Eamonn Brady MPSI discusses the causes, consequences, and treatment options for obesity
Part 1: The Condition
Epidemiology
Obesity is a chronic, relapsing disease and remains one of the most pressing health challenges in Ireland and other Western countries. From the pharmacy counter to hospital clinics, the consequences are seen daily: More prescriptions for antihypertensives and lipid-lowering agents, increased demand for sleep apnoea assessment, and younger patients presenting with type 2 diabetes, fertility problems and metabolic dysfunction-associated steatotic liver disease (MASLD), previously referred to as non-alcoholic fatty liver disease.
Obesity is not simply the result of individual choices. It is shaped by genetics, appetite regulation, physiology, the built environment, food marketing, socioeconomic pressures, sleep, stress, and medicines that promote weight gain. Recognising obesity as a disease helps frame the pharmacist’s role in a practical way: Supporting patients with evidence-based advice, structured weight management, medicines optimisation, and signposting to appropriate HSE or specialist services.
Irish data continue to show that excess weight is common. The 2025 Irish Health Survey reported that 21.5 per cent of adults were living with obesity, with the highest rates seen in those aged 55-to-64 years. Healthy Ireland and HSE data also show that a majority of Irish adults are either overweight or living with obesity, while childhood rates remain a concern, particularly in areas of socioeconomic disadvantage. The latest COSI data for Ireland reported that 17.7 per cent of primary school children were living with overweight or obesity in 2022-2023, while 73 per cent had a healthy weight.
Beyond cardiometabolic disease, obesity increases the risk of several cancers, including breast, colorectal and endometrial cancer. It is also associated with musculoskeletal disease, depression, infertility, pregnancy complications, and reduced quality of life. For pharmacy practice, this often means more complex polypharmacy, adherence challenges, and the need to avoid, where possible, iatrogenic weight gain from medicines such as some antidepressants, antipsychotics, corticosteroids, insulin, and sulfonylureas.
Pathophysiology
Body weight is regulated by a complex neuro-hormonal system linking the gut, adipose tissue, pancreas, and brain. Key signals include leptin, ghrelin, insulin, GLP-1, GIP, peptide YY and cholecystokinin. These signals influence appetite, satiety, reward pathways, gastric emptying, glucose regulation, and energy expenditure.
In obesity, the normal regulation of appetite and satiety is disrupted. Leptin resistance may develop, meaning that higher body fat stores do not reliably translate into reduced appetite. Reward circuitry, stress pathways and the hypothalamic-pituitary-adrenal axis can also reinforce cravings and energy-dense food choices. After weight loss, resting energy expenditure may fall, a process known as adaptive thermogenesis, which partly explains why weight regain is common without ongoing support.
This biology is important for pharmacists to understand. Many patients have repeatedly tried to lose weight and feel they have ‘failed’. Explaining obesity as a chronic disease with biological drivers can reduce stigma and improve engagement with lifestyle measures, pharmacotherapy, and long-term follow-up.
How Are ‘Overweight’ and ‘Obesity’ Classified?
BMI remains the most widely used measure for classifying weight status in adults. BMI is calculated as weight in kilograms divided by height in metres squared.
BMI categories:
? Underweight: <18.5kg/m²
? Healthy weight: 18.5-24.9kg/m²
? Overweight: 25.0-29.9kg/m²
? Obesity class I: 30.0-34.9kg/m²
? Obesity class II: 35.0-39.9kg/m²
? Obesity class III: ?40.0kg/m²
NICE also recommends considering waist-to-height ratio alongside BMI, particularly in adults with a BMI below 35kg/m². A waist measurement less than half a person’s height indicates lower cardiometabolic risk.
NICE also recommends considering waist-to-height ratio alongside BMI, particularly in adults with a BMI below 35kg/m²
Weight and Obesity Rates and Trends in Ireland
Recent Irish data confirm that excess weight remains common. The 2025 Irish Health Survey reported that 21.5 per cent of adults were living with obesity. The latest COSI report found that 17.7 per cent of primary school children were living with overweight or obesity in 2022-2023.
