What do the weight-loss injections actually do?

Appears under: Weight loss and GLP-1 · Skin aging

The studies

• 5 Repeated evidence Efficacy and safety of tirzepatide, GLP-1 receptor agonists, and other weight loss drugs in overweight and obesity: a network meta-analysis.
  2025 · Obesity (Silver Spring, Md.) · 35,000 participants
• 4 Large controlled trial Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial.
  2024 · JAMA · 783 participants
• 4 Large controlled trial Tirzepatide Once Weekly for the Treatment of Obesity.
  2022 · The New England journal of medicine · 2,539 participants
• 4 Large controlled trial Once-Weekly Semaglutide in Adults with Overweight or Obesity.
  2021 · The New England journal of medicine · 1,961 participants
• 5 Repeated evidence A systematic review of the effect of semaglutide on lean mass: insights from clinical trials.
  2024 · Expert opinion on pharmacotherapy
• 5 Repeated evidence Efficacy and safety of once-weekly tirzepatide for weight management compared to placebo: An updated systematic review and meta-analysis including the latest SURMOUNT-2 trial.
  2024 · Endocrine
• 5 Repeated evidence Potent incretin-based therapy for obesity: A systematic review and meta-analysis of the efficacy of semaglutide and tirzepatide on body weight and waist circumference, and safety.
  2024 · Obesity reviews : an official journal of the Internatio · 5,140 participants
• 5 Repeated evidence Effect of Glucagon-like Peptide-1 Receptor Agonists (GLP-1RA) on Weight Loss Following Bariatric Treatment.
  2024 · The Journal of clinical endocrinology and metabolism · 1,164 participants
• 5 Repeated evidence The quantity, quality and findings of network meta-analyses evaluating the effectiveness of GLP-1 RAs for weight loss: a scoping review.
  2026 · Health technology assessment (Winchester, England)
• 5 Repeated evidence Once-Weekly Semaglutide Versus Once-Daily Liraglutide for Weight Loss in Adults: A Meta-Analysis of Randomized Controlled Trials.
  2025 · Clinical and translational science · 922 participants
• 4 Large controlled trial Healthy Weight Loss Maintenance with Exercise, Liraglutide, or Both Combined.
  2021 · The New England journal of medicine · 195 participants
• 4 Large controlled trial Efficacy and safety of once-weekly tirzepatide in Japanese patients with obesity disease (SURMOUNT-J): a multicentre, randomised, double-blind, placebo-controlled phase 3 trial.
  2025 · The lancet. Diabetes & endocrinology · 413 participants · manufacturer helped fund this
• 5 Repeated evidence Who Wins the Battle Against Obesity? A Network Meta-Analysis Comparing Tirzepatide and Semaglutide.
  2026 · Journal of diabetes · 367 participants
• 5 Repeated evidence Liraglutide and cardiovascular outcomes in adults with overweight or obesity: A post hoc analysis from SCALE randomized controlled trials.
  2018 · Diabetes, obesity & metabolism · 5,908 participants · manufacturer helped fund this
• 5 Repeated evidence Efficacy and Safety of Cagrilintide and Cagrisema Versus Semaglutide as Anti-Obesity Medications: A Systematic Review, Meta-Analysis and Meta-Regression.
  2026 · Diabetes, obesity & metabolism · 3,545 participants
• 5 Repeated evidence Efficacy and Safety of the New Appetite Suppressant, Liraglutide: A Meta-Analysis of Randomized Controlled Trials.
  2022 · Endocrinology and metabolism (Seoul, Korea) · 8,060 participants
• 4 Large controlled trial A randomized, double-blind, placebo-controlled trial of weight loss using liraglutide 3.0 mg for weight recurrence after Roux-en-Y gastric bypass.
  2025 · Surgery for obesity and related diseases : official jou · 132 participants
• 4 Large controlled trial Psychiatric Safety of Semaglutide for Weight Management in People Without Known Major Psychopathology: Post Hoc Analysis of the STEP 1, 2, 3, and 5 Trials.
  2024 · JAMA internal medicine · 3,377 participants
• 4 Large controlled trial Effect of liraglutide 3.0 mg in individuals with obesity and moderate or severe obstructive sleep apnea: the SCALE Sleep Apnea randomized clinical trial.
  2018 · International journal of obesity (2005) · 180 participants · manufacturer helped fund this
• 5 Repeated evidence Patient initiation and maintenance of GLP-1 RAs for treatment of obesity: a narrative review and practical considerations for primary care providers.
  2021 · Postgraduate medicine
• 4 Large controlled trial Tirzepatide and health-related quality of life in adults with obesity or overweight: Results from the SURMOUNT-3 phase 3 randomized trial.
  2025 · Diabetes, obesity & metabolism · 292 participants
• 4 Large controlled trial Weight maintenance and additional weight loss with liraglutide after low-calorie-diet-induced weight loss: the SCALE Maintenance randomized study.
  2014 · International journal of obesity (2005) · 422 participants
• 4 Large controlled trial Liraglutide 3.0 mg and Intensive Behavioral Therapy (IBT) for Obesity in Primary Care: The SCALE IBT Randomized Controlled Trial.
  2020 · Obesity (Silver Spring, Md.) · 142 participants · manufacturer helped fund this
• 4 Large controlled trial Time to weight plateau with tirzepatide treatment in the SURMOUNT-1 and SURMOUNT-4 clinical trials.
  2025 · Clinical obesity · 1,438 participants · manufacturer helped fund this
• 4 Large controlled trial One Year of Exercise After Weight Loss Increases Postprandial GLP-1 Secretion in Contrast to Usual Activity or GLP-1 Receptor Agonist Treatment.
  2025 · Obesity (Silver Spring, Md.) · 195 participants
• 5 Repeated evidence Effects of GLP-1 Receptor Agonists on Skin Quality: A Comprehensive Literature Review.
  2026 · Aesthetic plastic surgery
• 5 Repeated evidence Exploring the Efficacy and Safety of Tirzepatide in Obesity Management and Cardiometabolic Risk Factors: A Comprehensive Systematic Review and Meta-Analysis.
  2025 · Clinical obesity · 6,257 participants
• 5 Repeated evidence A Systematic Review and Meta-Analysis of Semaglutide Effects on Adipose Tissue and Emerging Effects on Brain and Cognition.
  2026 · Obesity reviews : an official journal of the Internatio · 23 participants
• 5 Repeated evidence GLP-1RA- and Incretin-Based Therapies Within Lifestyle Interventions for Adults with Overweight or Obesity: A Systematic Review and Meta-Analysis.
  2026 · Nutrients
• 5 Repeated evidence Weight Changes With Tirzepatide and Concomitant Weight-Inducing Medications: Post Hoc Analysis of Randomized Clinical Trials.
  2026 · JAMA network open · 442 participants · manufacturer helped fund this
• 5 Repeated evidence Effectiveness & safety of semaglutide in weight reduction in obese nondiabetic patients: A systematic review and meta-analysis.
  2026 · Medicine · 3,613 participants
• 5 Repeated evidence Mental health outcomes in obesity interventions with GLP-1 receptor agonists: is it similar to other obesity interventions? A narrative review with systematic evidence synthesis.
  2026 · International journal of obesity (2005)
• 5 Repeated evidence Weight Reduction Heterogenicity and Mediators of GLP-1RAs and Dual Agonists for Individuals With Obesity: A Meta-Analysis.
  2026 · Clinical obesity · 408 participants
• 4 Large controlled trial Weight reduction over time in tirzepatide-treated participants by early weight loss response: Post hoc analysis in SURMOUNT-1.
  2025 · Diabetes, obesity & metabolism · 1,545 participants · manufacturer helped fund this
• 4 Large controlled trial Apitegromab for lean mass preservation during tirzepatide-induced weight loss: a randomized, double-blind, placebo-controlled phase 2 trial.
  2026 · Nature medicine · 102 participants · manufacturer helped fund this
• 4 Large controlled trial Analysis of Tirzepatide Acquisition Costs and Weight Reduction Outcomes in the United Kingdom: Insights from the SURMOUNT-1 Study.
  2025 · Advances in therapy · 2,539 participants · manufacturer helped fund this
• 4 Large controlled trial Tolerability of nausea and vomiting and associations with weight loss in a randomized trial of liraglutide in obese, non-diabetic adults.
  2015 · International journal of obesity (2005) · 564 participants
• 4 Large controlled trial Effects of Dietary Self-Monitoring, Physical Activity, Liraglutide 3.0 mg, and Placebo on Weight Loss in the SCALE IBT Trial.
  2021 · Obesity facts · 142 participants · manufacturer helped fund this
• 4 Large controlled trial Tirzepatide and change in uric acid and its association with weight reduction: post hoc analyses of the SURMOUNT-1 randomised placebo-controlled trial.
  2026 · Annals of the rheumatic diseases · 2,539 participants
• 4 Large controlled trial Efficacy and safety of liraglutide 3.0 mg for weight management are similar across races: subgroup analysis across the SCALE and phase II randomized trials.
  2016 · Diabetes, obesity & metabolism · 5,325 participants
• 4 Large controlled trial Semaglutide Injection Once-Weekly for Weight Management in Adults: Results From A Randomized Phase III, Active-Controlled Study.
  2026 · Diabetes, obesity & metabolism · 270 participants · manufacturer helped fund this
• 4 Large controlled trial Tirzepatide compared with semaglutide in obesity disease: a subpopulation analysis applying Japan Society for the Study of Obesity criteria in the global SURMOUNT-5 trial.
  2026 · Current medical research and opinion · 750 participants
• 4 Large controlled trial Tirzepatide Efficacy and Tolerability According to Early Weight Response: A Post Hoc Analysis of the SURMOUNT-1 and SURMOUNT-2 Trials.
  2026 · Diabetes, obesity & metabolism · 2,384 participants · manufacturer helped fund this