UK clinic just put a daily muscle-protection score in patients' hands.

London, 15 June 2026. Heracles launches a UK-first pilot putting a daily muscle-protection score in front of patients and clinicians, powered by LeanShield from ParrotPal Group.

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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, the clinician-led longevity and weight-loss platform, has become the first UK provider to pilot a daily muscle-protection score that patients and their care team can see between appointments, as an investigational metric reviewed alongside standard care. 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 see who held their protein target over the weekend and whose score has been sliding, and offer encouragement and support between scheduled reviews.

"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 care needs a signal worth studying. LeanShield is built to provide exactly that kind of signal: a continuously measured muscle-protection outcome between appointments, which this pilot is designed to evaluate.

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 see the data and the engagement, knowing their patients have support between visits. One NHS obesity specialist who reviewed the approach described the gap it addresses: patients who lose a lot of weight and a lot of strength while standard lifestyle advice too often fails to translate into 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

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

• Regulatory status: LeanShield is a wellness and evidence-generation tool, not a medical device, and the LeanShield score is not a diagnostic test. The Heracles collaboration is an investigational pilot: the score is used as an investigational metric to gather real-world evidence on muscle preservation during weight-loss treatment, alongside and not in place of standard clinical assessment. Clinical validation, including the DXA-referenced study in design with the University of Cambridge, is ongoing. Participating clinicians and patients acknowledge this status.
• On the "UK first" claim: this refers to a clinical pilot offering weight-loss patients a daily muscle-protection score as an investigational metric. The companies are not aware of any other UK service offering this. We welcome corrections.
• Sources: full references for the lean-mass, discontinuation and regain figures are listed above. Further reading available on request.
• Policy context: the 10 Year Health Plan for England (gov.uk) commits to weight-loss medication partnerships paid "for impact on health outcomes", continuous monitoring as "the new normal", and care that is "digitally by default, in a patient's home if possible". This launch is a working example of all three shifts: hospital to community, analogue to digital, sickness to prevention.
• Interviews: Scott Flear (founder, ParrotPal Group), ParrotPal members willing to share their stories, and Tom Pascoe (CEO, Heracles) are available. Contact: jacqui+press@parrotpal.com.
• Company data caveat: the score-improvement figures are ParrotPal's own member data, not trial results. The Cambridge RCT is in design.
• Assets: logos, product imagery and founder photography available on request from jacqui+press@parrotpal.com.

About ParrotPal Group

ParrotPal Group builds the first platform designed around a real-time muscle-protection score. Its consumer apps, ParrotPal and the women's health brand Turtle Method, reach more than one million users across its brands and are rated 4.7 stars on the App Store. LeanShield is the muscle-protection intelligence layer offered to clinics and partners as an investigational metric; it is not a medical device. parrotpal.com

Recognition

ParrotPal Group's work has been recognised across UK technology and health:

Innovate UK: Winner, AI for Healthcare Resilience and Winner, Women in AI  |  Tech Nation NextWave: Winner  |  FemTech World Awards 2026: Top 3, AI for Health (Turtle Method)  |  UK Business Tech Awards 2026: Finalist, Healthtech Company of the Year  |  SXSW London and KPMG: Top 20

About Heracles

Heracles is the UK’s first longevity platform built for men. Its mission is simple but bold: to help men live longer, stronger, and better, by combining world-class medical care with tools for everyday performance. No shame. No shortcuts. Just science, structure, and support that actually works. Heracles doesn’t dwell on problems; it focuses on progress. heracles.co

Press contact: jacqui+press@parrotpal.com

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