Risk Factors
? Genetic and epigenetic influences.
? Early-life exposures.
? Environmental and behavioural factors.
? Socioeconomic factors.
? Medical causes including hypothyroidism, PCOS and Cushing’s syndrome.
? Medicines associated with weight gain including corticosteroids, some antipsychotics, tricyclic antidepressants, mirtazapine, sodium valproate, insulin, sulfonylureas, and some beta-blockers.
Health Consequences
Obesity increases all-cause mortality and contributes to metabolic, cardiovascular, respiratory, gastrointestinal, hepatic, musculoskeletal, reproductive, oncological and mental health disorders. MASLD and MASH are the updated terms replacing NAFLD and NASH. Even sustained weight loss of 5-to-10 per cent improves blood pressure, glycaemic control, triglycerides, and liver health.
Non-Pharmacological Approaches
Lifestyle intervention remains the foundation of obesity management and should accompany all pharmacological and surgical treatments. Sustainable changes in eating habits, physical activity, sleep, and behavioural support consistently produce better long-term outcomes than isolated interventions.
Dietary Strategies
? Encourage minimally processed foods, vegetables, fruit, pulses, wholegrains, lean protein, and healthy fats.
? Ensure adequate protein intake to help preserve lean muscle during weight loss, particularly in older adults and patients receiving GLP-1 medicines.
? Create an individualised calorie deficit using an eating pattern the patient can maintain long-term. Mediterranean-style diets have the strongest evidence for overall cardiometabolic health, while lower-carbohydrate or DASH-style diets may suit selected patients.
? Limit ultra-processed foods, sugar-sweetened drinks, and excess alcohol.
? Practical advice such as meal planning, shopping with a list, batch cooking, portion awareness and keeping healthy snacks visible often has greater long-term impact than restrictive dieting.
Physical Activity
Current guidance recommends at least 150 minutes of moderate-intensity activity each week together with muscle-strengthening exercise on at least two days weekly. Resistance exercise is particularly important during weight loss to preserve lean muscle mass. Encourage patients to choose enjoyable activities such as brisk walking, cycling, swimming, or gardening, and reassure those with obesity that several short bouts of activity throughout the day provide meaningful health benefits.
Behavioural Techniques
Self-monitoring using food diaries or smartphone apps, SMART goals, identifying triggers for overeating and developing coping strategies all improve long-term success. Good sleep (seven-to-nine hours), stress management and social support should form part of every weight-management plan. Pharmacists should also signpost suitable patients to HSE Healthy Weight services, Slí na Sláinte walking routes and community dietetic services where available.
Weight-Loss Apps: A Pharmacist’s Perspective
Digital health tools can improve adherence when used alongside lifestyle advice, rather than replacing it. Popular apps available in Ireland include MyFitnessPal, Cronometer, Lose It!, Noom, BetterMe, WalkFit, Lifesum, FatSecret and MyNetDiary. Features vary from calorie and nutrient tracking, to behavioural coaching and structured exercise programmes. Prices change regularly; therefore, pharmacists should encourage patients to compare current subscription costs before purchasing paid versions.
For most patients, the free versions provide sufficient functionality. Patients needing detailed nutritional analysis may benefit from Cronometer, those wanting behavioural coaching may prefer Noom, while MyFitnessPal and Lose It! remain good all-round options because of their extensive food databases.
Pharmacist Take-Home Points
? Apps should support, not replace, evidence-based lifestyle interventions.
? Match the app to the patient’s goals, confidence with technology and budget.
? Encourage realistic expectations and long-term habit formation rather than rapid weight loss.
? Patients receiving GLP-1 medicines should prioritise adequate protein intake and resistance exercise to minimise loss of lean muscle.
? When lifestyle measures alone are insufficient and appropriate BMI criteria are met, anti-obesity medicines should be viewed as an adjunct to comprehensive lifestyle management rather than a substitute for it.
