Obesity has become a growing global health challenge. According to the World Health Organization (WHO), obesity was associated with nearly 3.7 million deaths worldwide in 2024, and the number of people living with obesity could double by 2030 if strong action is not taken. In recent years, medications known as GLP-1 drugs to manage type 2 diabetes and weight issues, have gained attention. In fact, in September 2025, the WHO added GLP-1 therapies to its Essential Medicines List for high-risk diabetes patients and recommended their use in obesity management as part of a comprehensive approach. But while some people lose significant weight with these drugs, others may not see the same results.
What are GLP-1 medications?
GLP-1 medications, also called GLP-1 receptor agonists, are drugs that mimic a natural hormone in the body known as glucagon-like peptide-1. This hormone is released by the gut after eating and sends signals to the brain that the body has had enough food.
When we eat, carbohydrates are broken down into glucose, which enters the bloodstream. GLP-1 stimulates the pancreas to release insulin, helping move glucose into the body’s cells for energy.
“Medications such as semaglutide and tirzepatide replicate this natural process. They work by regulating appetite, controlling blood sugar levels, and slowing stomach emptying. Originally developed to treat diabetes, these drugs are now widely used in obesity treatment,” explains Dr Rajiv Kovil, Head of Diabetology and weight loss expert at Zandra Healthcare. He adds GLP-1 medications work with the body’s natural satiety signals rather than against them.
How do GLP-1 drugs help with weight loss?
GLP-1 medicines help reduce weight by improving the communication between the brain and the gut that controls hunger. These drugs act on appetite centres in the brain, especially the hypothalamus and reward systems. As a result, people tend to feel full faster and stay satisfied for longer. They may naturally eat smaller portions and experience fewer cravings.
GLP-1 medications also slow the emptying of the stomach and help stabilise blood sugar levels. This prevents sudden hunger spikes that often occur after meals. Clinical studies show encouraging results. Research has found that many people taking GLP-1 drugs can lose around 10–15 percent of their body weight when the medication is combined with healthy eating and regular physical activity.
In one study published in Touch Reviews in Endocrinology, nearly 2,000 people with a Body Mass Index of 30 or higher were followed for 68 weeks. Participants receiving semaglutide lost almost 15 percent of their body weight on average, compared to about 2.5 percent in the placebo group.
Why do some people not lose weight on GLP-1 drugs?
Despite promising results, GLP-1 medications do not work the same way for everyone. Obesity is influenced by multiple hormones, brain pathways, genetics, and lifestyle factors. GLP-1 is only one part of this complex metabolic system. According to Dr Kovil, in some individuals, other appetite-regulating hormones or neural circuits may play a stronger role. This means that GLP-1 signals alone may not be powerful enough to significantly change metabolism or weight.
This is also why newer treatments such as tirzepatide or other emerging therapies target multiple hormonal pathways instead of just GLP-1. Other factors that may affect results include:
- Genetic differences
- Existing medications
- Hormonal or endocrine disorders
- Metabolic rate
- Lifestyle patterns such as sleep, stress, and physical activity
It is due to these variables, some people may need a more personalised treatment plan rather than relying on a single medication.
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Signs the medication is working, even if the scale has not changed
Interestingly, weight loss on the scale is not always the first sign that GLP-1 therapy is working. Many patients notice other positive changes before seeing major weight reduction. Some common early signs include:
- Feeling satisfied with smaller portions
- Less frequent snacking or grazing
- Reduced cravings
- Thinking about food less often
- Leaving food unfinished more easily
- More stable energy levels throughout the day
- Clothes fit slightly differently
These changes indicate that the body’s appetite and metabolic signals are shifting in the right direction.
How long does GLP-1 weight loss take?
Weight loss with GLP-1 medications can take time and varies widely between individuals. “Some people notice the effects quickly, while others may need higher doses or longer treatment before they see results,” explains Dr Kovil.
Research suggests that many patients may eventually lose 15–20 percent of their body weight with medications like semaglutide when used consistently alongside healthy lifestyle changes. Experts emphasise that these medications work best as part of a long-term medical strategy, including balanced nutrition, physical activity, and ongoing clinical supervision.
In short, GLP-1 drugs are powerful tools in the fight against obesity, but they are not a one-size-fits-all solution. Understanding how the body responds and working closely with medical professionals can help people achieve more sustainable weight loss results.
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