Three new Cochrane reviews find evidence that GLP-1 drugs lead to clinically meaningful weight loss, though industry-funded studies raise concerns.
Three new reviews from Cochrane have found that GLP-1 medications can lead to significant weight loss, though questions remain about the influence of industry-funded research. Commissioned by the World Health Organization (WHO), these reviews will help shape forthcoming global guidelines on using these drugs to treat obesity.
The analyses focused on three medications known as GLP-1 receptor agonists and concluded that each produced clinically meaningful weight loss when compared with a placebo. However, researchers noted that data on long-term effects, side effects, and possible conflicts of interest are still uncertain or incomplete.
Glucagon-like peptide-1 (GLP-1) receptor agonists were first developed in the mid-2000s to help manage type 2 diabetes. In patients with this condition, particularly those with heart or kidney disease, the drugs improved blood sugar control, lowered the risk of related complications, aided in weight reduction, and decreased the likelihood of premature death.
In recent years, these drugs have also been tested in people with obesity. By mimicking a natural hormone that slows digestion and promotes a sense of fullness, they can help reduce food intake. In the United Kingdom, GLP-1 receptor agonists are now approved for weight management in individuals with obesity, or in those who are overweight with health conditions linked to excess weight, when combined with a calorie-controlled diet and physical activity.
GLP-1 Drugs: Generic [and Brand Names]:
- Semaglutide [Ozempic, Wegovy, Rybelsus]
- Liraglutide [Victoza, Saxenda]
- Dulaglutide [Trulicity]
- Exenatide [Byetta, Bydureon]
- Tirzepatide (GLP-1/GIP dual agonist) [Mounjaro, Zepbound]
GLP-1 drugs show promise for weight management
Across the reviews, tirzepatide, semaglutide, and liraglutide each led to significant weight loss compared to placebo after one to two years, with these effects likely to be sustained while treatment continues.
- Tirzepatide (administered once weekly) resulted in approximately a 16% weight reduction after 12 to 18 months. Evidence from 8 randomized controlled trials (6,361 participants) also suggested these effects could be maintained for up to 3.5 years, although long-term safety data were limited.
- Semaglutide (also injected weekly) reduced body weight by around 11% after 24 to 68 weeks, with effects likely sustained up to two years, drawing on 18 randomized controlled trials (27,949 participants). The drug increased the likelihood of achieving at least 5% body weight loss but was associated with higher rates of mild-to-moderate gastrointestinal side effects.
- Liraglutide (a daily injection) resulted in a more modest average weight reduction of around 4–5%, based on 24 trials (9,937 participants), but still increased the proportion of people achieving meaningful weight loss compared with placebo. Evidence for longer-term effects beyond two years was more limited.
Across the reviews, there was little to no difference between these drugs and placebo for major cardiovascular events, quality of life, or mortality. However, adverse events, particularly nausea and digestive symptoms, were more common among participants taking GLP-1 drugs, and some stopped treatment due to side effects.
“These drugs have the potential to bring about substantial weight loss, particularly in the first year,” says Juan Franco, co-lead researcher from Heinrich Heine University Düsseldorf, Germany. “It’s an exciting moment after decades of unsuccessful attempts to find effective treatments for people living with obesity.”
Independent research and equitable access are key
Most included studies were funded by the drug manufacturers, who were substantially involved in the planning, conduct, analysis, and reporting of the results. This raises concerns about potential conflicts of interest and the need for independent research.
The authors also emphasized that the wider use of these drugs should consider social and commercial determinants of health, including access, affordability, and insurance coverage, to avoid deepening existing health inequities among people living with obesity. The high prices of semaglutide and tirzepatide currently limit access, while liraglutide’s expired patent has allowed for more affordable generic versions to become available. Semaglutide’s patent will also expire in 2026.
Studies included in all three reviews were conducted mainly in middle- and high-income countries, with limited or no representation from regions such as Africa, Central America, and Southeast Asia. Considering the diversity in body composition, diet, and health behaviors across populations, the authors note the importance of assessing how these drugs perform in different global contexts.
“We need more data on the long-term effects and other outcomes related to cardiovascular health, particularly in lower-risk individuals,” says Eva Madrid, co-lead researcher from the Universidad de Valparaíso, Chile. “Weight regain after stopping treatment may affect the long-term sustainability of the observed benefits. More independent studies from a public health perspective are needed.”
The reviews stress that independent, long-term investigations are essential to inform clinical and public policy decisions and to better establish the role of GLP-1 receptor agonists in long-term weight management.
Commissioned by the World Health Organization, these reviews will inform forthcoming WHO guidelines on the use of GLP-1 receptor agonists for treating obesity. The guidelines are expected to launch soon, following a public consultation held in September.
References:
“Liraglutide for adults living with obesity” by Nicolás Meza, Javier Bracchiglione, Camila Micaela Escobar Liquitay, Eva Madrid, Lucia B Varela, Yang Guo, Gerard Urrútia, Selcuk Er, Sandra Tiller, Kamyar Shokraee, Felipe Alvarez Busco, Ivan Solà, Miranda Ocara Vargas, Victoria Novik A, Daniel Poloni and Juan VA Franco, 30 October 2025, Cochrane Database of Systematic Reviews.
