Ozempic, Wegovy, and GLP-1 for long-term weight loss

The clinical evidence behind GLP-1 weight loss

In the STEP 1 trial published in the New England Journal of Medicine, patients on semaglutide 2.4 mg lost an average of 14.9% of their body weight over 68 weeks, roughly six times more than the diet-and-exercise group. That is not a marginal improvement. For someone weighing 90 kg, it translates to approximately 13 kg lost. Results like these have made GLP-1 medications such as Ozempic, Wegovy, and Rybelsus the most talked-about weight loss treatment in Singapore and globally.

But headlines only tell part of the story. What matters for anyone considering weight loss medication is whether those results hold up over time, how different GLP-1 options compare, and what the experience of treatment actually looks like. This guide covers exactly that, from clinical trial data and a head-to-head comparison of semaglutide and tirzepatide, to who qualifies for treatment in Singapore, what side effects to expect, and how to get started.

What are GLP-1 medications?

Glucagon-like peptide-1 (GLP-1) medications are a class of prescription weight loss treatment that mimic a natural hormone your body already produces. After you eat, your gut releases GLP-1 to signal fullness. The problem is that this natural hormone breaks down within minutes. Medications like semaglutide (the active ingredient in Ozempic, Wegovy, and Rybelsus) are engineered to resist that breakdown, so the fullness signal stays active for days rather than minutes.

GLP-1 medications were originally developed for Type 2 diabetes management. Ozempic and Rybelsus are still primarily prescribed for blood sugar control. Wegovy uses the same molecule (semaglutide) at a higher dose specifically approved for weight management. The distinction matters: while Ozempic is sometimes prescribed off-label for weight loss, Wegovy is the formulation purpose-built for it.

Tirzepatide (marketed as Mounjaro and Zepbound) takes the concept further. It is a dual GLP-1 and GIP receptor agonist, sometimes called a "twincretin", that activates two hormonal pathways simultaneously, which is why its weight loss results have exceeded even semaglutide in clinical trials.

For a broader overview of available medications, see our guide to weight loss medication.

How GLP-1 medications work for weight loss

GLP-1 medications produce weight loss through three main mechanisms.

Appetite suppression. Semaglutide and tirzepatide cross the blood-brain barrier and act on the hypothalamus, the brain's appetite control centre. They activate POMC/CART neurons (which produce satiety) and suppress NPY/AgRP neurons (which drive hunger). The net result is a dramatic reduction in what patients often call "food noise", that constant mental preoccupation with food that makes every diet feel like a battle of willpower.

Delayed gastric emptying. These medications slow the rate at which food leaves your stomach, which means you feel physically full for longer after each meal. This is one reason many patients naturally shift to smaller portions without conscious restriction.

Improved metabolic signalling. GLP-1 medications enhance glucose-dependent insulin secretion, suppress glucagon, and improve insulin sensitivity. This helps stabilise blood sugar and reduces the sharp dips that trigger intense cravings, particularly relevant for anyone with insulin resistance, PCOS, or prediabetes.

The combined effect is that patients eat less without fighting constant hunger. That is what separates GLP-1 treatment from traditional dieting: it addresses the biological drivers of overeating rather than relying on willpower alone.

Ozempic vs Wegovy vs Rybelsus: comparing GLP-1 medications

One of the most common questions about weight loss medication in Singapore is how the available options compare. Here is a breakdown of the main GLP-1 medications and tirzepatide.

Ozempic is the most widely recognised brand name and the one most people search for when researching weight loss injections. It contains semaglutide at doses up to 2.0 mg and is technically approved for diabetes, though doctors in Singapore may prescribe it off-label for weight management. Its weight loss results are substantial, though slightly lower than Wegovy due to the lower maximum dose.

Wegovy is semaglutide at the full 2.4 mg weight management dose. The dosing schedule starts at 0.25 mg weekly and titrates gradually over 16 weeks, 0.5 mg, then 1.0 mg, then 1.7 mg, reaching 2.4 mg at week 17. This slow titration is key to minimising side effects. Wegovy availability in Singapore (often searched as "Wegovy SG") has been expanding, though supply can fluctuate.

