You've seen the headlines. You've heard the names — Ozempic, Mounjaro, GLP-1. But what exactly is GLP-1 therapy, how does it actually work, and is it right for you? This article explains the science behind these medications in plain language, and what it means for South Africans looking to manage their weight.
GLP-1 stands for glucagon-like peptide-1. It's a hormone that your gut produces naturally, every time you eat. When food reaches the small intestine, specialised cells release GLP-1 into your bloodstream. The hormone then does several important things:
In people with obesity or type 2 diabetes, these GLP-1 signals are often blunted or insufficient. The result: you feel hungry sooner, eat more, and your blood sugar regulation is impaired. GLP-1 medications correct this by providing a powerful, sustained version of the hormone signal your body should already be producing.
GLP-1 receptor agonists are engineered versions of the GLP-1 hormone, modified to last far longer in the body than the natural version (which breaks down within minutes). Ozempic and Mounjaro, for example, are designed to remain active for approximately seven days — which is why they're injected just once a week.
The result is a continuous, week-long signal to your brain and gut that significantly reduces hunger, increases feelings of fullness, and reduces the appeal of high-calorie foods. Many patients describe it as "food noise going quiet" — the constant background thoughts about food, snacking, and cravings simply diminish.
This is not willpower. This is biochemistry. GLP-1 medications work with your biology, not against it — and that's why their results are so substantially better than dieting alone.
| Medication | Active Ingredient | SAHPRA Status | Injection Frequency | Key Strength |
|---|---|---|---|---|
| Wegovy | Semaglutide 2.4 mg | Registered for weight management | Once weekly | Registered specifically for obesity |
| Ozempic | Semaglutide 0.5–2 mg | Registered (diabetes); off-label for weight | Once weekly | Well-established, widely available |
| Mounjaro | Tirzepatide | Registered in SA | Once weekly | Greatest weight loss in trials |
| Saxenda | Liraglutide | Registered for weight management | Daily | Registered specifically for obesity |
Note: Wegovy (semaglutide 2.4 mg, formulated specifically for weight management) is now SAHPRA-registered in South Africa. Ozempic (lower-dose semaglutide registered for diabetes) continues to be prescribed off-label for weight loss as well. Your doctor will advise on which semaglutide formulation is most appropriate for you.
GLP-1 therapy for obesity is backed by some of the most impressive clinical trial data in the history of weight management medicine. To put this in perspective:
Beyond weight loss, these medications have been shown to reduce cardiovascular events, improve blood pressure, lower HbA1c in diabetics, reduce liver fat in NAFLD, and improve PCOS markers. The cardiovascular benefit data (SELECT trial for semaglutide) was so compelling that many guidelines now recommend GLP-1 therapy for eligible patients regardless of weight loss goals alone.
This is the most common misconception about these medications. GLP-1 therapy is a medical treatment for a chronic condition — not a shortcut or a cheat. Obesity is a complex, chronic disease with strong genetic and hormonal drivers. Treating it with evidence-based medication is no different from treating hypertension with antihypertensives or diabetes with insulin.
Research shows that if patients stop GLP-1 therapy, weight typically returns — similar to what happens when you stop most chronic disease medications. This isn't a failure of the patient; it reflects the biological nature of obesity and the role these medications play in managing it.
For best results, GLP-1 therapy should be combined with reasonable attention to nutrition and physical activity — not because willpower is required, but because the medications work better when paired with healthy habits. The medications make those habits far easier to maintain by reducing hunger and cravings.
"GLP-1 medications are just for diabetics."
GLP-1 medications were originally developed for type 2 diabetes, but are now extensively used for weight management in non-diabetic patients. Saxenda and Mounjaro are registered for obesity. Ozempic is widely prescribed off-label for weight loss by registered SA doctors.
"You'll lose all your muscle, not fat."
GLP-1 therapy produces predominantly fat mass loss. Maintaining protein intake and engaging in resistance exercise (even light activity) preserves lean muscle mass. Most patients retain the majority of their muscle during treatment.
"These medications are dangerous and experimental."
Semaglutide has been studied in tens of thousands of patients across multiple large-scale clinical trials. These are among the most studied medications in recent pharmaceutical history. They are not experimental — they are well-established treatments with known safety profiles.
"You have to inject yourself every day."
Ozempic and Mounjaro are both once-weekly injections. The pen is pre-filled and the injection takes seconds. Most patients describe it as barely noticeable — the needle is very fine and injected subcutaneously into a fatty area.
The first few weeks are a dose-escalation phase — you start on the lowest dose to allow your body to adjust and minimise side effects. Most patients notice reduced appetite within the first week. Weight loss typically begins in weeks 2–4 and accelerates as the dose increases over the following months.
Side effects (mainly nausea) are most common in the first 4–8 weeks and improve significantly for most patients as the body adapts. The dose escalation schedule is designed specifically to minimise this. Most patients find that eating smaller meals, avoiding greasy or spicy foods, and staying hydrated during the adjustment phase greatly reduces discomfort.
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