Tirzepatide for Weight Loss: What the Evidence Shows
What human and animal studies show about Tirzepatide for weight loss, how strong that evidence is, and what is still unproven.
- Strongest evidence
- Human RCT
- Human studies
- 990
- PubMed records, our ledger
- Animal studies
- 49
- PubMed records, our ledger
- Studies we summarised
- 16
- with an outcome for weight loss
Evidence for weight loss
Each row is an outcome related to weight loss from a published study, strongest design first. Animal and cell results are labelled and are not human results. User reports are not counted as evidence here.
| Outcome | Result | Study type | Source |
|---|---|---|---|
| Joint response plus weight loss | The combined joint-response and weight-reduction end point was met by 31.7% on ixekizumab plus tirzepatide vs 0.8% on ixekizumab alone. | Human RCTn = 271 | Arthritis & rheumatology 2026, PMID 41903163 |
| Weight change vs semaglutide | Tirzepatide reduced weight by 20.2% versus 13.7% with semaglutide at week 72. | Human controlled trialn = 751 | The New England journal of medicine 2025, PMID 40353578 |
| Waist circumference | Waist circumference fell by 18.4 cm with tirzepatide versus 13.0 cm with semaglutide. | Human controlled trialn = 751 | The New England journal of medicine 2025, PMID 40353578 |
| Fat mass and lean mass | At week 72, body weight, fat mass and lean mass changed by -21.3%, -33.9% and -10.9% with tirzepatide vs -5.3%, -8.2% and -2.6% with placebo. | Human RCTn = 160 | Diabetes, obesity & metabolism 2025, PMID 39996356 |
| Share of weight lost as fat | About 75% of weight lost was fat mass and 25% lean mass, for both tirzepatide and placebo. | Human RCTn = 160 | Diabetes, obesity & metabolism 2025, PMID 39996356 |
| Weight maintenance after lead-in | From week 36 to week 88, weight changed by -5.5% with continued tirzepatide versus 14.0% (regain) after switching to placebo. | Human RCTn = 670 | JAMA 2024, PMID 38078870 |
| Maintained 80% of weight loss | 89.5% of continuing participants kept at least 80% of lead-in weight loss, versus 16.6% on placebo. | Human RCTn = 670 | JAMA 2024, PMID 38078870 |
| Apnea-hypopnea index, trial 1 (no PAP) | Trial 1: AHI fell by 25.3 events per hour with tirzepatide versus 5.3 with placebo at week 52. | Human RCT | The New England journal of medicine 2024, PMID 38912654 |
| Apnea-hypopnea index, trial 2 (on PAP) | Trial 2: AHI fell by 29.3 events per hour with tirzepatide versus 5.5 with placebo at week 52. | Human RCT | The New England journal of medicine 2024, PMID 38912654 |
| Body weight change | Mean bodyweight change at week 72 was -12·8% (10 mg) and -14·7% (15 mg) versus -3·2% with placebo in people with type 2 diabetes. | Human RCTn = 938 | Lancet 2023, PMID 37385275 |
| Additional weight change after lifestyle intervention | After the lifestyle run-in, tirzepatide produced a further -18.4% weight change versus 2.5% with placebo. | Human RCTn = 579 | Nature medicine 2023, PMID 37840095 |
| Body weight change | Mean weight change at week 72 was -15.0% (5 mg), -19.5% (10 mg) and -20.9% (15 mg) with tirzepatide versus -3.1% with placebo. | Human RCTn = 2539 | The New England journal of medicine 2022, PMID 35658024 |
| Weight reduction of 20% or more | 50% (10 mg) and 57% (15 mg) of participants lost 20% or more of body weight, versus 3% with placebo. | Human RCTn = 2539 | The New England journal of medicine 2022, PMID 35658024 |
| Body weight | Body weight changed by -5.4, -7.5 and -8.8 kg with tirzepatide 5, 10 and 15 mg versus 1.6 kg with placebo. | Human RCTn = 475 | JAMA 2022, PMID 35133415 |
| Liver fat content | Absolute liver fat fell by 8·09% with pooled tirzepatide 10 and 15 mg versus 3·38% with insulin degludec at week 52. | Human RCTn = 296 | The lancet. Diabetes & endocrinology 2022, PMID 35468325 |
| Visceral and abdominal fat | Tirzepatide significantly reduced liver fat content and visceral and abdominal subcutaneous adipose tissue volumes versus insulin degludec. | Human RCTn = 296 | The lancet. Diabetes & endocrinology 2022, PMID 35468325 |
| Body weight | Tirzepatide caused a dose-dependent weight loss of 7·0 to 9·5 kg. | Human RCTn = 478 | Lancet 2021, PMID 34186022 |
| Body weight vs insulin degludec | Tirzepatide lowered bodyweight by 7·5 to 12·9 kg while insulin degludec increased it by 2·3 kg. | Human RCTn = 1437 | Lancet 2021, PMID 34370970 |
| Weight loss, tirzepatide vs semaglutide | Tirzepatide users lost more weight than semaglutide users: differences of -2.4% at 3 months, -4.3% at 6 months and -6.9% at 12 months. | Human observationaln = 18386 | JAMA internal medicine 2024, PMID 38976257 |
| Lean mass loss with GLP-1 agonists | Lean mass loss made up approximately 25% of total weight loss across the drug class. | Meta-analysisn = 2258 | Metabolism: clinical and experimental 2025, PMID 39719170 |
Showing the first 20 of 24 rows, strongest sources first.
