Obesity affects hundreds of millions of people worldwide and is now considered one of the biggest public health problems of modern times.
Carrying too much body fat increases the risk of many serious illnesses, including type 2 diabetes, heart disease, stroke, sleep disorders, fatty liver disease, certain cancers, and joint problems. Many people also struggle emotionally because obesity can affect confidence, mental health, and daily life.
For decades, doctors have searched for treatments that can help people lose weight safely and keep it off long term.
Diet and exercise remain important, but many people find it extremely difficult to maintain large weight losses over many years. This is because the body naturally fights against weight loss by increasing hunger and slowing metabolism.
Recently, a new generation of obesity medicines has attracted worldwide attention. These drugs, known as GLP-1 receptor agonists, include medications such as semaglutide and liraglutide. Another newer medicine called tirzepatide targets two hormone systems at once and is sometimes called a dual agonist.
These medicines work by copying natural hormones involved in appetite and digestion. They help people feel fuller after eating, reduce cravings, and slow how quickly food leaves the stomach. Many patients taking these drugs have lost significant amounts of weight, leading to excitement among doctors and patients.
However, rapid weight loss has also raised concerns. Some experts worried that people using GLP-1 drugs might lose too much muscle along with fat.
Muscle is extremely important for physical strength, healthy aging, balance, movement, and maintaining metabolism. In older adults especially, losing muscle can increase the risk of weakness and falls.
New research now suggests those fears may be smaller than many people expected.
The study was presented at the European Congress on Obesity (ECO2026) held in Istanbul, Turkey. The research team came from the Metabolism Center N°12 Antonigasse and the Medical University of Vienna in Austria.
The researchers analyzed data from 486 adults with obesity who received treatment between 2022 and 2025 at a specialized obesity clinic in Vienna. The average participant was about 50 years old and had a BMI of around 37.7, indicating significant obesity.
Most participants were treated with semaglutide, while smaller numbers used liraglutide or tirzepatide. Patients also received advice about exercise and physical activity during treatment.
To study body changes carefully, the researchers used a technique called bioelectrical impedance analysis. This method measures body composition by sending a very weak electrical signal through the body.
Since muscle contains more water and conducts electricity better than fat, the machine can estimate how much muscle and fat a person has.
This type of analysis is important because weight alone does not tell the whole story. Two people can lose the same amount of weight but experience very different health effects depending on whether the lost weight comes mostly from fat or muscle.
After around 14 months of treatment, patients lost nearly 10% of their body weight on average. The researchers found that most of this reduction came from body fat. Fat mass dropped by approximately 9 kilograms, which represented about 18% of total fat mass.
At the same time, muscle loss remained relatively small. Skeletal muscle mass decreased by only about 1.2 kilograms, around 5% overall. More importantly, over 70% of patients maintained or improved their relative muscle mass during treatment.
The researchers used advanced computer analysis to account for repeated measurements and factors such as age, sex, BMI, and changes in fat mass. After adjusting for these variables, they found that muscle mass stayed relatively stable over time.
This suggested that the medications mainly produced healthy fat loss rather than dangerous muscle wasting.
The findings are important because many doctors have been debating whether GLP-1 drugs may unintentionally weaken patients by reducing muscle. This study provides reassuring evidence that most weight reduction comes from fat instead.
The study also reflects a broader change in obesity medicine. Experts increasingly recognize that obesity is not simply about body weight. Body composition, metabolism, muscle preservation, inflammation, and long-term physical function are all critical parts of health.
Even so, the researchers stressed that the study has limitations. Because it was retrospective, it relied on previously collected medical records rather than carefully controlled experiments.
The study also did not include a placebo comparison group, and most participants were women, which limits how widely the findings can be applied.
The scientists emphasized that more long-term clinical trials are needed to fully understand how these medicines affect muscle and body composition over many years of treatment.
Still, the results are encouraging for patients considering obesity medications. The findings suggest that modern GLP-1 treatments may help people lose unhealthy body fat while largely protecting important muscle tissue.
If you care about weight loss, please read studies about orange that could help obesity, and a berry that can prevent cancer, diabetes and obesity.
For more health information, please see recent studies about ginger’s journey in weight management ,and green tea: a cup of weight loss.
The research was presented at the European Congress on Obesity (ECO2026) in Istanbul.
Source: Medical University of Vienna.
