Saxenda (liraglutide 3.0 mg) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for weight management in adults with obesity. For individuals with class III obesity (BMI ≥40 kg/m² or ≥35 kg/m² with comorbidities), Saxenda represents one component of comprehensive treatment alongside dietary modification, physical activity, and behavioural support. NICE recommends Saxenda for adults with BMI ≥35 kg/m² and weight-related comorbidities, prescribed within specialist weight management services. Clinical trials demonstrate average weight loss of 8% at 56 weeks, with improvements in cardiometabolic risk factors. Treatment requires careful patient selection, monitoring, and integration within multidisciplinary care pathways.

Understanding Saxenda and Obesity

Saxenda (liraglutide 3.0 mg) is a once-daily subcutaneous injection licensed in the UK for weight management in adults with obesity or overweight with weight-related comorbidities. It is also licensed for weight management in adolescents (12 to <18 years) with body weight above 60 kg and obesity (BMI corresponding to ≥30 kg/m² in adults).

Class III obesity, clinically defined as a body mass index (BMI) of 40 kg/m² or above (or 35 kg/m² with significant comorbidities), represents a serious health condition associated with increased risk of type 2 diabetes, cardiovascular disease, obstructive sleep apnoea, and certain cancers. The term "morbid obesity" has historically been used to reflect the substantial impact on health and quality of life, though person-first language is now preferred.

Saxenda belongs to the glucagon-like peptide-1 (GLP-1) receptor agonist class of medications. It works by mimicking the action of the naturally occurring hormone GLP-1, which is released from the intestine after eating. The mechanism of action involves several pathways: it slows gastric emptying, which prolongs the feeling of fullness after meals; it acts on appetite centres in the hypothalamus to reduce hunger and food cravings; and it may influence food intake regulation. Unlike its lower-dose formulation (Victoza) used for type 2 diabetes, Saxenda is specifically formulated and licensed for chronic weight management.

For individuals with class III obesity, pharmacological interventions like Saxenda represent one component of a multifaceted treatment approach. Weight loss in this population is clinically important because even modest reductions (5-10% of body weight) can significantly improve metabolic parameters, reduce cardiovascular risk factors, and enhance mobility and psychological wellbeing. However, it is essential to understand that Saxenda is not a standalone solution and must be combined with dietary modification, increased physical activity, and behavioural support to achieve sustainable outcomes.

Clinical Efficacy of Saxenda in Severely Obese Patients

The clinical evidence for Saxenda's efficacy comes primarily from the SCALE (Satiety and Clinical Adiposity – Liraglutide Evidence) programme, a series of randomised controlled trials involving over 5,000 participants. In the pivotal SCALE Obesity and Prediabetes trial, participants receiving liraglutide 3.0 mg achieved an average weight loss of 8.0% of initial body weight at 56 weeks, compared to 2.6% in the placebo group. Importantly, 63.2% of liraglutide-treated patients achieved at least 5% weight loss, and 33.1% achieved at least 10% weight loss, compared to 27.1% and 10.6% respectively in the placebo group.

Whilst these landmark trials included participants with BMI ≥30 kg/m² (or ≥27 kg/m² with comorbidities), individual responses vary considerably. The absolute weight loss in kilograms may be greater in heavier individuals, even if the percentage reduction is similar. For example, a 7% weight loss represents 14 kg for someone weighing 200 kg, compared to 7 kg for someone weighing 100 kg.

Beyond weight reduction, Saxenda has shown effects on cardiometabolic risk factors. Clinical trials have shown improvements in glycaemic control (including reduced progression to type 2 diabetes in those with prediabetes), blood pressure, and lipid profiles. Quality of life measures, including physical functioning and self-esteem, also showed improvements in clinical studies. Weight loss typically stabilises after several months of treatment, and maintaining adherence to lifestyle modifications is crucial for sustaining benefits. Patients should be counselled that Saxenda facilitates weight loss but does not guarantee it, and individual responses vary considerably. Weight regain commonly occurs after discontinuation of treatment.

Prescribing Criteria and Eligibility for Saxenda

In the UK, Saxenda is licensed for use in adults with a BMI of 30 kg/m² or greater, or 27 kg/m² or greater in the presence of at least one weight-related comorbidity such as type 2 diabetes, hypertension, dyslipidaemia, or obstructive sleep apnoea. This means individuals with class III obesity (BMI ≥40 kg/m²) clearly meet the licensing criteria.

NICE technology appraisal guidance (TA664) recommends Saxenda as an option for managing weight in adults with a BMI of at least 35 kg/m² and a weight-related comorbidity (or a BMI of at least 32.5 kg/m² for people from South Asian, Chinese, Black African or Caribbean backgrounds). According to NICE, Saxenda should only be prescribed within a specialist weight management service with multidisciplinary input, and only if the person has not responded to previous tier 2 interventions.

Before prescribing Saxenda, clinicians must conduct a comprehensive assessment including: detailed weight history and previous weight management attempts; evaluation of eating patterns and physical activity levels; screening for eating disorders or psychological contraindications; assessment of comorbidities and cardiovascular risk; review of current medications that may affect weight; and measurement of baseline parameters (weight, BMI, waist circumference, blood pressure, HbA1c or fasting glucose, lipid profile, and liver function tests).

