Not losing weight on semaglutide or tirzepatide: what to check in your eating and records
If your weight is not coming down on semaglutide or tirzepatide, first check how much you actually eat and drink: the medicine reduces appetite, but calories from drinks, snacks and weekends do not go away. Then compare your expectations with the research: results varied widely from person to person. Only your doctor decides on the dose, schedule, switching or stopping the medicine, and the question "why am I not losing weight" is one to ask them too.
What the studies showed and why it is not a forecast
In Russia, semaglutide is registered under names including Semavic and Velgia, and tirzepatide under names including Tirzetta and Sejaro. All four are listed in the Russian State Register of Medicines as of October 12, 2026, and are prescription-only. How the substances themselves differ is covered in the article on Ozempic, Mounjaro and their Russian versions. The figures below come from studies of the original medicines.
| Study | Participants | Mean weight change | Did not lose at least 5% |
|---|---|---|---|
| STEP 1, semaglutide, 68 weeks | 1,961 adults with obesity or overweight, without diabetes | −14.9% vs −2.4% with placebo | 13.6% of participants with a week-68 measurement |
| SURMOUNT-1, tirzepatide, 72 weeks | 2,539 adults with obesity or overweight, without diabetes | −15.0% to −20.9% across three groups on different doses vs −3.1% with placebo | 9% to 15%, depending on the group |
| STEP 2, semaglutide, 68 weeks | 1,210 adults with overweight or obesity and type 2 diabetes | −9.6% vs −3.4% with placebo | — |
| SURMOUNT-2, tirzepatide, 72 weeks | 938 adults with overweight or obesity and type 2 diabetes | −12.8% and −14.7% in two groups vs −3.2% with placebo | — |
These are group averages, with a wide spread around them. In STEP 1, one in seven participants measured at the end did not reach even a 5% loss, while some lost more than 20%.
In the studies that enrolled people with type 2 diabetes, average weight loss was smaller than in the studies without diabetes.
Participants in STEP 1 and SURMOUNT-1 also received more than the medicine. According to the full texts, all participants, including the placebo groups, met regularly with a counsellor who helped them keep a deficit of about 500 kcal a day and stay active for at least 150 minutes a week. The figures in the table reflect the medicine together with this dietary support.
The studies cannot tell you what result to expect. That depends on your diagnosis, other conditions, other medicines and the prescribed regimen, and it is something to discuss with the doctor managing your treatment.
Weight can stall on medication too
In STEP 1, average weight fell from the first check at week 4 and reached its lowest point by week 60. In SURMOUNT-1, by the end of 72 weeks weight had plateaued in one group and nearly plateaued in the other two. So a stall after many months of treatment was part of the usual curve in these studies, not a sign that the medicine had stopped working.
But what the curve should look like for a particular person, and when a stall calls for any change, is for the doctor to decide. Why weight stalls with any weight loss method is covered in the articles on plateaus and metabolic adaptation.
How much you actually eat
The feeling of "I hardly eat anything" can differ from the actual numbers, and the medicine does not change that. In a study by Lichtman et al., 10 people who said they did not lose weight while eating under 1,200 kcal a day were observed for two weeks with precise measurement of their energy expenditure. Their metabolism was within 5% of the predicted value, and they ate on average 47% more than they recorded. No signs of psychiatric disorders were found: the issue was in estimating what they ate.
Things that easily stay out of the record:
- Drinks. Juice, sweetened coffee, smoothies and alcohol provide calories but do not feel like food, so they are easy to leave out. Their calories are covered in the articles on coffee shop drinks, smoothies and alcohol.
- Snacks. If you only manage half a plate at lunch, small snacks may appear between meals: a biscuit, a piece of cheese, a handful of nuts. You barely notice them one by one, but over a day they add up to hundreds of kilocalories.
- Dense food in small portions. Nuts, cheese, oil and chocolate take up little space and fit in even with a small appetite. They pack many calories into a small volume, so an error of a few grams by eye shows up in the diary. How to estimate such portions is covered in the article on estimating portion weight without a scale.
- Weekends. Guests, a restaurant, a trip: two such days can cancel out a working week's deficit, yet look "about normal" in the diary.
