GLP-1 medications are becoming a hot topic of conversation on social media platforms, gym floors, and in exercise studio conversations alike. With many proclaiming them to be the new miracle cure for weight loss.
For those living with obesity and need to lose weight for health reasons, these medications may offer the ‘kick start’ weight loss needed to motivate and potentially inspire other positive lifestyle changes. These include physical activity and healthier eating, which are essential for longer-term success and improved health and wellbeing.
However, there are risks associated with the use of GLP-1 medications, which include, but are not limited to:
- Unwanted side effects
- Non-prescribed availability
- Misuse via the shadow or black market
This article explores the current criteria for prescription of GLP-1 medications and looks at some of the benefits and risks associated with these medications.
Criteria for prescription
GLP-1 (glucagon-like peptide 1) receptor agonists are a group of medications that are being made available on NHS prescription to support weight loss in individuals who are living with obesity.
There are different types, which include:
- Glucagon-like peptide 1 (GLP-1) receptor agonists:
a. Semaglutide: Ozempic®, Wegovy®, Rybelsus®
b. Liraglutide: Victoza®. - Dual GLP 1/glucose-dependent insulinotropic polypeptide (GIP) receptor agonists:
a. Tirzepatide: Mounjaro®.
The criteria for prescription of GLP-1 medications include individuals with a body mass index (BMI) of 35 kg/m2 (32.5 for other ethnic groups) or above, and have at least one other weight-related comorbidity, including:
- pre-diabetes or type 2 diabetes
- high blood pressure
- dyslipidaemia
- cardiovascular disease
- obstructive sleep apnoea (NICE, 2025)
Benefits of use – positive health outcomes
Obesity, along with other criteria for GLP-1 prescription (type 2 diabetes, high blood pressure, and dyslipidaemia) form part of a cluster of conditions referred to as ‘metabolic syndrome’ (Metsyn). These conditions collectively increase the risk of heart attack and stroke. So, by supporting weight loss, GLP-1 medications have the potential to positively impact these other conditions and support improved health outcomes. According to the British Heart Foundation, these include:
- 22% lower risk of a cardiac arrest
- 11% lower risk of heart failure
- 9% lower risk of a heart attack
- 7% lower risk of ischaemic stroke.
- 24% less likely to have liver failure
- 22% less likely to have respiratory failure
- 12% less likely to develop Alzheimer’s disease.
- Lower risk of mental health issues, like substance use disorders, suicidal ideation, and schizophrenia.
In addition to significant weight loss, some users of GLP-1 medication report improvements to self-esteem and social confidence, as well as improvements in their eating habits and physical health.
Side effects – ‘all that glitters is not gold’
As the saying goes, ‘all that glitters is not gold’. There are several reports that many GLP-1 users (from 34% and up to 75% in some reports) stop taking the medications because of the side effects.
While the most reported side effects are mild Gastrointestinal (GI) disturbances, such as constipation, nausea, and vomiting (due to slower gastric emptying), other more serious GI side effects have been reported, along with hypoglycaemia and injection-site reactions. Although less frequently reported, other adverse effects may include cardiovascular events, gallstones, hepatic disorders, pancreatitis, acute renal failure, malignant neoplasms (cancerous tumours) and psychiatric disorders. (Fang et al., 2025; Ko et al., 2025; Filippatos, Panagiotopoulou and Elisaf, 2015)
Loss of muscle and bone
One significant consequence of using the GLP-1 medications is the loss of skeletal muscle mass (sarcopenia) and bone mass (osteopenia) associated with their use. It’s estimated that between 20% and 50% of the weight lost from using the GLP-1 medications can be attributed to loss of lean, fat-free mass, which is clearly not a desirable effect.
Those most at risk of muscle mass loss and bone mass loss are older adults (55+), which includes most post-menopausal women, and since obesity levels peak in the 55–74-year-old age group (Health Survey for England, 2024) it’s these populations for whom the GLP-1 medications are most likely being prescribed.
Risks associated with loss of muscle and bone mass
Loss of muscle and bone mass can lead to reduced physical function and muscle strength, fatigue, poor balance, and coordination, all of which increase the risk of falls, fractures, and frailty.
Loss of muscle mass also decreases resting metabolic rate, making weight loss maintenance more difficult when medication is stopped. Roberts (2026) reports that the regain of lost weight could be four times faster than when following other diet and exercise approaches. Another study reported that two-thirds of weight loss was regained within 1 year of stopping medication (Sforzo, et al., 2024). In addition to rapid weight gain, there is also a reversal on the beneficial effects of some cardiometabolic markers (West, S., et al. 2026).