Saxenda should only be initiated as part of a comprehensive weight management programme that includes dietary intervention, increased physical activity, and behavioural support. Saxenda is not recommended during pregnancy, and women should discontinue treatment if pregnancy occurs. Patients should be informed that treatment is intended for long-term use, as weight regain commonly occurs after discontinuation.

Treatment response should be formally assessed after 12 weeks at the maintenance dose (3.0 mg daily). Treatment should be discontinued if patients have not achieved at least 5% weight loss at this point, as continued use is unlikely to produce clinically meaningful benefits. For those who respond well to Saxenda, NHS funding is typically available for up to 2 years of treatment, with regular monitoring of efficacy, tolerability, and cardiovascular risk factors. Prescribers should also consider whether patients might be candidates for bariatric surgery, which remains the most effective intervention for class III obesity and may be more cost-effective in the long term.

Safety Considerations and Precautions

The most common adverse effects of Saxenda are gastrointestinal, occurring in the majority of patients, particularly during dose escalation. These include nausea (experienced by approximately 40% of users), diarrhoea, constipation, vomiting, dyspepsia, and abdominal pain. These symptoms are usually mild to moderate, transient, and can be minimised by gradual dose titration over five weeks (starting at 0.6 mg daily and increasing by 0.6 mg weekly to the target dose of 3.0 mg). Patients should be advised to eat smaller, more frequent meals and avoid high-fat foods, which may exacerbate nausea.

More serious but less common adverse effects require careful monitoring. Acute pancreatitis has been reported with GLP-1 receptor agonists, though causality remains uncertain. Patients should be counselled to seek immediate medical attention if they experience severe, persistent abdominal pain radiating to the back, particularly if accompanied by vomiting. Saxenda should be discontinued if pancreatitis is suspected and not restarted if confirmed. There is also a theoretical risk of thyroid C-cell tumours based on rodent studies, though no causal relationship has been established in humans. Patients with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2) should be counselled about this potential risk, and patients should report any neck masses or persistent hoarseness.

Other important safety considerations include: hypoglycaemia risk in patients taking concomitant insulin or sulphonylureas (dose reduction of these medications may be necessary); gallbladder disease (cholelithiasis and cholecystitis have been reported, likely related to rapid weight loss); increased heart rate (typically 2-3 beats per minute increase); and potential effects on renal function, particularly in patients with pre-existing renal impairment who develop dehydration from gastrointestinal side effects. Caution is advised in severe renal impairment or end-stage renal disease due to limited experience in these populations.

Patients should be advised to contact their healthcare provider if they experience: persistent severe abdominal pain; signs of gallbladder problems (right upper quadrant pain, particularly after eating); symptoms of depression or suicidal ideation; signs of dehydration; hypersensitivity reactions; or any unexplained neck lump or hoarseness. Regular monitoring should include weight, blood pressure, heart rate, and periodic assessment of renal function and glycaemic parameters in those with diabetes or prediabetes.

Patients should be advised to report any suspected side effects to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Saxenda as Part of Comprehensive Weight Management

For individuals with class III obesity, Saxenda should never be viewed as a standalone treatment but rather as one component of a comprehensive, multidisciplinary weight management programme. The most effective approach combines pharmacotherapy with intensive lifestyle intervention, including structured dietary modification, progressive physical activity, and cognitive-behavioural therapy to address eating behaviours and psychological factors contributing to obesity.

Dietary intervention should focus on creating a sustainable calorie deficit whilst ensuring nutritional adequacy. For patients with severe obesity, this typically involves reducing energy intake by 500-1000 kcal per day, emphasising whole foods, lean proteins, vegetables, and whole grains whilst limiting ultra-processed foods, added sugars, and saturated fats. Referral to a registered dietitian is highly beneficial for personalised meal planning and ongoing support. Physical activity should be gradually increased according to individual capability, starting with low-impact activities such as walking or swimming, with a long-term goal of 150-300 minutes of moderate-intensity activity per week as recommended by the UK Chief Medical Officers' Physical Activity Guidelines.

Behavioural support is crucial for addressing the psychological and environmental factors that influence eating patterns. This may include: self-monitoring of food intake and physical activity; identifying and managing triggers for overeating; developing coping strategies for emotional eating; setting realistic, achievable goals; and building a supportive social environment. Group-based programmes or individual counselling with a psychologist or behavioural therapist can significantly enhance outcomes.

For patients with class III obesity, bariatric surgery remains the most effective long-term intervention and should be discussed as an option for those who meet NICE criteria (BMI ≥40 kg/m² or ≥35 kg/m² with comorbidities). Saxenda may be considered within specialist services for those who decline surgery or are not suitable candidates. Use of Saxenda before or after bariatric surgery should be specialist-led and evidence in these contexts is still emerging. Regular follow-up with the multidisciplinary team is essential to monitor progress, adjust treatment as needed, address barriers to adherence, and provide ongoing motivation and support for sustainable lifestyle change.

Referral to NHS specialist weight management services (Tier 3 or 4) should be considered for people with class III obesity, in line with NICE guidance on obesity management.

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