Weight-Loss Medications: What the Evidence Shows

Jul 7, 2026 · 5 min readRolf Hoefer, Ph.D.

6 sources reviewedMedically reviewed by Amy Bingaman, MD, MSCP, FACOGArticle updated Sep 25, 2026Our editorial process

The short answer

Semaglutide, tirzepatide, and liraglutide can produce clinically meaningful weight loss in eligible patients when used at weight-management doses. [2] [3] [4] The right choice depends on medical history, side effects, access, treatment goals, and the exact approved product. This is a selected evidence review, not a systematic or comprehensive review of every weight-loss medication study.

What you’ll learn

  • Semaglutide, tirzepatide, and liraglutide have randomized-trial evidence for weight management in eligible patients, but the drugs, doses, populations, and trial designs differ.
  • Dulaglutide is primarily a diabetes medicine and is not approved specifically for chronic weight management in the United States.
  • Counting extracted findings does not establish which medicine has the deepest overall evidence or which one is best for an individual patient.

Bottom line

Semaglutide, tirzepatide, and liraglutide can help eligible patients lose weight, but they should not be ranked by simply counting how many findings appear in a database. Trials use different doses, products, populations, comparators, and follow-up periods. Some enroll people with diabetes, while others specifically study chronic weight management.

The earlier version of this page ranked medicines by the number of extracted findings in our evidence system. That was not a comprehensive count of all studies, and a single paper could contribute several findings. We have removed the ranking.

This page reviews selected evidence. It is not a systematic or comprehensive review of every weight-loss medication trial.

Medicines covered in this review

Medicines covered in this review
MedicineWhat it is used forWhat matters when comparing results
SemaglutideCertain products and doses are approved for chronic weight management; other products are approved for type 2 diabetesProduct, dose, diabetes status, follow-up, side effects, and access
TirzepatideCertain products are approved for chronic weight management or type 2 diabetesDose escalation, gastrointestinal effects, contraindications, and long-term access
LiraglutideAvailable in products approved for chronic weight management or type 2 diabetesIt is injected daily rather than weekly and uses a different dose by indication
DulaglutideApproved for type 2 diabetes in the United StatesWeight change in a diabetes trial is not the same as evidence for an obesity indication

Brand and dose matter. Results from oral semaglutide for diabetes should not be presented as if they directly describe weekly semaglutide used for chronic weight management. The same rule applies when comparing diabetes doses with obesity-treatment doses.

What the selected studies found

In a 26-week phase 2 dose-finding trial in 632 adults with type 2 diabetes, once-daily oral semaglutide at 2.5 mg to 40 mg lowered the three-month blood sugar marker more than placebo. Body weight fell by 2.1 kg to 6.9 kg across the oral doses versus 1.2 kg with placebo, and the weight difference was significant at 10 mg or more. [1] That dose-finding trial in diabetes does not describe a current weight-management prescription. A meta-analysis reported that the one included 12-month liraglutide trial in adults with obesity and without diabetes found a greater reduction in body mass index than placebo. [2] In the 72-week SURMOUNT-1 trial of 2,539 adults with obesity, or overweight with a weight-related complication, and without diabetes, mean weight change was -15.0% with tirzepatide 5 mg, -19.5% with 10 mg, and -20.9% with 15 mg once weekly, versus -3.1% with placebo. [3] In the 68-week STEP 1 trial of 1,961 adults with overweight or obesity and without diabetes, once-weekly semaglutide 2.4 mg plus lifestyle intervention produced a mean body-weight change of -14.9% versus -2.4% with placebo. [4]

AWARD-6, a 26-week open-label trial in 599 adults with type 2 diabetes taking metformin, found once-weekly dulaglutide 1.5 mg non-inferior to once-daily liraglutide 1.8 mg for lowering the three-month blood sugar marker. Both were used at diabetes doses. [5] Registered results from the same trial show slightly greater weight loss with liraglutide (3.61 kg) than with dulaglutide (2.90 kg) at 26 weeks. [6] That result is relevant to diabetes care, but it should not be used to rank dulaglutide alongside medicines studied and approved specifically for chronic weight management.

