Weight-Loss Injections: What You Really Need to Know
Over the past year, conversations about so-called “weight-loss jabs” have been everywhere — in newspapers, in office kitchens, in cafés, and probably even whispered between sets in the gym. It seems to be the number one conversation on social media in Jersey (well, a toss-up between that and whether B&Q is open). The spotlight here is mostly on Mounjaro and Ozempic, although there are others in the same family.
As someone who’s spent more than a decade working with people one-to-one as a personal trainer, I hear about these medications a lot. Clients ask me whether they work, whether they’re safe, and whether they’re “THE ANSWER.” That’s what prompted me to write this — not to advocate for or against them, but to cut through the noise. Because right now, it is deafening! On one side, miracle claims; on the other, horror stories. The truth, as usual, lies in between the two.
This isn’t medical advice. I’m not a doctor, and if you’re considering using these drugs you must speak to a qualified healthcare professional first. My aim here is simply to explain what the science actually says, and to help you think about where these medications might – and/or might not - fit into the bigger picture of health.
Why Exercise Still Matters
Let’s start with what I know best. Even if the scale is moving thanks to medication, exercise is not optional, even within the STEP and SURMOUNT-1 (Wegovy/Ozempic and Mounjaro) trials exercise was included [1, 2]. Without it, a significant portion of weight lost is likely to come from muscle mass rather than fat. Less muscle means a slower metabolism, poorer strength, far less interesting shapes on our bodies, and outcomes that rarely last.
Strength training is especially important. Muscle isn’t just about looks — it underpins mobility, balance, and long-term health. Cardiovascular exercise adds another layer, supporting heart health, mood, and energy. Together, they improve not just weight loss, but quality of life.
Think of it this way: medication may turn down the volume on hunger, but exercise shapes what your body actually becomes in response. Without purposeful movement, it’s like building a structure on quicksand.
Exercise remains the anchor for lasting results and having guidance when establishing new habits can make it far easier to stay on track and see meaningful improvements.
The Science Behind the Jabs
These drugs weren’t originally developed for weight management. They were designed for type 2 diabetes. But researchers noticed during trials that participants consistently lost weight — not through willpower, but because the drugs changed how their bodies regulated hunger.
Here’s how they work:
· GLP-1 (glucagon-like peptide-1): signals fullness to the brain, slows stomach emptying, and helps regulate blood sugar.
· GIP (glucose-dependent insulinotropic polypeptide): works with GLP-1 to regulate appetite and insulin.
Semaglutide (Ozempic/Wegovy) mimics GLP-1, increasing satiety and slowing digestion. Tirzepatide (Mounjaro) activates both GLP-1 and GIP receptors, which may explain why trials show even greater weight loss.
The outcome: people feel full sooner and for longer, making it easier to eat fewer calories without constant hunger.
What the Evidence Shows
The clinical trial results are impressive:
· The STEP trials of semaglutide (Wegovy) showed an average weight loss of ~15% of body weight over 68 weeks, when combined with lifestyle support [1].
· The SURMOUNT-1 trial of tirzepatide (Mounjaro) reported weight loss of up to 22.5% over 72 weeks [2].
But notice the wording: “average” and “up to.” Not everyone achieved dramatic results, and the most striking figures represent the upper end of the scale.
It’s also critical to highlight that participants weren’t just given injections. They also received diet, exercise, and behaviour support. The medication wasn’t a standalone solution — results were best when paired with lifestyle changes.
Who They’re Designed For
These medications are not for casual use or quick-fix goals. Guidelines recommend them for adults with obesity (BMI ≥30), or overweight adults (BMI ≥27) who also have a weight-related condition such as diabetes, hypertension, or sleep apnoea [3].
They are not advised for people with a history of medullary thyroid carcinoma, Multiple Endocrine Neoplasia type 2, pancreatitis, or for those pregnant or breastfeeding [4]. This is why professional medical oversight is non-negotiable.
Side Effects and How to Manage Them
The most common side effects are gastrointestinal: nausea, bloating, constipation, diarrhoea, or abdominal pain. These often improve with time or dosage adjustments.
Rare but more serious risks include pancreatitis, gallbladder problems, and kidney issues – which are usually linked to dehydration. Animal studies raised concerns about thyroid tumours, but this hasn’t been proven in humans [5].
Practical strategies help ease symptoms:
· Eat slowly and stop before feeling overly full.
· Prioritise protein to preserve muscle and support satiety.
· Include fibre (vegetables, pulses, wholegrains) to reduce constipation.
· Stay hydrated to support digestion and kidney function.
· Keep exercising — it aids digestion, protects muscle, and supports overall health.
The thing that I find the most interesting is that these habits are the same ones that underpin sustainable fat loss without medication.
How Long Do You Need to Take Them?
GLP-1s are not short-term fixes. The STEP-1 extension trial showed that participants regained two-thirds of their lost weight within a year of stopping semaglutide [6].
This doesn’t mean the drugs don’t work. It means they only work while taken — unless lifestyle habits change alongside them. Doctors often frame them as long-term treatments, not quick resets.
If someone does plan to stop, it must be tapered under medical supervision. And the best defence against rebound weight gain? Consistent nutrition, hydration, and exercise habits built along the way.
The Bigger Picture
So, is it worth it? These injections are powerful tools — but only tools. They target appetite regulation, but they don’t build strength, fitness, or resilience. That’s where lifestyle comes in.
Used wisely, these drugs can create breathing space: less noise from hunger, more capacity to put healthy habits in place. But the long-term win doesn’t come from the
injection itself. It comes from what you do with that space: nourishing your body, moving with purpose, and building habits. And while professional guidance isn’t mandatory, it can be helpful to have someone guide you safely through exercise and habit-building, ensuring that the time and effort you invest delivers lasting results.
Final Thoughts
Weight-loss jabs aren’t miracle cures. They’re effective, evidence-based, and sometimes life-changing. But they’re also expensive, long-term, and not without risk.
The strongest results happen when they’re paired with the fundamentals: protein, fibre, hydration, and especially exercise. That’s the part that transforms numbers on a scale into real, lasting improvements in health, strength, and confidence.
If you’re considering these medications, consult your doctor. And if you do go ahead, use the opportunity wisely. Let exercise and lifestyle changes be the foundation. That’s where the future-proof results are found.
References
4. FDA. “Ozempic (semaglutide) Prescribing Information.” 2023.