Part 2: Pharmacological Treatment Options
Drug treatment should always be used alongside lifestyle intervention rather than as a replacement. In Ireland, anti-obesity medicines can be broadly divided into non-incretin therapies and incretin-based therapies (GLP-1 receptor agonists and dual GIP/GLP-1 receptor agonists). The latter now dominate clinical practice because they produce substantially greater and more sustained weight loss.
Drug treatment should always be used alongside lifestyle intervention rather than as a replacement
Type 1: Non-Incretin Pharmacological Options, ie, Medicines Other Than GLP-1 Injections
Orlistat (Xenical) remains the only licensed oral anti-obesity medicine widely available in Ireland. It reduces intestinal fat absorption by approximately 30 per cent and is most effective when combined with a low-fat diet. Gastrointestinal adverse effects including steatorrhoea (fatty stools), flatulence, and faecal urgency remain the principal limitation. Patients should take a multivitamin containing fat-soluble vitamins at bedtime. Xenical is available on private prescription and is not routinely reimbursed under GMS or DPS for obesity.
Naltrexone/bupropion (Mysimba) acts centrally to reduce appetite and food cravings. Clinical trials demonstrate average weight loss of approximately 5-to-8 per cent when combined with lifestyle measures. Nausea, insomnia, and headache are common. It is contraindicated in seizure disorders, uncontrolled hypertension, chronic opioid use, and eating disorders. In Ireland, it remains available privately without routine HSE reimbursement.
Metformin is not licensed specifically for obesity but is sometimes used in patients with prediabetes, insulin resistance, or polycystic ovary syndrome where modest weight loss may be beneficial.
Topiramate is also unlicensed for obesity in Ireland and is generally reserved for specialist practice because of cognitive adverse effects and teratogenicity.
Type 2: GLP-1 Receptor Agonists and Dual GIP/GLP-1 Receptor Agonists
Incretin-based therapies have transformed obesity management. They reduce appetite, enhance satiety and slow gastric emptying, resulting in clinically meaningful and sustained weight loss when combined with lifestyle intervention.
Medicines currently relevant to Irish practice include semaglutide (Ozempic and Wegovy), liraglutide (Victoza and Saxenda), dulaglutide (Trulicity), exenatide (Byetta and Bydureon), oral semaglutide (Rybelsus) and tirzepatide (Mounjaro). Most are administered as once-weekly or once-daily subcutaneous injections, while Rybelsus is the only oral GLP-1 receptor agonist.
Licensing in Ireland
? Wegovy (semaglutide), Saxenda (liraglutide) and Mounjaro (tirzepatide) are licensed for chronic weight management in appropriate adults.
? Ozempic, Trulicity, Victoza, Byetta, Bydureon and Rybelsus are licensed for type 2 diabetes.
? Rybelsus remains licensed for diabetes only and should not be prescribed solely for weight management.
? Although Ozempic was widely prescribed off-label for obesity before dedicated weight-loss products became available, current prescribing should preferentially follow licensed indications.
Medicine shortages affecting GLP-1 medicines have eased considerably compared with 2023-2024, although intermittent supply issues may still occur. Pharmacists should continue to follow HPRA and manufacturer advice where shortages arise.
*Victoza, Byetta, Bydureon are now off the market in Ireland.
Pharmacist Practice Points
? Confirm the medicine is being prescribed for an appropriate licensed indication.
? Counsel patients regarding gradual dose escalation and expected gastrointestinal adverse effects.
? Reinforce adequate protein intake and resistance exercise to reduce lean muscle loss during rapid weight loss.
? Advise patients that pharmacotherapy is an adjunct to comprehensive lifestyle management and long-term follow-up.
GLP-1 Medicines: Key Products Used in Irish Practice
Semaglutide (Ozempic)
Ozempic is licensed for type 2 diabetes and not for obesity. It became widely known as the ‘skinny jab’ because of its weight-loss effects before dedicated obesity medicines became available. Common adverse effects include nausea, vomiting, diarrhoea, and constipation, which can usually be minimised by gradual dose escalation. Patients with diabetes may receive Ozempic through the Long-Term Illness Scheme when prescribed for its licensed indication.
