Ozempic, Mounjaro, and the GLP-1 Revolution: A Pharmacist's Honest Take

I remember the first time I reviewed a patient prescribed a GLP-1 agonist for their diabetes management. They had only been taking it for 4 months but they had already seen a meaningful reduction in their HbA1c reading and noticeable reduction in their weight. 

I remember thinking how this drug might actually do something to steer the ship of diabetes management and remission back on track.

She was in her early sixties. Type 2 diabetes for almost a decade. A succession of tablets had kept her HbA1c in a broadly acceptable range, but nothing had shifted the underlying trajectory. She was not sedentary. She was not disengaged from her care. She was a patient managing a disease that had got ahead of her.

But the thing she said, almost as she was leaving, is the line I still come back to.

"I’m not eating as much as I used to. I’ve dropped down to two meals a day” 

I admit that I dismissed the notion of appetite suppression at first. If I knew then that it is that exact pharmacological mechanism that would see Novonordisk, the pharmaceutical company behind Ozempic and Wegovy, become Europe’s most profitable company in 2023…. I would have bought shares.

What follows is where I have got to on these medications. Spoiler - it is a huge distance from where I started.

What nobody explains properly

GLP-1 stands for glucagon-like peptide 1. It is a hormone produced in your gut after eating, and it does several things at once. It prompts insulin release from the pancreas. It slows gastric emptying. It reduces liver glucose output. And crucially, it sends satiety signals to the brain that tell you the meal is over. [1] [2]

The problem in obesity and in type 2 diabetes is that this signalling system is often dysregulated. The brain becomes less responsive to satiety signals. Appetite becomes harder to override by choice. The biological defence of a higher body weight is far more active than most people appreciate. The theory of biological set point and leptin resistance is intriguing but one for a different blog post.

GLP-1 receptor agonists work by mimicking this hormone at concentrations higher and more sustained than the body would naturally produce. They have a half-life of 5-days; the time taking for the body to reduce the concentration of the drug by half. This helps the drug carry out its sustained suppression of appetite but they are not appetite suppressants in the old stimulant sense - we no longer give amphetamine to chubby people - but instead they are recalibrating a signalling pathway.

Each month in my private weight loss clinic, I prescribe and dispense enough of these prescriptions to notice what patients say when they come back. The pattern is consistent: less preoccupation with food, smaller portions without effort, a quieter relationship with eating. That is exactly what a recalibrated satiety signal looks like in practice, and it is unlike anything I have heard patients describe before.

A powerful description that I have heard from several of my patients now is that “it is like someone has flicked a switch in my head and turned off all the food noise”.

The patient who told me she was not thinking about food the way she used to was not exercising more willpower. She was experiencing a genuinely different hormonal environment. 

Semaglutide, the active ingredient in Ozempic and Wegovy, is a weekly injection. In the STEP 1 trial, participants lost around 15-16% per cent of body weight on average. [3] More significantly, the SELECT trial, published in 2023, demonstrated a 20 per cent reduction in major cardiovascular events in people with pre-existing cardiovascular disease and obesity but without diabetes. [4] That is not a metabolic footnote. That is a true mortality reduction.

Tirzepatide, sold as Mounjaro, goes further still. It acts on both GLP-1 and GIP receptors simultaneously. GIP is another gut hormone involved in appetite and fat storage, and the dual action appears to produce greater weight loss than GLP-1 alone. The SURMOUNT trials showed average weight reductions of around 20-21% per cent, with some cohorts losing considerably more. [5] These are results that, a decade ago, would have seemed implausible for any pharmacological intervention. These sort of results are closer to the expected benefits of surgical intervention such as gastric bypass.

Who they are actually for

This is where the clinical story and the social media story begin to diverge quite sharply.

In the UK, Ozempic is licensed for type 2 diabetes management. Wegovy is licensed for weight management in adults with a BMI of 30 or above, or 27 and above if weight-related comorbidities are present. Mounjaro is now licensed for both indications.

NICE guidance for NHS prescribing sits within specialist weight management services, alongside documented comorbidities and structured behavioural support. The intention is a comprehensive clinical programme, not simply a prescription written at an online consultation.

