Not Losing Weight on Mounjaro or Ozempic? What to Check First

If you've just started Mounjaro, Zepbound, Ozempic or Wegovy, a slow start is normal: the first months are spent building the dose up gradually, and most of the weight comes off over months, not weeks. If you've been on treatment for a while and lost very little, check four things: what you drink, how often you pick at food, how much protein you eat, and what other medicines you take. In the UK, 5% of your starting weight after 6 months is the yardstick for a conversation with your prescriber.

How much weight loss is normal

The best benchmark is the big trials, not social media, which shows the fastest losers:

Trial	Medicine	Length	Average weight loss	Lost at least 5%
STEP 1	Semaglutide (Wegovy)	68 weeks	14.9%, against 2.4% on placebo	86% of people
SURMOUNT-1	Tirzepatide (Zepbound)	72 weeks	15.0–20.9%, depending on dose, against 3.1% on placebo	85–91% of people

Those averages hide a wide range. In STEP 1, half the people on semaglutide lost 15% or more, but about 1 in 7 didn't reach 5%. In SURMOUNT-1, 9 to 15% of people on tirzepatide fell short of 5%, depending on the dose. Both figures count everyone, including people who stopped treatment. Responding less well is real, and it isn't a personal failing.

Why the first months can be slow

The dose is built up gradually. The Wegovy label raises the dose over 16 weeks, and the main tirzepatide trial took 20. The Zepbound label says its starting dose is for starting treatment and isn't approved as a maintenance dose. The early doses are there to let your stomach adjust, so modest early loss is expected. When and how your dose goes up is your prescriber's call.

Most of the loss comes over the first six months. The 2025 joint advisory from four US obesity and nutrition societies describes weight loss as fastest in the first six months, slowing after that and levelling off at around 18 months. Judging the medication by the first few weigh-ins is too early.

The scale moves around. Weigh yourself once a week, on the same morning, and compare month with month rather than day with day.

If you were losing steadily and it has stopped, that's a different problem. See weight loss plateaus.

Eating habits that slow it down

These medications turn down your appetite, but some habits get around that:

• Calories in drinks. Sugary drinks, juice, large milky coffees and alcohol add calories without feeling like a meal. The advisory recommends avoiding sugar-sweetened drinks altogether. See alcohol on a GLP-1.
• Picking through the day. A smaller appetite makes it easy to graze on biscuits, crisps or bread without feeling you've eaten a meal. Regular small meals make it much easier to see what you're actually eating.
• Comfort food on queasy days. The advisory notes that nausea can trigger cravings for sugary and refined-carb comfort food. Managing nausea has protein-first options that still go down easily.
• Guessing instead of checking. The advisory recommends checking what you eat with food logs or photos. A few days of photos can show where the calories are coming from.

Protein and strength training won't make the scale move faster, but they help decide what you lose. More of it comes from fat and less from muscle, which matters for how you look and feel at the end. See muscle loss on a GLP-1 and exercise on a GLP-1.

Medicines that can work against you

Some common medicines are linked to weight gain. A review of 257 trials found it with:

• the antidepressants amitriptyline and mirtazapine
• the antipsychotics olanzapine, quetiapine and risperidone
• gabapentin, used for nerve pain and epilepsy

They can make weight loss harder. Never stop or change one yourself. Bring a list of your medicines to your next appointment and ask whether any alternatives make sense for you.

When to talk to your prescriber

The UK has a clear yardstick. NICE says to consider stopping semaglutide if you've lost less than 5% of your starting weight after 6 months of treatment. For tirzepatide, it says to decide whether to continue if you've lost less than 5% after 6 months on the highest dose you can tolerate. Five percent of 100 kg is 5 kg; of 220 lb, 11 lb.

Talk to your prescriber if:

• you're near that point and well short of 5%
• side effects are stopping you from eating properly
• you take any of the medicines above
• you're thinking of changing your dose, which should only happen with their advice

What to do this week

1. Weigh once a week, same morning, and keep a simple note.
2. Photograph everything you eat and drink for three days.
3. Swap drinks with calories for water, tea, or coffee with a splash of milk.
4. Eat three regular meals with protein first. The protein calculator gives your daily target.
5. Write down your other medicines for your next appointment.

A few simple, protein-first meals to build around:

• Egg White Veggie Frittata: 24 g protein for 220 kcal
• Chicken and White Bean Soup: 30 g protein for 235 kcal
• High-Protein Greek Yogurt Bowl: 26 g protein, no cooking
• Lemon-Herb Baked Salmon with Greens: 29 g protein

For how much to eat overall, see how much to eat on a GLP-1.

General nutrition information, not medical advice. Decisions about your dose or other medicines belong with your prescriber.