Does GLP-1 Help With Visceral Fat? UK Evidence and Guidance

Visceral fat—the deep abdominal fat surrounding vital organs—poses serious metabolic risks, including type 2 diabetes, cardiovascular disease, and non-alcoholic fatty liver disease. Does GLP-1 help with visceral fat? Emerging evidence suggests GLP-1 receptor agonists, a class of medications that mimic a natural gut hormone, may reduce visceral adipose tissue alongside overall body weight. These agents work by enhancing insulin secretion, suppressing appetite, and slowing gastric emptying. Whilst licensed in the UK for type 2 diabetes and weight management, their effects on visceral fat specifically remain an area of ongoing research. This article examines the mechanisms, available medications, expected outcomes, and safety considerations for GLP-1 therapy in visceral fat reduction.

What Is Visceral Fat and Why Does It Matter?

Visceral fat refers to adipose tissue stored deep within the abdominal cavity, surrounding vital organs including the liver, pancreas, and intestines. Unlike subcutaneous fat that sits just beneath the skin, visceral fat is metabolically active and produces inflammatory substances called adipokines. This type of fat cannot be pinched or easily seen, with accurate measurement requiring imaging techniques such as CT or MRI scans, though waist circumference provides a useful proxy measurement.

The accumulation of visceral fat poses significant health risks that extend far beyond cosmetic concerns. Excess visceral adiposity is strongly associated with:

• Type 2 diabetes mellitus and insulin resistance

• Cardiovascular disease and hypertension

• Non-alcoholic fatty liver disease (NAFLD)

• Certain cancers, including colorectal and breast cancer

• Metabolic syndrome

According to NHS guidance, waist circumference measurements exceeding 94 cm in men and 80 cm in women (for white European populations) indicate increased metabolic risk, largely driven by visceral fat accumulation. For individuals of South Asian, Chinese, and Japanese origin, these thresholds are lower at 90 cm for men and 80 cm for women, reflecting different body composition patterns and associated health risks.

Visceral fat produces hormones and inflammatory markers that interfere with normal metabolic processes, contributing to insulin resistance and systemic inflammation. UK clinical evidence demonstrates that reducing overall body weight—even modest reductions of 5–10%—can significantly improve metabolic health markers including HbA1c, blood pressure, and lipid profiles. This makes visceral fat reduction a key therapeutic target in managing obesity-related conditions, which is where newer pharmacological interventions such as GLP-1 receptor agonists have shown promise.

How GLP-1 Medications Work in the Body

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of medications that mimic the action of naturally occurring GLP-1, an incretin hormone produced by intestinal L-cells in response to food intake. These medications work through multiple complementary mechanisms that collectively promote weight loss and metabolic improvement.

The primary mechanisms of action include:

• Enhanced insulin secretion: GLP-1 receptor agonists stimulate glucose-dependent insulin release from pancreatic beta cells, improving glycaemic control without causing hypoglycaemia when glucose levels are normal

• Suppressed glucagon secretion: These agents inhibit inappropriate glucagon release from pancreatic alpha cells, reducing hepatic glucose production

• Delayed gastric emptying: By slowing the rate at which food leaves the stomach, GLP-1 medications prolong satiety and reduce postprandial glucose excursions

• Central appetite regulation: GLP-1 receptors in the hypothalamus and brainstem mediate reduced appetite and food intake, leading to decreased caloric consumption

Regarding visceral fat specifically, some imaging substudies suggest GLP-1 receptor agonists may reduce visceral adipose tissue alongside subcutaneous fat. These findings come from smaller imaging cohorts using computed tomography (CT) and magnetic resonance imaging (MRI), though it's important to note that preferential visceral fat reduction is not a licensed indication for these medications in the UK.

Some research also suggests these medications may have effects on ectopic fat deposition in the liver and pancreas, which could contribute to improved metabolic function. However, these effects are considered investigational and are not licensed indications in the UK. It's worth noting that when GLP-1 receptor agonists are used alongside insulin or sulfonylureas, there is an increased risk of hypoglycaemia, and dose adjustments of these medications may be required.

Which GLP-1 Medications Are Available in the UK?

Several GLP-1 receptor agonists are currently licensed and available through the NHS and private prescribers in the UK, approved by the Medicines and Healthcare products Regulatory Agency (MHRA) for specific indications. These medications differ in their formulation, dosing frequency, and licensed indications.

Currently available GLP-1 receptor agonists include:

• Semaglutide (Ozempic®, Wegovy®): Available as once-weekly subcutaneous injection. Ozempic is licensed for type 2 diabetes, whilst Wegovy is specifically licensed for weight management in adults with BMI ≥30 kg/m² or ≥27 kg/m² with weight-related comorbidities. Oral semaglutide (Rybelsus®) is also available for diabetes management.

