Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
Semaglutide has become a widely discussed option in the world of weight management, with many turning to it for its ability to curb appetite and support long-term weight loss. Originally developed to manage type 2 diabetes, semaglutide is now also prescribed under brand names like Ozempic for weight-related concerns. Clinical studies have shown that people using semaglutide can lose up to 15% of their body weight, largely due to its appetite-suppressing effects.
But how quickly does this effect kick in? If you’ve just started semaglutide or are considering it, you might be wondering when you’ll begin to notice a reduced desire to eat. In this article, we’ll explore how semaglutide works, when it typically starts to suppress appetite, and what factors may influence its effectiveness.
Semaglutide is part of a class of medications called GLP-1 receptor agonists. It mimics a naturally occurring hormone called glucagon-like peptide-1 (GLP-1), which helps regulate blood sugar, slows gastric emptying, and signals fullness to the brain. As a result, semaglutide not only helps reduce appetite but also makes it easier to maintain a calorie deficit without constantly feeling hungry.
Clinical studies back this up. In the STEP 1 trial, participants taking semaglutide lost an average of 14.9% of their body weight over 68 weeks, compared to 2.4% in the placebo group. Much of this weight loss is attributed to decreased appetite and reduced food intake. By helping people feel full sooner and for longer, semaglutide can play a key role in long-term weight management, especially when paired with a nutritious diet and regular movement.
Want to learn more about how it works? Read our article What Is Semaglutide And How Does It Work for Weight Loss?
For most people, semaglutide begins to reduce appetite within the first week or two of starting treatment, although the full appetite-suppressing effects may take several weeks to become noticeable. This gradual onset is largely due to the way semaglutide is introduced—starting with a low dose and increasing it over time to minimise side effects such as nausea or gastrointestinal discomfort.
GLP-1 receptor agonists like semaglutide begin to alter eating behaviour early in the treatment course, even before significant weight loss occurs. Many participants in the STEP trials reported feeling less hungry and more satisfied with smaller portions by the time they reached the 1 mg weekly dose.
That said, how quickly you notice reduced appetite can vary based on your dose, metabolism, and lifestyle habits. For some, results may be more gradual, while others experience appetite changes within days of their first injection.
While semaglutide isn't a quick fix, the way you schedule your doses can support a smoother and more effective experience. Most treatment plans start at 0.25 mg once a week, then gradually increase to 1 mg or more over several weeks. This stepwise approach helps your body adjust to the medication and reduces the likelihood of side effects like nausea, vomiting, or bloating.
The slow titration strategy, starting at a lower dose and gradually increasing, helps minimise common side effects like nausea, especially in the early stages of GLP-1 RA treatment. This not only improves tolerability but also supports better long-term adherence. People who follow their dose schedule consistently are more likely to experience early appetite suppression and achieve more sustainable weight loss over time.
To optimise your results, it’s important to:
Stick to the prescribed dosing schedule
Take your injections on the same day each week
Pair your treatment with a high-protein, fibre-rich diet and daily movement
These small, consistent habits can help semaglutide work more effectively and reduce your appetite sooner rather than later.
While many people start noticing appetite suppression within a few weeks, several individual factors can influence how quickly semaglutide takes effect. These include:
Starting dose level: Semaglutide is usually introduced at a low dose and gradually increased. The appetite-suppressing effects tend to become more noticeable at higher doses, typically around 0.5 mg to 1 mg or more.
Metabolism speed: A faster or slower metabolism can impact how your body processes semaglutide. Some people may absorb and respond to the medication more quickly than others.
Diet quality: A balanced diet rich in protein and fibre can support semaglutide’s effects, while high-sugar or high-fat foods may blunt appetite control and make it harder to notice changes.
Physical activity: Regular movement improves insulin sensitivity by lowering insulin levels and supports better overall metabolic health, which can complement semaglutide’s action and help you see results sooner.
Sleep patterns: Poor or irregular sleep can affect appetite hormones like ghrelin and leptin, potentially reducing semaglutide’s effectiveness in curbing hunger.
Stress levels: Chronic stress can lead to emotional eating and hormonal imbalances, which can make it harder to notice appetite changes, even when using semaglutide.
Semaglutide can be a powerful tool for appetite control, but its effectiveness can be enhanced by the choices you make each day. These practical tips can help support its action and improve your overall results:
Eat high-protein and high-fibre meals: Protein and fibre help you feel fuller for longer and work in sync with semaglutide’s appetite-suppressing effect. High-protein diets can reduce cravings and late-night snacking, while fibre slows digestion and promotes satiety.
Avoid high-sugar and greasy foods: These foods can spike blood sugar and increase hunger soon after eating. Over time, they may also blunt the benefits of semaglutide by promoting insulin resistance and disrupting appetite regulation.
Stay hydrated: Drinking enough water supports digestion, energy levels, and metabolism. Mild dehydration can sometimes be mistaken for hunger, making it harder to track whether semaglutide is working as expected.
Move your body daily: You don’t need intense workouts. Even a brisk walk, stretching session, or light cardio can enhance how your body responds to semaglutide. Regular physical activity also helps regulate appetite-related hormones and improves mood and energy.
Stick to your dosing plan: Semaglutide works best when taken consistently. Following your schedule, especially during the dose escalation phase, ensures your body adjusts properly and maintains the appetite-suppressing effect over time.
Semaglutide can be a powerful ally in managing appetite and supporting weight loss, but its effects are not instant, and they vary from person to person. Understanding how the medication works, what influences its timing, and how to support it through healthy habits can make a meaningful difference. By staying consistent with your dosing schedule, choosing nourishing foods, staying active, and managing stress and sleep, you’ll give semaglutide the best chance to work effectively. As always, speak with your healthcare provider before making any changes to your treatment plan to ensure it’s right for your health needs and goals.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.