Off-Label Use for Obesity
Prescribing medicines outside their licence is legally permitted in appropriate circumstances but should be clinically justified. Since Wegovy and Mounjaro are now licensed specifically for chronic weight management, these products should generally be preferred where anti-obesity pharmacotherapy is indicated. Pharmacists should ensure patients understand the indication for which their medicine has been prescribed.
Semaglutide (Wegovy)
Wegovy is licensed for chronic weight management and is administered once weekly by subcutaneous injection. Treatment begins at 0.25mg weekly and is increased every four weeks to a maintenance dose of 2.4mg weekly as tolerated.
The STEP clinical programme demonstrated mean weight loss approaching 15 per cent at 68 weeks, while the SELECT cardiovascular outcomes trial showed a significant reduction in major adverse cardiovascular events in adults with overweight or obesity and established cardiovascular disease, even without diabetes.
In Ireland, Wegovy remains available primarily on private prescription and reimbursement remains limited.
Liraglutide (Saxenda)
Saxenda is administered once daily and remains an effective option, although weekly agents are generally preferred because of greater efficacy and convenience. The SCALE programme demonstrated average weight loss of approximately 8 per cent after 56 weeks. Eligible patients may access treatment through the HSE Managed Access Protocol where current criteria are met; otherwise, treatment is generally private.
Tirzepatide (Mounjaro)
Mounjaro is the first dual GIP/GLP-1 receptor agonist licensed for chronic weight management. Treatment starts at 2.5mg once weekly and is titrated every four weeks to a maximum maintenance dose of 15mg weekly.
The SURMOUNT-1 trial demonstrated mean weight reductions of approximately 15 per cent, 19.5 per cent and 20.9 per cent with the 5mg, 10mg, and 15mg doses respectively over 72 weeks, representing the greatest weight loss reported with currently licensed pharmacotherapy.
Although availability has improved substantially since its launch, pharmacists should remain alert to occasional supply constraints and counsel patients not to interrupt treatment without consulting their prescriber.
General GLP-1 Counselling
Patients should eat slowly, stop eating when comfortably full, and prioritise adequate protein intake to help preserve lean muscle mass during weight loss. Resistance exercise should be encouraged alongside treatment. Nausea usually improves with gradual dose escalation, smaller meals, and avoidance of high-fat meals.
Counsel patients regarding the symptoms of gallstones and pancreatitis, ensure they remain well hydrated, and review medicines whose absorption may be affected by delayed gastric emptying. Patients using insulin or sulfonylureas may require dose adjustment to reduce hypoglycaemia risk.
Will Anti-Obesity Medicines Become Available on State Schemes?
The National Centre for Pharmacoeconomics (NCPE) continues to evaluate the clinical and cost-effectiveness of anti-obesity medicines before reimbursement decisions are made. As obesity affects a large proportion of the population, funding decisions must balance clinical benefit with affordability for the Irish healthcare system.
Although access has expanded internationally, widespread reimbursement in Ireland remains limited. Patients should therefore be advised that eligibility criteria and reimbursement arrangements may change as additional health-economic evidence and national guidance become available.
Key Message for Pharmacists
GLP-1 receptor agonists and dual GIP/GLP-1 receptor agonists have transformed obesity treatment, but medicines alone are not sufficient. Long-term success depends on sustained dietary change, regular physical activity, behavioural support, and ongoing follow-up. Pharmacists remain central to counselling patients, improving adherence, identifying adverse effects, and ensuring medicines are used appropriately within their licensed indications.
General GLP-1 Counselling
Advise patients to eat slowly, stop when comfortably full, prioritise protein intake and undertake regular resistance exercise to minimise loss of lean muscle mass. Smaller meals and slower dose escalation can reduce gastrointestinal adverse effects. Counsel patients regarding symptoms of pancreatitis and gallstones, maintain adequate hydration and review medicines whose absorption may be altered by delayed gastric emptying. GLP-1-based therapies should generally be avoided in patients with a personal or family history of medullary thyroid carcinoma or MEN2.
