When Ozempic (Semaglutide) Starts Suppressing Appetite
Semaglutide begins suppressing appetite within the first few days to weeks of treatment, with measurable reductions in energy intake and appetite ratings observed as early as week 20 of treatment in clinical trials, though patients typically report subjective appetite suppression much earlier during the dose titration phase. 1
Immediate Appetite Effects During Titration
Appetite suppression begins during the initial titration phase, which starts at 0.25 mg weekly for the first 4 weeks, though the full appetite-suppressing effect increases progressively as the dose escalates toward the maintenance dose of 2.4 mg weekly (reached after 16 weeks). 2
Clinical trial data demonstrates that by week 20 of treatment with semaglutide 2.4 mg, patients experience a 35% reduction in ad libitum energy intake (1736 versus 2676 kJ compared to placebo), with significant reductions in hunger and prospective food consumption, and increased fullness and satiety. 1
Patients report reduced hunger, increased fullness and satiety, and better control of eating with fewer food cravings compared to placebo, with these effects becoming more pronounced as the dose increases during titration. 1
Mechanism and Timing of Appetite Suppression
Semaglutide suppresses appetite through multiple central nervous system pathways, including activation of GLP-1 receptors in the hypothalamus (particularly anorexigenic POMC neurons), brainstem signaling, and vagal nerve activation, which generate powerful satiety signals that begin working as soon as therapeutic drug levels are achieved. 2
The medication has a half-life of 7 days and reaches steady-state concentrations in 4-5 weeks, meaning that the full pharmacological effect on appetite suppression continues to build during the first month of treatment. 3
Delayed gastric emptying contributes to prolonged feelings of fullness, though this effect may show some tachyphylaxis (tolerance) with continuous exposure, while the central appetite-suppressing effects remain robust throughout treatment. 2, 1
Clinical Timeline for Patients
Most patients notice subjective appetite reduction within 1-2 weeks of starting treatment, even at the initial 0.25 mg dose, though individual responses vary considerably. 2
The appetite-suppressing effect intensifies progressively during dose escalation (0.25 mg → 0.5 mg → 1.0 mg → 1.7 mg → 2.4 mg weekly), with each dose increase typically producing additional appetite suppression over the subsequent 4 weeks. 2
Maximum appetite suppression is typically achieved after reaching the maintenance dose of 2.4 mg weekly and allowing 4-5 weeks for steady-state drug levels, which corresponds to approximately 20 weeks from treatment initiation. 3, 1
Practical Considerations
Slow titration is essential not only to minimize gastrointestinal side effects but also to allow patients to adapt to the appetite changes, as the sudden reduction in hunger can be disconcerting for some patients. 2
Nausea occurs in 18-40% of patients and is most common during dose escalation, which can be mistaken for appetite suppression but represents a distinct side effect that typically improves over time. 2
Dietary modifications during the early weeks—such as reducing meal size, eating slowly, and limiting alcohol and carbonated beverages—can help patients adjust to the appetite-suppressing effects while minimizing gastrointestinal discomfort. 2
Important Caveats
The appetite-suppressing effect is dose-dependent, meaning patients who remain at lower doses (such as 0.5 mg or 1.0 mg weekly for diabetes management) will experience less appetite suppression than those reaching the 2.4 mg obesity-treatment dose. 4, 1
If treatment is discontinued, appetite suppression reverses relatively quickly, with patients typically experiencing return of normal hunger within 2-4 weeks as drug levels decline, contributing to the significant weight regain observed after stopping treatment. 2
Individual variation is substantial—some patients report dramatic appetite suppression within days, while others experience more gradual effects over several weeks, and a small percentage may not experience significant appetite changes even at maximum doses. 2