To check, record everything for a week, including drinks, cooking oil and weekends, not just main meals. Weigh what you can and photograph the rest. How to read your own numbers afterwards is covered in the article on a week in your food diary. These records also help at your appointment: it is easier for a doctor to work things out when they can see what and how much you eat. If detailed tracking makes you anxious or reminds you of past difficulties with food, tell your doctor: the check can be done differently.
Protein, muscle and a scale that does not show everything
A scale adds fat, muscle and water into one number. Weight can stay the same while your waist shrinks, and it can fall through muscle loss rather than fat. So besides weighing yourself, measure your waist, and judge your weight by the weekly average: daily fluctuations are larger than a week's loss. How to read a stable scale with a shrinking waist is covered in the article on weight and waist.
With a reduced appetite, protein is the hardest thing to get enough of, and it determines whether you keep your muscle. How much protein you need on this treatment and how to eat it when you are not hungry is covered in a separate article on eating on weight loss medication.
When to see a doctor
Take the question "why am I not losing weight" to the doctor who prescribed the medicine rather than solving it yourself. Do not change the dose, skip or add injections, switch to another medicine or stop treatment without them. A week of food records and your weight and waist measurements will make the conversation concrete.
Also discuss with your doctor:
- Other medicines. Some medicines cause weight gain on their own; the groups are listed in the article on medicines that affect weight. Do not stop them on your own.
- Signs of illness. Weight rising along with swelling, constant feeling cold and fatigue. The doctor looks for the cause, which is sometimes the thyroid: more in the article on the thyroid and weight. Leg swelling with shortness of breath or chest pain is a reason to call an ambulance.
- Where the medicine was bought. The WHO has warned about falsified semaglutide: a fake may contain no active ingredient, in which case it has no effect on weight, or it may contain another substance, such as insulin. A pen bought anywhere other than a pharmacy with a prescription is a reason to tell your doctor.
Severe abdominal pain that does not go away, persistent vomiting and signs of dehydration are reasons to seek help immediately rather than waiting for a scheduled appointment. These signs are covered in more detail in the article on eating with nausea.
Frequently asked questions
- Why am I not losing weight on semaglutide?
- First check whether you are eating and drinking more than it seems: drinks, snacks and weekends easily stay out of the record. Response to the medicine also varies: in the STEP 1 study, one in seven participants measured at the end did not lose even 5%. Why this is happening in your case is something to work out with your doctor.
- Is it normal for weight to stall on the medication?
- In the studies, weight on semaglutide and tirzepatide plateaued after many months: in STEP 1 the average lowest point came at week 60. But how your curve should look and whether anything needs to change is for your doctor to decide.
- Can I increase the dose myself if my weight is stuck?
- No. Only a doctor decides on the dose, injection schedule, switching or stopping the medicine. Bring a week of food records and your weight and waist measurements to the appointment.
- Should I count calories on semaglutide?
- A week of complete records helps you check how much you actually eat. In the STEP 1 and SURMOUNT-1 studies, participants received dietary counselling with a deficit of about 500 kcal a day alongside the medicine. If tracking is hard for you, discuss your eating with your doctor.
- How is tirzepatide different from semaglutide?
- Semaglutide acts on receptors for the hormone GLP-1, while tirzepatide acts on receptors for two hormones, GLP-1 and GIP. In the head-to-head SURMOUNT-5 trial of 751 people, weight fell by an average of 20.2% on tirzepatide and 13.7% on semaglutide over 72 weeks. The choice of medicine is made by a doctor.
Read next
- Nutrition while on weight loss medication: how to maintain muscle mass — In published observations, lean tissue accounted for between one-quarter and forty percent of total weight lost.
- Weight loss plateau: why weight stalls and what to do about it — The weight has stayed at the same number for the third week in a row, even though the diet hasn't changed — and the first instinct is usually the same: to cut even more.
- Ozempic, Mounjaro and their Russian versions: how they differ — Behind Ozempic, Mounjaro and the Russian-made drugs there are only two active substances: semaglutide and tirzepatide.
This article is for general information. It is not medical advice, a diagnosis, or a prescription for treatment or a diet, and it does not replace a consultation with your doctor. If you have a health condition, are pregnant, take medication, or follow a diet prescribed to you, decisions about food belong with your doctor.
Figures from regulations, guidelines and studies are given as they stood when this article was prepared and may since have changed; check them against the primary sources. This article is not advertising, an offer, or individual advice, and neither the author nor the site owner is responsible for decisions taken on the basis of it.