Rybelsus is the oral semaglutide option, a daily weight loss pill rather than an injection. At its current approved dose of 14 mg, Rybelsus for weight loss produces more modest results (around 3-5% body weight reduction based on the PIONEER trials). However, higher-dose oral formulations currently in trials are showing much stronger results: 13.6% weight loss at 25 mg (OASIS 4 trial, 64 weeks) and 15.1% at 50 mg (OASIS 1 trial, 68 weeks). For a detailed comparison, read our article on oral vs injectable GLP-1 options.

Tirzepatide has delivered the strongest weight loss results of any GLP-1 medication to date. In the SURMOUNT-1 trial, the 15 mg dose achieved 20.9% mean body weight reduction over 72 weeks (intention-to-treat analysis). It works by activating both GLP-1 and GIP receptors, though it is injection-only.

Clinical trial results: what the data shows

GLP-1 weight loss evidence goes well beyond a single headline figure. Here are the key trials that inform treatment decisions.

STEP 1 (semaglutide 2.4 mg, 68 weeks)

This trial enrolled adults with overweight or obesity without diabetes. At 68 weeks, mean weight loss was 14.9% (Wilding et al., NEJM 2021). The response distribution matters just as much as the average:

• 86.4% of participants lost more than 5% of their body weight
• 69.1% lost more than 10%
• 50.5% lost more than 15%
• 32% lost more than 20%

These are not averages propped up by a few extreme responders. The majority of patients achieved clinically meaningful weight loss.

STEP 5 (long-term semaglutide data, 104 weeks)

The two-year STEP 5 trial showed that weight loss is sustained with continued treatment. Participants on semaglutide 2.4 mg achieved 15.2% mean weight loss at 104 weeks (Garvey et al., Nature Medicine 2022), compared to 2.6% in the placebo group. On top of that, 80% of participants who started with prediabetes returned to normal blood sugar levels.

SURMOUNT-1 (tirzepatide, 72 weeks)

Tirzepatide showed dose-dependent results across three treatment arms:

• 5 mg: 15.0% weight loss (ITT)
• 10 mg: 19.5% weight loss (ITT)
• 15 mg: 20.9% weight loss (ITT)

At the highest dose, 39.7% of participants achieved at least 25% weight loss (efficacy estimand, on-treatment analysis). No other weight loss medication has matched those numbers.

SELECT trial (cardiovascular outcomes, 208 weeks)

Beyond weight, the SELECT trial showed that semaglutide reduced major adverse cardiovascular events (MACE), including heart attacks and strokes, by 20% over four years. Participants maintained an average 10.2% weight loss throughout the study period. That four-year durability data is some of the strongest evidence that GLP-1 treatment works long-term.

Who qualifies for GLP-1 treatment in Singapore

In Singapore, GLP-1 medications are prescription-only and require a doctor's assessment. Eligibility depends on your BMI and overall health profile.

MOH clinical practice guidelines for pharmacotherapy:

• BMI of 30 or above: eligible for weight loss medication without additional conditions
• BMI of 27.5 to 29.9: eligible if you have weight-related comorbidities such as Type 2 diabetes, hypertension, or high cholesterol

Trimly's eligibility criteria:

• BMI of 27.5 or above without weight-related conditions
• BMI of 24 or above with weight-related conditions (Type 2 diabetes, hypertension, PCOS, etc.)

To put those numbers in perspective: for a woman who is 160 cm tall, a BMI of 24 is approximately 61 kg, and a BMI of 27.5 is approximately 70 kg.

There are some important contraindications. GLP-1 medications are not suitable if you are pregnant or breastfeeding, or if you have a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Your doctor will review your full medical history during the consultation.

For a detailed breakdown of the assessment process, see our article on how to qualify for medical weight loss treatment.

What to expect: the weight loss timeline

Here is what typically happens month by month.