DOI: 10.1002/14651858.CD016017
“Semaglutide for adults living with obesity” by Javier Bracchiglione, Nicolás Meza, Juan VA Franco, Camila Micaela Escobar Liquitay, Victoria Novik A, Miranda Ocara Vargas, Gabriel Lazcano, Daniel Poloni, Francisca Rinaldi Langlotz, Marta Roqué-Figuls, Sergio R Munoz and Eva Madrid, 30 October 2025, Cochrane Database of Systematic Reviews.
DOI: 10.1002/14651858.CD015092.pub2
“Tirzepatide for adults living with obesity” by Juan VA Franco, Yang Guo, Lucia B Varela, Zakariya Aqra, Murad Alhalahla, Mauricio Medina Rodriguez, Edison Leonardo Salvador Oscco, Bernarda Patiño Araujo, Susan Banda, Camila Micaela Escobar Liquitay, Javier Bracchiglione, Nicolás Meza and Eva Madrid, 30 October 2025, Cochrane Database of Systematic Reviews.
DOI: 10.1002/14651858.CD016018
News
Platelet-inspired nanoparticles could improve treatment of inflammatory diseases
Scientists have developed platelet-inspired nanoparticles that deliver anti-inflammatory drugs directly to brain-computer interface implants, doubling their effectiveness. Scientists have found a way to improve the performance of brain-computer interface (BCI) electrodes by delivering anti-inflammatory drugs directly [...]
After 150 years, a new chapter in cancer therapy is finally beginning
For decades, researchers have been looking for ways to destroy cancer cells in a targeted manner without further weakening the body. But for many patients whose immune system is severely impaired by chemotherapy or radiation, [...]
Older chemical libraries show promise for fighting resistant strains of COVID-19 virus
SARS‑CoV‑2, the virus that causes COVID-19, continues to mutate, with some newer strains becoming less responsive to current antiviral treatments like Paxlovid. Now, University of California San Diego scientists and an international team of [...]
Lower doses of immunotherapy for skin cancer give better results, study suggests
According to a new study, lower doses of approved immunotherapy for malignant melanoma can give better results against tumors, while reducing side effects. This is reported by researchers at Karolinska Institutet in the Journal of the National [...]
Researchers highlight five pathways through which microplastics can harm the brain
Microplastics could be fueling neurodegenerative diseases like Alzheimer's and Parkinson's, with a new study highlighting five ways microplastics can trigger inflammation and damage in the brain. More than 57 million people live with dementia, [...]
Tiny Metal Nanodots Obliterate Cancer Cells While Largely Sparing Healthy Tissue
Scientists have developed tiny metal-oxide particles that push cancer cells past their stress limits while sparing healthy tissue. An international team led by RMIT University has developed tiny particles called nanodots, crafted from a metallic compound, [...]
Gold Nanoclusters Could Supercharge Quantum Computers
Researchers found that gold “super atoms” can behave like the atoms in top-tier quantum systems—only far easier to scale. These tiny clusters can be customized at the molecular level, offering a powerful, tunable foundation [...]
A single shot of HPV vaccine may be enough to fight cervical cancer, study finds
WASHINGTON -- A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported Wednesday. HPV, or human papillomavirus, is very common and spread [...]
New technique overcomes technological barrier in 3D brain imaging
Scientists at the Swiss Light Source SLS have succeeded in mapping a piece of brain tissue in 3D at unprecedented resolution using X-rays, non-destructively. The breakthrough overcomes a long-standing technological barrier that had limited [...]
Scientists Uncover Hidden Blood Pattern in Long COVID
Researchers found persistent microclot and NET structures in Long COVID blood that may explain long-lasting symptoms. Researchers examining Long COVID have identified a structural connection between circulating microclots and neutrophil extracellular traps (NETs). The [...]
This Cellular Trick Helps Cancer Spread, but Could Also Stop It
Groups of normal cbiells can sense far into their surroundings, helping explain cancer cell migration. Understanding this ability could lead to new ways to limit tumor spread. The tale of the princess and the [...]
New mRNA therapy targets drug-resistant pneumonia
Bacteria that multiply on surfaces are a major headache in health care when they gain a foothold on, for example, implants or in catheters. Researchers at Chalmers University of Technology in Sweden have found [...]
Current Heart Health Guidelines Are Failing To Catch a Deadly Genetic Killer
New research reveals that standard screening misses most people with a common inherited cholesterol disorder. A Mayo Clinic study reports that current genetic screening guidelines overlook most people who have familial hypercholesterolemia, an inherited disorder that [...]
Scientists Identify the Evolutionary “Purpose” of Consciousness
Summary: Researchers at Ruhr University Bochum explore why consciousness evolved and why different species developed it in distinct ways. By comparing humans with birds, they show that complex awareness may arise through different neural architectures yet [...]
Novel mRNA therapy curbs antibiotic-resistant infections in preclinical lung models
Researchers at the Icahn School of Medicine at Mount Sinai and collaborators have reported early success with a novel mRNA-based therapy designed to combat antibiotic-resistant bacteria. The findings, published in Nature Biotechnology, show that in [...]
New skin-permeable polymer delivers insulin without needles
A breakthrough zwitterionic polymer slips through the skin’s toughest barriers, carrying insulin deep into tissue and normalizing blood sugar, offering patients a painless alternative to daily injections. A recent study published in the journal Nature examines [...]