PubMed records for Tirzepatide and weight loss: 990 human, 49 animal (search counts, not studies we reviewed). Grades follow our evidence scale.
How strong is it?
A human randomized trial outweighs any number of animal studies. Animal and cell results show a mechanism worth testing, not that it works in people.
Other peptides people research for weight loss
All peptides for weight loss, comparedCommon questions
Does Tirzepatide help with weight loss?
The strongest study we summarise for weight loss is human rct evidence, across 16 studies with an outcome for weight loss. A trial result is not an approval; see the legal status.
Is Tirzepatide approved for weight loss?
Tirzepatide is FDA approved (Mounjaro, Zepbound). Which conditions that approval covers is set by the label; use for anything else is off-label.
What is the best peptide for weight loss?
There is no single answer. Our weight loss overview compares each candidate by evidence grade and legal status rather than by popularity.
More on Tirzepatide
DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.
Sources
- 1Ixekizumab With Tirzepatide Achieved Greater Disease Control Than Ixekizumab Alone in Adults With Psoriatic Arthritis and Overweight or Obesity: Results From a Randomized Clinical Trial.Arthritis & rheumatology (Hoboken, N.J.) · 2026PMID 41903163Accessed 2 Oct 2026
- 2Tirzepatide as Compared with Semaglutide for the Treatment of Obesity.The New England journal of medicine · 2025PMID 40353578Accessed 2 Oct 2026
- 3Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight.Diabetes, obesity & metabolism · 2025PMID 39996356Accessed 2 Oct 2026
- 4Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial.JAMA · 2024PMID 38078870Accessed 2 Oct 2026
- 5Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity.The New England journal of medicine · 2024PMID 38912654Accessed 2 Oct 2026
- 6Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial.Lancet (London, England) · 2023PMID 37385275Accessed 2 Oct 2026
- 7Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial.Nature medicine · 2023PMID 37840095Accessed 2 Oct 2026
- 8Tirzepatide Once Weekly for the Treatment of Obesity.The New England journal of medicine · 2022PMID 35658024Accessed 2 Oct 2026
- 9Effect of Subcutaneous Tirzepatide vs Placebo Added to Titrated Insulin Glargine on Glycemic Control in Patients With Type 2 Diabetes: The SURPASS-5 Randomized Clinical Trial.JAMA · 2022PMID 35133415Accessed 2 Oct 2026
- 10Effect of tirzepatide versus insulin degludec on liver fat content and abdominal adipose tissue in people with type 2 diabetes (SURPASS-3 MRI): a substudy of the randomised, open-label, parallel-group, phase 3 SURPASS-3 trial.The lancet. Diabetes & endocrinology · 2022PMID 35468325Accessed 2 Oct 2026
- 11Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial.Lancet (London, England) · 2021PMID 34186022Accessed 2 Oct 2026
- 12Once-weekly tirzepatide versus once-daily insulin degludec as add-on to metformin with or without SGLT2 inhibitors in patients with type 2 diabetes (SURPASS-3): a randomised, open-label, parallel-group, phase 3 trial.Lancet (London, England) · 2021PMID 34370970Accessed 2 Oct 2026
- 13Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity.JAMA internal medicine · 2024PMID 38976257Accessed 2 Oct 2026
- 14Effect of glucagon-like peptide-1 receptor agonists and co-agonists on body composition: Systematic review and network meta-analysis.Metabolism: clinical and experimental · 2025PMID 39719170Accessed 2 Oct 2026
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