Weeks 1-4 (dose titration starts). You begin on a low dose, for Wegovy, this is 0.25 mg weekly. Weight loss during this phase is typically modest (1-2 kg), but most patients notice a significant reduction in food noise and appetite within the first two weeks. The low starting dose is deliberate: it allows your body to adjust gradually, which helps minimise gastrointestinal side effects.

Weeks 4-12 (building to therapeutic dose). As the dose increases through the titration schedule, weight loss accelerates. By weeks 8-12, most patients see a reduction of 5-10% of their starting body weight. This is the phase where changes become visible, clothes fit differently, energy levels improve, and the relationship with food begins to shift.

Months 3-12 (steady progress). Weight loss continues at a steady rate of approximately 1-2% of body weight per month. Clinical data shows that most of the total weight loss occurs within the first 12 months of treatment. Combining medication with regular exercise, even moderate activity like 150 minutes of walking per week, enhances both fat loss and muscle preservation.

Year 1 and beyond (maintenance). The STEP 5 trial showed that weight loss plateaus around the one-year mark and is then maintained with continued treatment. At 104 weeks, participants maintained a 15.2% reduction. The SELECT trial confirmed durability out to four years, with 10.2% sustained weight loss.

An important note on discontinuation: the STEP 1 extension data showed that nearly two-thirds of weight lost was regained within a year of stopping treatment. This is not a failure of the medication. It reflects the fact that obesity involves persistent biological changes in hunger and metabolism. For many patients, ongoing treatment is the most effective approach, much like using medication to manage blood pressure or cholesterol. Your doctor will work with you to determine the right long-term plan.

Side effects and how to manage them

GLP-1 medications have a well-established safety profile, but side effects, particularly during the dose titration phase, are common. Knowing what to expect makes them much easier to manage.

Gastrointestinal effects (most common). Nausea, vomiting, diarrhoea, and constipation are the most frequently reported side effects. In clinical trials, nausea affected roughly 40-45% of semaglutide patients, though it was typically mild to moderate and resolved within the first few weeks. Practical management strategies include:

• Eating smaller, more frequent meals
• Avoiding high-fat, greasy, or spicy foods
• Staying well hydrated
• Having ginger tea or plain crackers to ease nausea
• Increasing fibre and fluid intake if constipation occurs

Injection site reactions (for weight loss injections). Mild redness, swelling, or itching at the injection site can occur with Wegovy, Ozempic, or tirzepatide. Rotating injection sites between the abdomen, thigh, and upper arm helps minimise this.

Rare but serious effects. Pancreatitis (severe, persistent abdominal pain), gallbladder complications, and kidney issues are uncommon but require immediate medical attention. If you experience severe abdominal pain, yellowing of the skin, or inability to pass gas or move your bowels, contact your doctor right away.

The gradual dose titration exists to minimise side effects. Regular follow-ups with your doctor allow for dosage adjustments if needed, which is why medical supervision matters. For a comprehensive guide to managing side effects, read our article on common GLP-1 side effects and how to manage them.

Cost of GLP-1 treatment in Singapore

Price transparency matters, especially when many clinics in Singapore separate consultation fees, medication costs, and follow-up charges.

GLP-1 medication costs in Singapore vary depending on the specific medication, dosage, and provider. Some clinics charge $100-200 for the initial consultation, with medication costs on top. Others bundle everything into a single monthly fee.

At Trimly, treatment plans range from $350 to $650 per month, with everything included: doctor consultation, medication, home delivery, and unlimited free follow-up appointments. There are no hidden consultation fees or surprise charges. This all-in pricing is designed so you know exactly what to budget from day one.

A few things worth noting about semaglutide in Singapore:

• GLP-1 medications prescribed for weight loss are generally not covered by Medisave or standard health insurance
• Ozempic may be partially claimable if prescribed for Type 2 diabetes with a BMI of 27.5 or above, check with your insurer
• Coverage rules are evolving, so it is worth asking your provider about the latest options

Compared to the cumulative cost of gym memberships, supplements, meal delivery services, and repeated diet programmes, medically supervised GLP-1 treatment often represents better value, particularly when you factor in the clinical evidence behind it.

Getting started with GLP-1 treatment at Trimly

Trimly is a MOH-licensed telehealth clinic in Singapore focused exclusively on GLP-1 weight loss treatment. Here is how the process works.

1. Complete the online questionnaire. A short health assessment covers your medical history, current medications, weight loss goals, and any relevant conditions. This takes about two minutes.

2. Book a video consultation. A licensed Singapore doctor reviews your profile and conducts a video consultation to assess your suitability for treatment. They will discuss your options, including whether oral or injectable GLP-1 is the better fit for your situation, and answer any questions.

3. Receive your personalised treatment plan. If you qualify, your doctor creates a tailored plan with the appropriate medication and dosing schedule. Your medication is delivered to your door.

4. Ongoing support and follow-ups. Unlimited free follow-up consultations are included in your plan. Your doctor monitors your progress, adjusts dosages as needed, and provides responsive support via WhatsApp. This is not a one-time prescription. It is continuous, doctor-led care.

Trimly offers both oral GLP-1 (daily weight loss pills) and injectable GLP-1 (weekly weight loss injections), with treatment plans starting from $350 per month. Whether you are searching for Ozempic in Singapore, exploring Wegovy SG availability, or considering Rybelsus for weight loss, the first step is the same: a conversation with a doctor who can help you find the right approach.

Key takeaways

GLP-1 medications have changed weight loss treatment. The clinical evidence is clear: 14.9% weight loss with semaglutide (STEP 1), 20.9% with tirzepatide (SURMOUNT-1), and long-term data showing these results hold up with continued treatment.

What makes GLP-1 treatment different from everything you may have tried before is that it works at the hormonal level. It reduces food noise and curbs appetite biologically, giving you the space to build healthier habits without constantly fighting your own body.

If you have been considering weight loss medication in Singapore, whether you have been researching Ozempic, Wegovy, semaglutide, or weight loss pills that actually work, the most important step is getting a proper medical assessment. Every person responds differently, and the right medication, dose, and support plan make all the difference.

Trimly's MOH-licensed doctors can help you figure out if GLP-1 treatment is the right fit, all from home, with transparent pricing and unlimited follow-ups.

Frequently asked questions

How much weight can I lose on Ozempic or Wegovy?

Clinical trial data shows an average of 14.9% body weight reduction with semaglutide 2.4 mg (Wegovy) over 68 weeks. In the STEP 1 trial, 86.4% of participants lost more than 5% of their body weight, and 32% lost more than 20%. Ozempic, which uses a lower maximum dose, typically produces slightly less weight loss. Individual results vary depending on factors like starting weight, adherence, diet, and exercise.

Is Ozempic available in Singapore?

Yes. Ozempic (semaglutide) is available by prescription in Singapore. It is officially approved for Type 2 diabetes, though doctors may prescribe it off-label for weight management. Wegovy (semaglutide at the 2.4 mg weight loss dose) is also increasingly available in Singapore. A doctor's consultation is required to determine which option is appropriate for your situation.

What is the difference between weight loss pills and weight loss injections?

The main GLP-1 weight loss pill is Rybelsus (oral semaglutide), taken daily. At its current 14 mg dose, it produces more modest weight loss (approximately 3-5%) compared to injectable options like Wegovy (14.9%) or tirzepatide (up to 20.9%). However, higher-dose oral formulations in clinical trials are closing this gap. Weight loss injections (Wegovy, Ozempic, tirzepatide) are administered once weekly and generally produce stronger results. Your doctor can help you decide which format suits your preferences and health goals.

Do I need to stay on GLP-1 medication forever?

Not necessarily, but ongoing treatment often produces the best long-term results. The STEP 1 extension data showed that nearly two-thirds of weight lost was regained within a year of stopping semaglutide. This is because obesity involves persistent changes in hunger hormones and metabolism. Many patients choose to continue treatment long-term, similar to how blood pressure medication is managed. Your doctor will work with you to find the right approach. Some patients maintain their results with lifestyle changes alone, while others benefit from continued medication support. Read more about maintaining weight after GLP-1 treatment.