- A new study found that several newer medications can aid in significant weight loss.
- However, the most effective drugs produced more side effects, often leading people to quit.
- Experts say the lesson here is to look beyond weight loss.
- Patients need effective strategies for managing side effects.
In recent years, the number of highly effective medications for the treatment of obesity has grown rapidly
In addition to helping people lose weight, these drugs can also help reduce heart disease risk as well as improve other obesity-related conditions like type 2 diabetes and sleep apnea
However, as the number of new drugs increases, physicians must now choose the right obesity treatment for each patient, balancing benefits and adverse effects
A comprehensive new study has evaluated the effectiveness and safety of medications designed to aid weight loss for adults who are living with overweight or obesity
The analysis, published on July 8, 2026, in The BMJ
, sheds light on which drugs produce the greatest weight loss, their potential side effects, and their impact on health outcomes such as heart disease and quality of life
This information aims to help patients, doctors, and policymakers make informed decisions about obesity treatments
How researchers compared weight loss drugs to each other
Researchers conducted a systematic review and network meta-analysis, a method that allows comparison of multiple treatments even when they haven’t been directly tested against each other
The study included randomized controlled trials lasting at least 12 weeks, involving adults with overweight or obesity, with or without related health issues like diabetes or heart disease
Altogether, nearly 100,000 participants were enrolled across 262 clinical trials
The trials compared 19 weight-loss drugs with lifestyle changes alone, placebo, or other medications
Data were collected from major medical databases through November 2025, including MEDLINE, EMBASE, and the Cochrane Library
The researchers looked at 24 outcomes, including percentage of body weight lost, changes in waist circumference, changes in fat and muscle mass, side effects (including gastrointestinal symptoms and fatigue), rates of discontinuing treatment due to adverse events, and serious health outcomes such as heart attacks and death
They also examined factors such as trial duration, drug dosage, and patient characteristics to determine how they might affect results
The most effective drugs also had the most side effects
The researchers found that two medications stood out for producing the greatest reductions in body weight after one year: tirzepatide and cagrilinitide-semaglutide. Both led to about 15% weight loss
Other drugs with meaningful effects included oral semaglutide, orforglipron, subcutaneous semaglutide, and phentermine-topiramate, which helped participants lose between 8% and 11% of their body weight
Emerging treatments like ecnoglutide, mazdutide, and retatrutide also showed promise for significant weight loss, though evidence for these newer drugs is still limited
The study also highlighted that greater weight loss often came with increased side effects, such as nausea, diarrhea, and fatigue, which sometimes led to patients stopping their medication. Drugs like orforglipron and naltrexone-bupropion had the highest rates of discontinuation due to adverse events
Another important finding was the loss of lean mass, particularly with tirzepatide and subcutaneous semaglutide. While these drugs reduced fat mass effectively, they also caused an average lean mass loss of 6% to 8%, which could affect muscle strength and overall health, especially in older adults
In terms of serious health outcomes, subcutaneous semaglutide was the only drug linked with lower risks of death from any cause and heart attacks. Both subcutaneous semaglutide and tirzepatide reduced the risk of heart failure, with tirzepatide also lowering hospital admissions for heart failure. No drug convincingly reduced the risk of kidney failure
Despite these health benefits and weight loss, none of the drugs showed meaningful improvements in quality of life scores after one year, suggesting that weight loss alone may not translate to better overall well-being in the short term
The study also found that longer treatment duration, especially beyond a year, was associated with larger weight reductions for subcutaneous semaglutide. However, other patient factors, such as diabetes status or baseline obesity severity, did not significantly affect drug effectiveness
Overall, the research suggests a trade-off: the most effective weight-loss drugs tend to have more side effects and higher rates of treatment discontinuation
This information is vital for patients and healthcare providers to consider when choosing the best obesity management strategy
Successful patients use strategies for managing side effects from weight loss drugs
Stephen Cosentino, DO, a board certified physician and Founder and Medical Director of Empire Medical Training, who was not involved in the study, said that, in a nutshell, even though the scale may be trending downward, if people feel tired, nauseous, or fearful about physical changes such as hair or muscle loss, these things can all impact their quality of life
“The takeaway is that the drugs aren’t failing at what they promise to do (facilitate weight loss); rather, we need to better optimize their use,” he said
According to Cosentino, GLP-1 drugs work better for people who:
- take their medication slowly
- eat a balanced amount of protein
- maintain sufficient water intake
- eat small, more frequent meals
- engage in resistance training
- incorporate supplements like vitamin D and calcium
“We need to be thinking beyond the scale, not just asking, ‘How much did you lose?’” he added
Concluding his remarks, Cosentino said, “The ultimate lesson here is that the decrease in number is not the same as an overall increase in life satisfaction, especially if we disregard potential side effects like nausea, hair loss, muscle wasting, and decreased bone density.”
To help patients succeed, physicians need to equip them with strategies to minimize side effects
