What Is a GLP-1 Medication? A Plain-English Guide

GLP-1 medications are the most significant development in obesity treatment in a generation. Mounjaro, Wegovy, Ozempic, Saxenda. They are all part of this class. But what exactly are they, and why do they work so differently from everything that came before?

What does GLP-1 stand for?

GLP-1 stands for glucagon-like peptide-1. It is a hormone produced naturally in your small intestine when food enters your gut. Its job is to signal your pancreas to release insulin, suppress glucagon (the hormone that raises blood sugar between meals), slow the passage of food through your stomach, and send fullness signals to the hypothalamus, the brain's appetite control centre.

Here is the key point: in many people with obesity, GLP-1 signalling is less effective. The body either produces less of the hormone or responds to it less efficiently. This can perpetuate overeating, not because of a lack of willpower, but because the biological feedback loop that creates the feeling of satiety is not functioning optimally.

What is a GLP-1 receptor agonist?

A GLP-1 receptor agonist is a medication that mimics GLP-1 by binding to the same receptors in your body, generating the same physiological responses, but more potently and for much longer. Natural GLP-1 has a half-life of only a few minutes. Pharmaceutical GLP-1 agonists are engineered to last days to weeks, providing sustained appetite suppression that the natural hormone simply cannot maintain.

Which medications are GLP-1 receptor agonists?

• Wegovy (semaglutide), licensed for weight management in the UK; once-weekly injection
• Ozempic (semaglutide), licensed for type 2 diabetes; the same molecule as Wegovy at lower doses
• Saxenda / Nevolat (liraglutide), licensed for weight management; once-daily injection
• Mounjaro (tirzepatide), dual GLP-1 and GIP receptor agonist; first of its class; most recently approved; currently the most potent in clinical trials

Note: Mounjaro is a dual agonist. It activates both GLP-1 and GIP receptors simultaneously. This additional mechanism gives it superior efficacy in clinical trials compared to GLP-1-only medications.

How GLP-1 medications produce weight loss

1. Appetite reduction: direct signals to the hypothalamus reduce your baseline hunger level
2. Slower gastric emptying: food moves more slowly through your stomach, extending the feeling of fullness after meals
3. Reduced food cravings: GLP-1 receptors in the brain's reward centres reduce the psychological pull of high-calorie foods; what patients often describe as "food noise" quietens significantly
4. Blood glucose stabilisation: prevents the spikes and crashes in blood sugar that drive hunger and cravings between meals

The result: patients eat substantially less, not through willpower, but because the biological drive to eat has been reduced. This is why clinical results so dramatically exceed what diet and exercise alone achieves.

"GLP-1 medications are addressing the underlying hormonal drivers of obesity, not just providing caloric guidance. This is why they produce results that dietary advice alone cannot replicate."

What conditions are GLP-1 medications used for in the UK?

Currently licensed for:

• Obesity and overweight: Wegovy and Mounjaro (BMI ≥30, or ≥27 with a weight-related condition)
• Type 2 diabetes: Ozempic and Mounjaro at lower doses
• Cardiovascular risk reduction: Wegovy holds a specific MHRA licence for reducing heart attack, stroke, and cardiovascular death risk in patients with established CVD (based on the SELECT trial, 2023)

Emerging research is also investigating GLP-1 medications for heart failure, non-alcoholic fatty liver disease, and neurodegenerative conditions.

Are GLP-1 medications safe long-term?

Semaglutide trial data now extends to over four years, and tirzepatide extension studies are ongoing. The safety profile is reassuring, gastrointestinal side effects are the most common, and these are concentrated during the dose escalation phase. The SELECT trial demonstrated that semaglutide actively reduces cardiovascular risk in high-risk patients. GLP-1 medications are not merely weight-neutral from a cardiac perspective. They are actively protective.

Who is eligible privately?

Adults with a BMI of 30 or above, or 27 or above with a weight-related health condition, can access Mounjaro or Wegovy privately through GPhC-registered pharmacies like Solira following a clinical consultation.