To preserve muscle and bone mass, physical activity and healthy eating are essential.
The shadow market and misuse
What also needs to be considered is the ‘shadow’ market. This includes persons accessing GLP-1 medications (not-prescribed) via the internet, whether needed or not. This may include people with body dysmorphia and eating disorders or at risk of developing eating disorders, as well as athletes participating in weight-controlled, aesthetic and/or endurance sports or events.
There is currently limited research on the impact of GLP-1 medications in those with diagnosed eating disorders or those at risk of developing eating disorders. However, it’s known that eating disorder training or screening in many healthcare services and settings is limited, and eating disorders are often misdiagnosed or sometimes undiagnosed.
Since weight obsession, dieting, and thinness are drivers associated with many eating disorders, especially restrictive disorders like anorexia nervosa, this presents a significant risk, resulting potentially in some individuals misusing GLP-1 medications, which may worsen cognitive and behavioural symptoms linked with eating disorders (Dennis., 2024).
What do health and fitness professionals need to know?
With the use of GLP-1 medications increasing, it’s highly likely that exercise and fitness professionals will encounter clients who are using, or considering using, these medications, whether prescribed appropriately or obtained elsewhere.
The fitness industry, alongside healthcare services and professionals, plays an important role in supporting individuals to improve their health. However, to remain within their scope of practice, exercise and fitness professionals should focus on providing advice and guidance on physical activity, exercise, and healthier eating habits that support positive lifestyle behaviour change. These long-term changes are essential for maintaining weight loss and improving overall health outcomes.
If individuals request information about GLP-1 medications, fitness professionals should signpost them to appropriate healthcare professionals and to guidance provided by the NHS and NICE regarding eligibility and safe use.
The landscape surrounding GLP-1 medications is evolving rapidly, with new research and insights emerging on an ongoing basis. For this reason, it’s essential that exercise and fitness professionals stay informed and keep their knowledge up to date.
Our Level 4 Obesity and Diabetes course explores evidence-based interventions that support healthier lifestyles for individuals living with obesity or diabetes. It examines the role of lifestyle approaches such as physical activity, nutrition, and behaviour change, and considers how these interact with medical interventions within a broader healthcare context. The course provides exercise professionals with a deeper understanding of obesity and diabetes, helping them confidently support clients with complex metabolic health needs.
References
- British Heart Foundation (2025). Weight loss injections. [online] British Heart Foundation. Available at: https://www.bhf.org.uk/informationsupport/heart-matters-magazine/news/behind-the-headlines/weight-loss-injections.
- Dennis, K. (2024). GLP-1 Medications and Eating Disorders – National Eating Disorders Association. [online] National Eating Disorders Association. Available at: https://www.nationaleatingdisorders.org/glp-and-eating-disorders/.
- Guidance for the sport and physical activity sector on understanding the use of weight management medications. (2025). Available at: https://www.cimspa.co.uk/wp-content/uploads/2025/10/CIMSPA-uksport-Weight-Management-Medication-Guidance.pdf [Accessed 12 Jan. 2026].
- Fang, Y.E., Paik, J.M., Ortega-Montiel, J., Tesfaye, H., Wexler, D.J. and Patorno, E. (2025). Risk of Acute Pancreatitis and Biliary Events After Initiation of Incretin-Based Medications in Patients With Type 2 Diabetes. Diabetes care, [online] 48(12), pp.2127–2137. doi:https://doi.org/10.2337/dc25-1840.
- Filippatos, T.D., Panagiotopoulou, T.V. and Elisaf, M.S. (2015). Adverse Effects of GLP-1 Receptor Agonists. The Review of Diabetic Studies, [online] 11(3-4), pp.202–230. doi:https://doi.org/10.1900/rds.2014.11.202.
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- Ko, H.Y., Bea, S., Yoon, D., Hong, B., Bae, J.H., Cho, Y.M. and Shin, J.-Y. (2025). Incretin-based drugs and the risk of gallbladder or biliary tract diseases among patients with type 2 diabetes across categories of body mass index: a nationwide cohort study. The Lancet Regional Health – Western Pacific, [online] 56, p.101242. doi:https://doi.org/10.1016/j.lanwpc.2024.101242.
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