The private market operates with considerably more variation. Patients can access these medications through online clinics, in some cases with limited clinical assessment and limited ongoing monitoring. This does not automatically mean unsafe prescribing. But it creates conditions where clinically important considerations can fall through the gaps.

These medications have real contraindications. A personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 is an absolute contraindication. Previous pancreatitis requires careful clinical consideration before prescribing. Patients already taking sulfonylureas or insulin need active glucose monitoring because the combination can push blood sugar uncomfortably low. It is often avoided in combination for this exact reason.

The question your online consultation may not be asking clearly enough: who is this not for?

What I actually see at the counter

Side effect profiles in clinical trials look manageable on paper. Gastrointestinal events predominate. Nausea, vomiting, diarrhoea, constipation, with the reassurance that these typically improve with slow dose titration.

The clinical reality is somewhat messier than that.

Nausea in the first eight to twelve weeks can be significant enough to affect daily functioning. Patients who push titration faster than recommended, often because they are paying privately and want results quickly, tend to experience the worst of it. I have had patients come back to the counter after several weeks, looking genuinely worn down, and ask whether this is supposed to happen. The honest answer: side effects are common, not universal, and for most people it does improve but there are some patients who simply cannot tolerate these medications and they need to stop taking them.

There is also a growing conversation about muscle mass that deserves more attention than it typically receives. Rapid weight loss of any kind carries a risk of lean tissue depletion. Some studies suggest that GLP-1 medications may result in a higher proportion of lean tissue loss than lifestyle-driven weight reduction, though findings vary considerably depending on protein intake and exercise habits. This is an area of active research, not settled consensus. What is broadly agreed is that adequate protein intake and resistance training are the right clinical mitigations, and both deserve to be built into the prescribing conversation far more consistently than they currently are. 

My honest first instinct

I will be straightforward about where I started with all of this.

When these prescriptions started arriving in meaningful volume, my gut response was scepticism. Not about the pharmacology, which I found genuinely interesting. My scepticism was more philosophical. More clinical, in the deepest sense of the word.

My professional life is spent watching the downstream consequences of the lifestyle most people lead. I believe in the foundational pillars of health not because they are fashionable but because I see what happens when they are absent, compounded over decades, by which point the conversation about prevention has become academic.

My concern was direct: would these medications become the medical equivalent of a reason not to bother? Would patients take the injection and feel, quite reasonably, that the work was being done on their behalf? Would the system reach for the drug before it had exhausted the case for the behaviour?

What changed

The most important shift was accepting, more fully than I had before, that obesity is not primarily a motivational failure.

I knew this intellectually. Most people in healthcare do, at least in principle. But there is a version of the lifestyle medicine perspective that, without intending to, slides into an implied accountability. Prevention as personal responsibility is correct and important. It can also, applied without sufficient acknowledgement of the biology, become a framing that does not quite match what is actually happening.

The defence of a higher body weight is active, not passive. After significant weight loss, leptin falls, ghrelin rises, metabolic rate adapts downward, and the body mounts a sustained biological effort to restore what it has lost. [6] The failure rates for long-term weight maintenance after significant loss are not a reflection of character. They are a reflection of physiology. 

The SELECT cardiovascular data was the thing that settled it for me most clearly. A 20 per cent reduction in serious cardiovascular events in a high-risk population [4] is not a wellbeing finding. It is a mortality finding. These drugs are treating a disease with real downstream consequences. The shortcut framing no longer held up. Beyond cardiovascular events, these drugs are showing promising preliminary data in reducing the progression of Alzheimer’s disease and certain types of cancers. These drugs are truly revolutionary in the truest sense of the word.

I still believe the lifestyle fundamentals matter. I still believe the patients who benefit most from these medications are the ones who use the reduced appetite and improved energy as a foundation to build different habits and reset their relationship to diet and exercise. But I no longer think those two positions are in opposition to one another, I see them as supportive of each other.

The part that genuinely concerns me

While the conversation about licensed GLP-1 medications has matured considerably, a parallel and significantly more alarming market has grown alongside it.