• Dulaglutide (Trulicity®): Once-weekly subcutaneous injection licensed for type 2 diabetes management

• Liraglutide (Victoza®, Saxenda®): Daily subcutaneous injection. Victoza is indicated for diabetes, whilst Saxenda is licensed for weight management under similar criteria to Wegovy

• Exenatide (Byetta®, Bydureon®): Available as twice-daily or once-weekly formulations for type 2 diabetes

• Lixisenatide (Lyxumia®): Once-daily injection for type 2 diabetes

NICE guidance (NG28) recommends GLP-1 receptor agonists for type 2 diabetes management when certain glycaemic and weight criteria are met. For weight management specifically, NICE technology appraisals TA875 (semaglutide 2.4 mg/Wegovy) and TA664 (liraglutide 3 mg/Saxenda) support their use as part of specialist weight management services, alongside dietary modification and increased physical activity. Treatment is typically limited to a maximum of two years.

It is important to note that Ozempic is not licensed for weight management and should not be used off-label for this purpose, in line with NHS supply guidance. Access through the NHS may be limited due to commissioning decisions and ongoing supply constraints. Patients should be assessed by appropriately qualified healthcare professionals, with consideration of contraindications, potential drug interactions, and individual suitability. Private prescription is an alternative route, though costs can be substantial, and patients should discuss availability and costs with their prescriber or pharmacist.

Expected Results and Timeframes for Fat Loss

Clinical trial data and real-world evidence provide insight into the magnitude and timeline of weight loss achievable with GLP-1 receptor agonists. Results vary considerably between individuals based on baseline characteristics, adherence, lifestyle modifications, and the specific medication used.

Weight loss expectations:

In landmark trials such as STEP 1 (Semaglutide Treatment Effect in People with obesity) and SCALE (Satiety and Clinical Adiposity – Liraglutide Evidence), participants achieved average weight reductions of 14.9% of initial body weight over 68 weeks with semaglutide 2.4 mg weekly, and approximately 8% with liraglutide 3.0 mg daily. However, individual responses ranged widely, with some participants losing over 20% whilst others experienced minimal benefit.

Some imaging substudies have examined changes in visceral fat during GLP-1 receptor agonist treatment. These smaller studies suggest reductions in visceral adipose tissue alongside overall weight loss, though the magnitude varies between individuals. These changes often correlate with improvements in metabolic markers including HbA1c, fasting glucose, and triglycerides.

Typical timeline:

• Weeks 0–4: Initial appetite suppression and modest weight loss, primarily fluid and glycogen

• Months 2–6: Progressive weight loss with measurable reductions in waist circumference

• Months 6–12: Continued but often slower weight loss, with maximum effect typically achieved by 12–18 months

• Beyond 12 months: Weight maintenance phase; continued treatment generally required to sustain losses

It is essential to emphasise that GLP-1 medications are not a standalone solution. Optimal results require:

• Adherence to a reduced-calorie diet

• Regular physical activity (150+ minutes weekly of moderate intensity)

• Behavioural support and lifestyle modification

• Ongoing medical supervision

Weight regain commonly occurs following medication discontinuation, highlighting the chronic nature of obesity management.

Safety Considerations and Who Should Avoid GLP-1

Whilst GLP-1 receptor agonists demonstrate favourable efficacy for weight loss, they are not suitable for everyone and carry potential adverse effects that require careful consideration and monitoring.

Common adverse effects include:

• Gastrointestinal symptoms: Nausea, vomiting, diarrhoea, constipation, and abdominal discomfort affect 30–50% of users, particularly during dose escalation. These typically improve over 4–8 weeks but may necessitate slower titration or discontinuation

• Injection site reactions: Erythema, pruritus, or discomfort at injection sites

• Fatigue and dizziness: Reported by some patients, particularly initially

• Gallbladder disease: Rapid weight loss increases cholelithiasis risk; patients should be counselled about symptoms of biliary colic

Serious but rare adverse effects:

• Pancreatitis (discontinue immediately if suspected)

• Diabetic retinopathy complications (particularly in patients with pre-existing retinopathy and rapid glycaemic improvement)

• Acute kidney injury (usually in context of severe dehydration from vomiting/diarrhoea)

• Hypoglycaemia (particularly when used with insulin or sulfonylureas, which may require dose adjustment)

Contraindications include:

• Known hypersensitivity to the medication

• Pregnancy and breastfeeding (for semaglutide, discontinue at least 2 months before planned conception; check specific SmPC guidance for other agents)

Cautions and special considerations:

• Severe gastroparesis or gastrointestinal disease

• History of pancreatitis

• Renal impairment (specific guidance varies by agent; exenatide is contraindicated if eGFR <30 mL/min/1.73m², while others may be used with caution)

• Diabetic retinopathy requiring active treatment

Patients should contact their GP or seek urgent medical attention if they experience:

• Severe, persistent abdominal pain (possible pancreatitis)

• Persistent vomiting preventing oral fluid intake

• Visual changes

• Signs of allergic reaction

Regular monitoring should include weight, blood pressure, renal function, and glycaemic parameters in diabetic patients. Healthcare professionals and patients are encouraged to report suspected adverse reactions to the MHRA through the Yellow Card scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions