Key Takeaways
- GLP-1 medications work by influencing appetite, fullness and digestion, which can help reduce food intake and support weight loss as part of a broader weight management approach.
- Clinical trials have shown meaningful average weight loss, but results vary between individuals. The amount of weight lost depends on factors including the medication used, duration of treatment, individual health factors and accompanying lifestyle changes.
- GLP-1 based treatments are not all the same or suitable for everyone. Their mechanisms, approved uses, dosing and potential side effects differ, making individual suitability an important consideration.
- Weight management should look beyond the number on the scale. As an endocrinologist, Dr Vikram considers metabolic health, underlying medical conditions and longer term management when assessing whether GLP-1 based treatment may be appropriate.
GLP-1 medication has become one of the most talked-about options for medical weight management in recent years. Originally developed for the management of type 2 diabetes, certain GLP-1 based medications are now also used in the treatment of obesity and weight related health conditions.
But how does GLP-1 actually help with weight loss, how much weight can someone realistically expect to lose, and what happens when treatment is stopped? Understanding how these medications work, their limitations and who they may be suitable for is important before considering them as part of a weight management plan.
What Is GLP-1 and How Does It Work for Weight Loss?
GLP-1 (glucagon-like peptide-1) is a hormone naturally produced in the gut that helps regulate blood sugar and appetite. GLP-1 receptor agonists are a type of weight loss medication that mimic this hormone, helping to:
- Slow down stomach emptying, which increases feelings of fullness
- Reduce appetite and food cravings
- Improve blood sugar regulation
- Support gradual, sustained weight loss when combined with lifestyle changes
Most GLP-1 medications are administered by injection, which is why they are commonly referred to as “weight loss injections”. Semaglutide is one of the most widely studied GLP-1 receptor agonists and is the active ingredient in medications such as Ozempic and Wegovy. While both contain semaglutide, they are used at different doses and for different approved indications. Semaglutide has been studied for weight management in people with obesity or who are overweight with certain weight related health conditions.
What Does the Research Say About GLP-1 and Weight Loss?
Clinical trial data on semaglutide for weight management has shown meaningful average weight loss compared to placebo, though individual results vary considerably. For people wondering how much weight can you lose on GLP-1 medication, broadly, research has shown:
- Average weight loss in the range of 12–15% of starting body weight over roughly 68 weeks of treatment in clinical trials, when combined with diet and exercise support
- Greater weight loss with higher maintenance doses, up to a point
- Weight loss that tends to occur gradually over months, rather than rapidly
- Results that plateau over time as the body adjusts, which is why long-term treatment plans typically include maintenance strategies
It’s worth noting that these are average trial results, not guarantees. Some patients lose significantly more, others less, and results are strongly influenced by adherence to treatment and accompanying lifestyle changes.
What Affects How Much Weight You Lose?
Several factors influence individual results with GLP-1 medications, including semaglutide:
- Starting body weight – Patients with a higher starting BMI often see greater absolute weight loss, though percentage loss varies by individual.
- Dosage and duration – Treatment typically starts at a low dose that is gradually increased over several weeks to reduce side effects, with results building over months rather than weeks.
- Diet and physical activity – Clinical trials consistently combine GLP-1 treatment with dietary counselling and exercise, and real-world results tend to be strongest when patients follow similar lifestyle support alongside medication.
- Consistency of use – GLP-1 medications are typically administered as a weekly injection. Missed doses or early discontinuation can affect overall results.
- Individual metabolic and health factors – Underlying health conditions, metabolism, and genetics all play a role in how an individual responds to treatment.
What Are the Side Effects?
Like all medications, GLP-1 receptor agonists carry potential side effects, which should be discussed with a doctor before starting treatment. Commonly reported side effects include:
- Nausea, particularly when starting treatment or increasing dosage
- Vomiting or diarrhoea
- Constipation
- Fatigue
- Reduced appetite
Side effects can vary between individuals and may be more noticeable when treatment is first started or when the dose is being adjusted. While commonly reported gastrointestinal side effects may improve over time for some people, GLP-1 medications can also carry less common but potentially serious risks. Medical history, existing health conditions and how well the medication is tolerated should therefore be considered throughout treatment.
Is GLP-1 Medication Right for Everyone?
GLP-1 medications for weight management are generally considered for patients who meet specific clinical criteria, such as a BMI within the obesity range, or a lower BMI accompanied by weight-related health conditions such as high blood pressure or type 2 diabetes. They are not appropriate for everyone, and a proper medical evaluation is necessary to determine suitability, including a review of medical history, current medications, and overall health.
GLP-1 treatment is also considered as part of a broader approach to weight management rather than in isolation. As an endocrinologist, Dr Vikram considers factors such as metabolic health, existing medical conditions, current medications and the individual’s overall health profile when assessing whether GLP-1 based treatment may be appropriate.
This is also important when setting realistic expectations around weight loss and considering how medication, nutrition, physical activity and longer-term management may work together.
What Happens After Stopping Treatment?
Weight regain can occur after GLP-1 medication is stopped as its effects on appetite and fullness diminish. Clinical studies following patients after semaglutide withdrawal have also shown that some of the weight lost during treatment may subsequently be regained.
Does this mean GLP-1 medication needs to be taken indefinitely? Not necessarily for everyone. The appropriate duration of treatment depends on the individual, their response to medication, underlying health conditions and longer-term weight management needs.
This is why GLP-1 treatment is better considered as part of a longer-term strategy that may include nutrition, physical activity, behavioural changes and management of underlying metabolic or hormonal conditions, rather than simply as a short-term way to reach a target weight.
Are All GLP-1 Based Medications the Same?
No. Medications commonly discussed in relation to GLP-1 do not all work in exactly the same way and are not necessarily used for the same purpose.
Semaglutide and liraglutide are both GLP-1 receptor agonists that have been studied for weight management. Semaglutide is used in medications such as Ozempic and Wegovy, while liraglutide is used in Saxenda and Victoza. However, medications within the same GLP-1 class are not necessarily interchangeable, as their approved uses, dosing and treatment indications may differ.
Tirzepatide works differently by acting on both GIP and GLP-1 receptors rather than GLP-1 alone.
Dulaglutide is also a GLP-1 receptor agonist but is primarily used in the management of type 2 diabetes, with weight loss sometimes observed during treatment.
Rather than comparing these medications based only on which produces the greatest average weight loss, the more relevant question is which treatment, if any, is appropriate for the individual’s health needs and clinical circumstances.
Struggling to Lose Weight?
GLP-1 based medications have expanded the options available for medical weight management, but they are not interchangeable or appropriate for everyone. Understanding what may be contributing to weight gain, setting realistic expectations and considering how treatment fits into longer-term metabolic health are just as important as the medication itself.
If you are considering medical weight management, you may speak with Dr Vikram, Endocrinologist at Harmony Thyroid, Endocrinology and Diabetes Centre, about whether further assessment or treatment may be appropriate for you.
If you’d like to find out more about your options, book an appointment or a teleconsult with Dr Vikram to speak with our endocrinologist and take the first step towards a weight management plan that’s built around you.
References
- Wilding JPH, Batterham RL, Calanna S, et al. “Once-Weekly Semaglutide in Adults with Overweight or Obesity.” New England Journal of Medicine, 2021. https://www.nejm.org/doi/full/10.1056/NEJMoa2032183
- Garvey WT, Batterham RL, Bhatta M, et al. “Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial.” Nature Medicine, 2022. https://www.nature.com/articles/s41591-022-02026-4
- Wilding JPH, et al. “Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9542252/
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. “Tirzepatide Once Weekly for the Treatment of Obesity.” New England Journal of Medicine (SURMOUNT-1 trial). https://pubmed.ncbi.nlm.nih.gov/35658024/
- Wadden TA, Chao AM, Machineni S, et al. “Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial.” Nature Medicine, 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10667099/
- “Tirzepatide vs semaglutide and liraglutide for weight loss in patients with overweight or obesity without diabetes: A short-term cost-effectiveness analysis in the United States.” Journal of Managed Care & Specialty Pharmacy, 2025. (Cites SCALE trial data for liraglutide.) https://www.jmcp.org/doi/10.18553/jmcp.2025.31.5.441
- “Tirzepatide Tops Semaglutide for Weight Loss: SURMOUNT-5.” TCTMD, 2025. (References dulaglutide/Trulicity weight loss data.) https://www.tctmd.com/news/tirzepatide-tops-semaglutide-weight-loss-surmount-5