Retatrutide is a next-generation agent acting on GLP-1, GIP, and glucagon receptors simultaneously. Phase 2 trial data suggests weight loss approaching 25 per cent of body weight. [7] It is not licensed anywhere in the world. It has not completed Phase 3 trials. It is not approved for human use outside of controlled research settings.

It is being sold openly online and via social media accounts, marketed as a research chemical or laboratory use peptide, to anyone willing to buy it.

The risks are not theoretical. Unregulated injectable peptides carry no manufacturing standards, no sterility guarantee, no labelling accuracy, and no quality control. You do not know what concentration is in the vial. You do not know what else is in the vial. You have none of the clinical monitoring that would catch an adverse reaction early.

People have been hospitalised following use of research peptides purchased from these sources. Contamination, dosing errors, injection site infections, dangerous interactions in patients already taking other medications. These are not edge cases. They are the predictable consequences of injecting an unlicensed substance sourced from the internet, without prescription, without oversight, without any of the safeguards that exist for a reason.

I am a pharmacist governed by the GPhC. I have dispensed enough prescriptions to know that licensed medications, manufactured to pharmaceutical standards, used with clinical oversight, still carry real risks. The idea of removing every single one of those safeguards simultaneously is something I cannot present as anything other than dangerous.

If you are considering it, please do not. If someone you know is, please have the conversation.

What comes next

There is a meaningful limitation built into the current generation of these medications: they are injections. This creates a barrier for some patients who are needlephobic, affects long-term adherence, and complicates maintenance regimens.

The discontinuation data is fairly consistent. A significant proportion of lost weight returns when these medications are stopped, [8] reflecting the biological reality that the drug was managing the hormonal environment rather than changing it permanently. This does not mean the medications have failed. It does mean that the conversation about maintenance is just as important as the conversation about initiation.

Two oral alternatives are progressing through development in ways worth understanding.

Oral semaglutide already exists as Rybelsus, the tablet formulation licensed for type 2 diabetes management. An oral version specifically for weight management (oral wegovy) has been moving through the regulatory pipeline, addressing the bioavailability challenges and showing promising results. These tablets are expected to hit the UK market in 26/27.

Orforglipron represents a different approach altogether. It is a small molecule GLP-1 receptor agonist, not a peptide, which means it does not require the specialist absorption technology that injectable semaglutide depends upon. Early data from Eli Lilly's development programme has been encouraging, with a daily oral dose requiring no refrigeration and no injection training. [9] If Phase 3 results are sustained, this could meaningfully change the maintenance conversation for a much wider population. [10] The data from the trial shows that these drugs produce slightly greater HbA1c and weight loss reduction compared to oral semaglutide of comparable strengths but also the drop out rate due to side effects is higher. This is where a clinician actively involved in your care is priceless - a voice to actively compare and balance the goal of weight reduction with clinically meaningful harms.

Where I land

These medications have changed how I think about obesity treatment. Not because they are a solution in themselves, but because they are a useful and increasingly well-evidenced tool. For the right patient, within the right clinical framework, these drugs are literal lifesavers. 

There is one dimension of this conversation I want to name before I close, because I think it deserves more attention than it receives. These drugs cost thousands of pounds per patient per year. The NHS is prescribing them within specialist pathways, where capacity is limited and waiting lists are long. Private prescription is, in practice, the primary access route for most patients right now. That means a public health intervention aimed at a population-level disease is largely inaccessible to anyone without the means to go private. That is a genuinely uncomfortable position. A 20 per cent reduction in cardiovascular events should not be rationed by bank balance, and I think the NHS and government should have the bravery and decisiveness to roll out access to these drugs more rapidly than they currently are.

That is a more generous framing of the drugs themselves than where I started. And a more honest account of the system they sit within.

Have you been prescribed one of these medications, or are you considering it? Is there a question this post has not answered that you want me to look at? Drop it in the comments, or come and find me on Instagram and TikTok at @jakelifestylepharmacist.

Stay healthy,

Jake Groves
Pharmacist
Dose of Longevity