Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
Semaglutide has quickly become one of the most talked-about weight loss medications in the world, and for good reason. Originally developed to manage type 2 diabetes, it’s now helping people shed serious kilos and transform their health. But just how successful is it when used for weight loss?
Research shows semaglutide can lead to an average weight loss of 10–15% of body weight, and even up to 20% for some people. But that’s not the full story. The success rate depends on several personal factors, from your starting weight and dose to your lifestyle and consistency with injections.
Success with semaglutide isn’t just about the number on the scales; it’s about achieving sustainable, healthy results. In clinical terms, success is often defined as losing at least 5% of your starting body weight within a few months of consistent treatment. For example, if someone starts at 100 kg, losing 5 kg or more is already considered a meaningful success, as it can improve blood sugar control, blood pressure, and cholesterol levels.
However, many participants in semaglutide trials go far beyond that. According to the STEP clinical trials, over 86% of people using semaglutide achieved more than 5% weight loss, compared to just 31% of those on a placebo.
Let’s get into the data. Several large-scale studies have explored semaglutide’s weight loss success rate:
STEP 1 Trial: Participants taking 2.4 mg of semaglutide weekly lost an average of 14.9% of their body weight after 68 weeks.
STEP 3 Trial: Combined with intensive behavioural therapy, the average weight loss reached 16%.
Real-world data: In everyday use outside clinical trials, patients still lost around 13–20% of their body weight over 12 months.
These studies confirm semaglutide’s success rate is one of the highest among all approved weight loss medications. But it’s not a ‘magic jab’. How well it works depends on how it’s used.
While semaglutide is powerful, results can vary a lot from person to person. Here are the biggest factors that can influence your success:
People with a higher starting BMI tend to experience greater absolute weight loss (in kilograms), although the percentage of body weight lost often remains similar. For example, someone with obesity (BMI 35+) may lose more total kilos than someone slightly overweight, even if both drop 15% of their body weight.
Semaglutide works best when the dose is gradually increased over several weeks. Rushing this process can cause digestive side effects like nausea and vomiting, while staying too long on a low dose might limit your results. Clinical data shows that most people achieve optimal weight loss at the 2.4 mg weekly dose.
Skipping doses or irregular injections can reduce effectiveness. Since semaglutide builds up in your system over time, consistency is key to maintaining appetite suppression and stable blood sugar levels. Missing multiple doses can cause your progress to stall, or even reverse.
No medication can fully override diet. Semaglutide helps reduce appetite, but it’s most effective when paired with mindful eating and balanced nutrition. Studies show that patients who adopt proper lifestyle modification see significantly better long-term outcomes than those who rely on the medication alone.
For practical food guidance, read What To Eat While Taking Weight Loss Injections to learn how to make your meals work with,not against, your treatment.
Exercise helps preserve lean muscle and boosts metabolism during weight loss. Even moderate activity, like brisk walking, cycling, or strength training three times a week, can enhance fat loss while keeping your energy levels stable.
Conditions like insulin resistance, PCOS, thyroid disorders, or sleep apnoea can make weight loss slower. These issues can influence how your body responds to semaglutide and how efficiently it burns energy. Working with a healthcare provider to manage these conditions can make a big difference.
Some prescription drugs, like antidepressants, corticosteroids, or beta-blockers, may affect appetite or metabolism, potentially reducing semaglutide’s effectiveness. Always tell your doctor about any medications or supplements you’re taking before starting treatment.
Success on semaglutide isn’t just about the medication. Your metabolism matters too. Read Does Semaglutide Increase Metabolism? to see how metabolic changes can impact your weight loss results.
Semaglutide can be a game-changer, but maximising your results still requires a holistic approach. Here’s how to set yourself up for success:
Your doctor knows how to tailor your dose safely and gradually. Don’t increase doses on your own. It can worsen side effects and doesn’t speed up results.
Focus on nutrient-dense foods: lean proteins, veggies, whole grains, and good fats. Research suggests that people who make dietary changes alongside semaglutide can lose more weight than those who don’t.
Aim for at least 150 minutes of moderate exercise a week. You don’t have to hit the gym. Swimming, dancing, or weekend hikes all count.
Semaglutide doesn’t just change your weight; it can improve blood sugar, blood pressure, and waist circumference. Celebrate all your wins, not just the ones on the scales.
Chronic stress raises cortisol, which can stall fat loss. Getting 7–9 hours of sleep helps regulate hunger hormones like ghrelin and leptin, supporting semaglutide’s effects.
Regular follow-ups let your provider adjust your dose, manage side effects, and keep you motivated through plateaus. Accountability matters more than you’d think.
Consistency and lifestyle habits play a big role in semaglutide’s effectiveness. Read Weight Loss Plateau Solutions to discover strategies to overcome plateaus and enhance your progress.
So, what’s the real success rate of semaglutide for weight loss? Most users achieve meaningful weight loss (5% or more of body weight).
Keep in mind that semaglutide works best when it’s part of a bigger lifestyle change. Combine consistent dosing, mindful eating, and active living, and you’ll give yourself the best shot at long-term success.
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.