How much weight can you lose on Ozempic is the first thing most people ask before starting the pen. The honest answer is not a fixed number. The average from the studies is good, but the scale alone hides the part that matters most: how much of what you lose is fat and how much is muscle.
By Lucas, nutritionist. Updated July 24, 2026. Educational nutrition content, based on clinical studies.
This guide shows the real pace of loss, why the first weeks fool you, and how to make sure the number going down is fat, not lean mass.
Disclaimer: this is educational nutrition content. It does not replace your doctor or dietitian, and using the medication requires medical supervision. Nothing here covers dose, prescription, or which pen to take.
So, how much weight can you lose on Ozempic each week?
Across the studies, weight loss on the pen averages roughly 0.3 to 0.5 kg per week over the full course, with a faster drop in the first month.
The benchmark number comes from the STEP 1 trial with semaglutide, the active ingredient in Ozempic and Wegovy. Participants lost an average of 14.9% of their body weight over 68 weeks.
Run the math with an example. A person weighing 90 kg who loses 15% drops about 13.5 kg. Spread over more than a year, that is less than half a kilo per week on average.
The start looks stronger. In the first weeks the scale falls fast because part of what leaves is water, not fat. Then the pace slows, and that is when many people think the pen stopped working.
Quick answer (the study average):
- First month: usually the fastest, much of it water.
- Overall average: around 0.3 to 0.5 kg per week across the course.
- Healthy benchmark pace: 0.5 to 1 kg per week.
Ozempic vs Mounjaro: how much each pen takes off
Tirzepatide, the drug in Mounjaro, tends to reach higher totals than semaglutide, in Ozempic, in the obesity studies.
They are different molecules. Semaglutide mimics one hormone, GLP-1. Tirzepatide acts on two, GLP-1 and GIP. That shows up in the average results.
| Pen | Drug | Average loss in the study | Time |
|---|---|---|---|
| Ozempic and Wegovy | Semaglutide | about 15% of body weight | 68 weeks |
| Mounjaro | Tirzepatide | 16% to 22.5% of body weight | 72 weeks |
The figures come from the STEP 1 and SURMOUNT-1 trials. They are averages of large groups, not a promise. Your result depends on starting weight, time on the drug, food, and how much you move. Compare the molecules in our guide on semaglutide vs tirzepatide.
ContaCal
Track your protein while the weight comes off
When appetite drops, it is easy to eat too little and lose muscle along with fat. Snap your meal and see calories and protein instantly.
Or see the ContaCal calorie tracking app.
Why the scale fools you in the first weeks
Much of what disappears fast at the start is water and glycogen, the muscle's energy store, not fat.
When you eat far less, the body spends its stored glycogen. Every gram of glycogen holds about three grams of water. That store leaves first, and the scale reacts hard.
So the first month looks like a miracle and the second looks like a stall. It is not the pen failing. It is water returning to normal while fat, which leaves more slowly, takes over. See what to expect at 3, 6 and 12 months in Ozempic before and after.
The kilo you do not want to lose: muscle
Between 25% and 40% of the weight lost on the pen can be lean mass if you do not protect muscle with protein and strength work.
The pen cuts hunger. The silent side effect is eating too little protein. Without enough protein, the body pulls amino acids from your own muscle to keep going, more so when the loss is fast.
Losing muscle costs you. It supports strength, skin firmness, and the energy you burn at rest. Less muscle today makes the body more likely to regain weight tomorrow.
Warning: losing weight very fast on almost no food is not a win. If the day ends well below your minimum and without protein, the body burns muscle along with fat. Eat little, but eat right.
How much protein protects your result
Aim for 1.2 to 2 grams of protein per kilo of body weight a day to hold on to muscle while you lose weight.
A person weighing 70 kg needs somewhere between 84 and 140 grams of protein a day. It sounds like a lot when you have no appetite, but you can split it and make it easy.
Hit protein in your first bites, while appetite still exists. Aiming for 30 to 40 grams per meal is easier than facing it all at dinner.
Practical sources: a 150 gram chicken breast has about 45 grams of protein. Two eggs add 12. A cup of plain yogurt, 8 to 10. Beans and rice help close the gap. For the full plate, see what to eat on the pen.
What weekly pace is healthy
Losing 0.5 to 1 kg per week is usually the sweet spot between results and muscle preservation.
The pen can push the pace past that, especially early. Faster is not better. The quicker the drop, the larger the share that comes from lean mass if protein and strength are not in place.
Two things protect the result: hitting protein every day and lifting weights two or three times a week. Together they tell the body to hold muscle and release fat. If the scale has stalled for weeks, there is a reason and a fix in our guide on the semaglutide plateau.
And when the pen stops?
Without the eating habits built during treatment, part of the weight tends to come back once the medication stops.
The STEP 1 trial extension showed many participants regained much of the weight after stopping. What holds the result is not the pen itself, it is the routine of eating right that stayed.
That is why preserved muscle and a record of what worked matter so much. They are the bridge between treatment and maintenance.
