Semaglutide starts working in the body shortly after the first dose, reaching peak concentration within 1 to 3 days. However, noticeable effects such as appetite reduction and weight loss typically take longer to appear. Most people begin to see changes in appetite within the first few weeks and start experiencing measurable weight loss around 4 to 12 weeks of treatment. Significant and more consistent weight loss usually happens over several months, with some individuals reaching substantial results after 20 weeks or more. Full effects on weight loss and blood sugar control may take up to 16-20 weeks or longer, depending on the dose and individual response. Steady state concentration of the drug is often reached after about 4-5 weeks of weekly use, which corresponds with more pronounced effects.