How much weight can I lose on Mounjaro?

Clinical trials by Ely & Lilly say that patients can lose on average 26.6% of their body weight by taking tirzepatide, also sold under the brand name Mounjaro. That is impressive, but how reliable is this result? And is it likely that the typical patient would lose this amount of weight? We wanted to find out so we did our own research and went over more than 150 patients and their results to compare their anecdotal outcomes to the results of the Surmount-3 clinical trial, referred to in the patient leaflet and used as a standard claim when discussing the medication with patients. To be consistent We have used kg as the metric for weight in the text and analysis; however, some patients have expressed weight in lb and when that was the case, we have kept the quote as it is.

The Surmount-3 study, a clinical trial by Eli Lilly

Here is a summary of how the Surmount-3 clinical trial was conducted:

1. First, about 800 adults who weighed around 109.5 kg joined a 12-week program of diet, exercise, and counselling to try to lose at least 5 % of their body weight.
2. Those who hit that 5 % loss (about 5.5 kg on average) were split into two groups by chance: one got weekly injections of tirzepatide and the other got a placebo, and neither the participants nor the researchers knew who was in which group.
3. For the next 72 weeks, everyone kept up with diet and exercise advice while taking their assigned injection, and the study tracked how much weight patients lost and how many maintained at least a 5 % drop.
4. Researchers also looked at how many participants lost 20 % or more of their starting weight (for example, about 22 kg for someone weighing 110 kg) and whether they kept off the weight they lost during the first 12 weeks.
5. In total, each person was in the study for 84 weeks, letting scientists see both short-term and long-term effects on weight and safety.

Surmount-3 Results:

• Average total weight loss: 26.6% of body weight (~29kg) over 84 weeks.
• Lifestyle phase (12 weeks): ~6.9% weight loss.
• Tirzepatide phase (72 weeks): Additional ~21.1% weight loss.
• The placebo group regained much of the lost weight.
• More than 85% of tirzepatide users maintained more than 80% of their total weight loss.
• Side effects: Mostly mild/moderate nausea, diarrhoea, and vomiting.

We have used this information when analysing the anecdotal data from more than 150 patients. The data is a collection of patient stories, written by them, where they summarise their experience and share data such as how they felt, side effects experienced and how much weight they lost. Let’s start with some comments from the patients:

Comments from patients

"I am an African American female, 58 years old, 5’8" tall, weighed an unbelievable 270 lbs on 12/30/22. I asked my doctor if I could take this medication, and now here we are, 8 weeks later. I currently weigh 244.6 lbs. I lost 16 lbs in the first 3 weeks."

"315-pound man, 64... went on Mounjaro lowest dose 2.5. Have lost 40 pounds (!) in two months, eat anything and everything just way less and no desire to snack between. A miracle, has changed my life mentally and physically."

"I have been on the 15 mg/0.5 mL for the last four months and on Mounjaro for a total of ten months starting with the 2.5 mg dosage. I have lost a total of 115 lbs. I have gone from being 455 lbs to my current weight of 340 lbs."

"I started using Mounjaro in July 2022 and weighed 206 lbs. It is now March 2023 and I now weigh 130 lbs. The Mounjaro eliminated the desire to eat."

"I’m 58 years old and weighed 176 lbs. I started on Mounjaro at the end of last August. I’m on the 5 mg and have currently lost 56 lbs, now weighing 120 lbs."

"This medication was a life changer for me. I’ve been on the medication for 6 months and have lost a total of 56 pounds. I’m now at 133 pounds."

"In the last 18 months, I have lost 130 pounds! My current weight is 170 pounds, which surpassed my goal weight. My blood pressure is within normal range, and my type two diabetes is controlled!"

"I have now been taking Mounjaro for 8 months. I have now lost 65 lbs. I started at a very athletic 385, and now I am 320."

"I’ve been on Mounjaro for 4 months and have lost 60 lbs. Best stuff out there. I tried Ozempic, but it didn't compare to the results of Mounjaro."

"I started Mounjaro at 2.5 mg, 8 months later I am at the 7.5 mg dose. I went from 210 to 150 lbs. This is a life-changer for me."

"I started on Mounjaro, paying my own way, on March 3rd of this year. 43 weeks in, with no side effects of any type, I've lost 103 lbs. I'm eating in a far less and healthier manner as I am able."

"Started last January at 268 pounds, 5 ft 7 in, morbidly obese. One year later, I'm down to 159 pounds and have never been healthier. The only side effect I've had from this medication is really bad constipation."

"I have lost 90 lbs on Mounjaro over the last 14 months. Mounjaro has truly changed my life. I was giving up hope and falling into depression because nothing worked."

"I lost 45 lbs in about 9 months. I'm barely eating anything, and when I tried stopping, the appetite comes back ferociously. I am now considered anorexic and having the nutritionist help me taper off the med."

"I’ve been on Mounjaro for 12 weeks and I've lost 25kg (55lbs). No major side effects, but I do have dry mouth (very, very dry mouth and throat) and dry lips. The weight has drastically come off."

So from our research, how much did they lose?

The outcomes we analysed show variability but generally align with the Surmount-3 trials. In the anecdotal reports, short-term (4–8 weeks) weight losses ranged from approximately 4.5 to 18 kg with minimal lifestyle changes beyond Mounjaro alone. For example, a 143 kg individual lost 18 kg in two months on tirzepatide without altering diet or exercise, and another patient shed 5 kg in just one week by combining a ketogenic-style diet with tirzepatide’s appetite suppression. Over three to six months, many users reported 13.6 to 36 kg of weight loss: one person went from 101 to 92 kg, losing 8.8 kg in 30 days on low-dose Mounjaro plus modest dietary changes, and another dropped from 166 to 127 kg, a 39 kg loss in about 10 months, which qualified him for knee replacement surgery. Longer-term follow-up (9–18 months) often exceeded 36 to 59 kg: one patient went from 136 to 77 kg over 18 months (59 kg total loss) and achieved normal blood pressure and controlled diabetes; another reported a 32 kg loss over 14 months and has maintained it.

Pharmacist comment

We discussed the findings with our superintendet pharmacist, Alessandro Grenci:

In the clinical trials, the subjects are more tightly controlled, both in terms of the selection criteria to partake and also in the instructions given to them regarding health and lifestyle. In the research we did we could see that factors like internal motivation or high weight at the beginning of the treatment can help accelerate the weight loss. In general, we can see that the clinical trials in sth Surmoun study are realistic but that there is variation on an individual level.

The full comparison

Conclusion

Overall, anecdotal reports of Mounjaro-associated weight loss broadly corroborate Surmount-3 findings, demonstrating that substantial (20–30 %) reductions in body weight are achievable. In practice, some patients may lose weight more rapidly (especially when combining Mounjaro with very low-calorie or ketogenic diets), while others mirror the trial’s average trajectory of \~ 26.6 % loss over roughly 18 months.

Assuming 26.6% weigthloss, here is a table outlining how much a typical patient could lose depeding on starting weight:

Sources:

drugs.com - reviews for mounjaro for obesity

Eli Lilly Surmount Trial

Written by Christian Jakobsson