Will Mounjaro and Wegovy Become Available on State Schemes?
The National Centre for Pharmacoeconomics (NCPE) assesses the clinical and cost-effectiveness of medicines before advising the HSE on reimbursement. As obesity medicines have the potential to benefit large numbers of patients, reimbursement decisions require careful assessment of both clinical value and affordability.
Reimbursement arrangements continue to evolve. Pharmacists should refer to the latest HSE, PCRS and NCPE guidance rather than relying on anticipated timelines, as eligibility criteria and funded indications may change.
Comparative Overview
The comparative tables should be retained but updated before publication to reflect the latest Irish reimbursement status, availability, and product licence information, particularly for Wegovy, Mounjaro, and Saxenda.
Pharmacists’ Role in Obesity Management
Community pharmacists remain central to obesity care by:
? Identifying patients who may benefit from intervention using BMI, waist measurements, and cardiovascular risk assessment.
? Reviewing medicines that may contribute to weight gain and discussing suitable alternatives with prescribers where appropriate.
? Counselling on dose titration, expected weight-loss trajectories, adverse effects, and adherence.
? Monitoring for gastrointestinal adverse effects, dehydration, gallstones, and hypoglycaemia when GLP-1 medicines are combined with insulin or sulfonylureas.
? Explaining current HSE reimbursement arrangements.
? Providing long-term encouragement, relapse prevention, and realistic expectations, recognising obesity as a chronic relapsing disease rather than a failure of willpower.
Part 3: Longer-Term Non-Pharmaceutical Impact of Widespread Anti-Obesity Medicines
The increasing use of GLP-1 receptor agonists and dual GIP/GLP-1 receptor agonists such as semaglutide, liraglutide and tirzepatide has the potential to influence far more than individual patient health. If these medicines become more affordable and accessible over the coming decade, they could reshape healthcare demand, consumer behaviour, and several sectors of the wider economy. While many of these changes remain speculative, early evidence suggests that obesity pharmacotherapy may have effects well beyond clinical practice.
Healthcare
Effective obesity treatment could reduce the long-term burden of type 2 diabetes, cardiovascular disease, obstructive sleep apnoea, osteoarthritis, and metabolic liver disease. Although expenditure on medicines may increase initially, reductions in obesity-related complications could offset some healthcare costs over time.
Food and Beverage Industry
Food manufacturers are already adapting to changing consumer preferences. Increased demand for protein-rich foods, smaller portion sizes and healthier convenience meals has been reported, while some companies are reassessing product ranges in response to reduced appetite and changing purchasing habits among GLP-1 users.
Fitness and Lifestyle
Weight loss often improves mobility, allowing greater participation in physical activity. Demand for resistance training, exercise programmes and body composition monitoring may increase as greater emphasis is placed on preserving muscle mass during treatment.
Employment and Productivity
Improved physical health may reduce sickness absence and improve workplace productivity. Any economic benefit is likely to emerge gradually as reductions in obesity-related complications become apparent.
Social Considerations
Although wider access to effective obesity treatment may reduce some of the stigma associated with obesity, it also raises important ethical issues relating to equitable access, affordability, and unrealistic public expectations.
Medicines should be viewed as one component of comprehensive obesity management rather than a cosmetic intervention.
Overall
For pharmacists, these developments reinforce the importance of providing balanced, evidence-based advice. Anti-obesity medicines are likely to remain an increasingly important part of practice, but long-term success will continue to depend on sustainable lifestyle change, ongoing behavioural support, and appropriate clinical follow-up.
References on request
Written by Eamonn Brady (MPSI). Whelehans Pharmacies, 38 Pearse St and Clonmore, Mullingar. Tel 04493 34591 (Pearse St) or 04493 10266 (Clonmore). www.whelehans.ie