How clinicians choose among the options

The decision starts with eligibility and medical history. Prior pancreatitis, gallbladder disease, severe gastrointestinal symptoms, pregnancy plans, kidney risk during dehydration, and personal or family history relevant to labeled thyroid warnings can change the discussion.

Practical fit matters too. A medication may work well in a trial but be a poor long-term choice if the patient cannot access it consistently, tolerate dose escalation, eat enough protein, or protect muscle during weight loss. Midlife women may want a plan that includes resistance training, sleep, bone health, and menopause symptoms rather than focusing on the scale alone.

Safety and red flags

These medicines commonly cause nausea, vomiting, diarrhea, constipation, or abdominal discomfort. Severe or persistent abdominal pain, repeated vomiting, inability to keep fluids down, fainting, or signs of dehydration require prompt clinical advice. Sudden severe abdominal pain may need urgent assessment.

Weight-loss medicines are not used during pregnancy. Product labeling and contraindications differ, so the exact prescription should be reviewed rather than treating all glucagon-like peptide-1 (GLP-1) related medicines as interchangeable.

What this review includes

We retained selected cited findings but removed the unsupported evidence ranking. We did not search every database, screen all eligible trials, or grade every comparison. The page therefore describes the evidence reviewed without claiming to measure the total evidence behind each medicine.

The evidence is limited by differences in dose, product, indication, diabetes status, trial length, and follow-up. Those differences make simple study-count comparisons unreliable.

What to ask your clinician

  • Which exact medicine, product, and dose are you recommending, and for what indication?
  • What result is realistic for me, and over what period?
  • Which side effects or medical risks matter most in my case?
  • How will we protect muscle and bone while I lose weight?
  • What is the plan if the medicine becomes unavailable or I need to stop it?

References

[1] Davies M, Pieber TR, Hartoft-Nielsen ML, Hansen OKH, Jabbour S, Rosenstock J. Effect of Oral Semaglutide Compared With Placebo and Subcutaneous Semaglutide on Glycemic Control in Patients With Type 2 Diabetes: A Randomized Clinical Trial. JAMA. 2017;318(15):1460-1470. doi:10.1001/jama.2017.14752 https://pubmed.ncbi.nlm.nih.gov/29049653/

[2] Monami M, Dicembrini I, Marchionni N, Rotella CM, Mannucci E. Effects of glucagon-like peptide-1 receptor agonists on body weight: a meta-analysis. Exp Diabetes Res. 2012;2012:672658. doi:10.1155/2012/672658 https://pubmed.ncbi.nlm.nih.gov/22675341/

[3] Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. doi:10.1056/nejmoa2206038 https://pubmed.ncbi.nlm.nih.gov/35658024/

[4] Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. doi:10.1056/nejmoa2032183 https://pubmed.ncbi.nlm.nih.gov/33567185/

[5] Dungan KM, Povedano ST, Forst T, et al. Once-weekly dulaglutide versus once-daily liraglutide in metformin-treated patients with type 2 diabetes (AWARD-6): a randomised, open-label, phase 3, non-inferiority trial. Lancet. 2014;384(9951):1349-57. doi:10.1016/s0140-6736(14)60976-4 https://pubmed.ncbi.nlm.nih.gov/25018121/

[6] ClinicalTrials.gov. A randomized, open-label, parallel-arm study comparing the effect of once-weekly dulaglutide with once-daily liraglutide in patients with type 2 diabetes (AWARD-6). NCT01624259. Study results. https://clinicaltrials.gov/study/NCT01624259?tab=results

Common questions

Which weight-loss medication works best?

Head-to-head evidence can inform this question, but no single answer applies to everyone. The exact product and dose, diabetes status, side effects, contraindications, access, and ability to continue treatment all matter.[1][2][3][4][5]

Are semaglutide and tirzepatide the same?

No. They act on different combinations of hormone receptors and use different dosing schedules. Results from one drug or dose should not be transferred to another.[1][3][4]

Is dulaglutide a weight-loss medication?

Dulaglutide is approved for type 2 diabetes, not specifically for chronic weight management in the United States. Some diabetes trials report weight change, but that does not make it interchangeable with an approved obesity treatment.[5][6]

Why was the earlier ranking removed?

It counted findings extracted into a limited evidence database, not all clinical trials. That count could not reliably measure the complete evidence behind each medication.[1][2][3][4][5]

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