In a world where, according to the WHO, overweight and obesity are among the leading causes of death and disability in the European Region, innovative treatment methods are increasingly moving into the focus of medical research and practice. Among these new approaches, weight-loss injections have emerged as a promising option for weight reduction. These medical injections, based on the action of GLP-1 medications, offer a unique opportunity to influence metabolism, increase the feeling of satiety, and reduce appetite. With active ingredients such as semaglutide, tirzepatide, and liraglutide, which mimic the effect of the natural digestive hormone GLP-1, weight-loss injections aim to promote weight loss through a combination of reduced food intake and improved metabolism. But how exactly do these injections work, and who are they suitable for? This article illuminates the science behind weight-loss injections, examines their effectiveness, potential side effects, and the criteria for treatment to provide a comprehensive understanding of this modern therapy option.
What are weight-loss injections?
Weight-loss injections, also known as weight-reduction injections, belong to the group of GLP-1 medications and are administered daily or weekly. They contain active ingredients that influence metabolism, increase the feeling of satiety, and reduce appetite. In the media, they are also referred to as weight-loss shots or weight-loss drugs.
How do weight-loss injections work?
Weight-loss injections contain active ingredients (e.g., semaglutide in Wegovy and Ozempic, tirzepatide in Mounjaro, and liraglutide in Saxenda) that are synthetic versions of the GLP-1 hormone. GLP-1 (glucagon-like peptide-1) is a naturally occurring digestive hormone in the human body that is released after eating. It stimulates the release of insulin, regulates blood sugar levels, promotes satiety, and reduces appetite. GLP-1 medications aim to simulate or enhance the effect of GLP-1, which is why they are also called GLP-1 analogues. Taking them reduces the feeling of hunger and leads to an earlier feeling of fullness. This results in reduced food intake and, ultimately, weight loss.
Summary of the effects of weight-loss injections
- Regulated blood sugar levels When there is a lot of sugar in the blood, or one has eaten a great deal, GLP-1 stimulates the pancreas to release more insulin and less glucagon. Insulin lowers blood sugar levels, while glucagon raises them. Less glucagon and more insulin means a lower blood sugar level.
- Delayed gastric emptying GLP-1 causes the stomach to empty more slowly, and at the same time, blood sugar does not spike as quickly immediately after eating. This provides a prolonged feeling of satiety. Users report a feeling of fullness and thus a clear signal that they have eaten enough.
- Less appetite People with obesity often have a larger appetite center in the brain. GLP-1 also docks onto receptors in the brain and sends satiety signals. In studies, the effect was examined as follows: Participants were shown photos of ice cream, fries, or pizza while inside an MRI scanner. The areas in the brain responsible for appetite and reward (insula and amygdala) react more strongly in people with severe obesity than in lean people. When researchers administered an active ingredient that blocks GLP-1 receptors in the brain beforehand, brain activity decreased. The participants consequently had less appetite and ate less afterward.
What types of weight-loss injections and active ingredients are there?
There are various branded products from pharmaceutical companies with different active ingredients. Semaglutide (Ozempic and Wegovy), liraglutide (Saxenda), and tirzepatide (Mounjaro) are all active ingredients used in the treatment of overweight and obesity. They all belong to a class of drugs known as GLP-1 receptor agonists, with the exception of tirzepatide, which also exhibits the properties of a GIP receptor agonist. Despite their similarities, these active ingredients show specific differences:
Semaglutide, liraglutide, tirzepatide - how do the active ingredients in weight-loss injections differ?
Similarities between semaglutide, liraglutide, and tirzepatide
- GLP-1 receptor agonism: Both semaglutide and liraglutide mimic the effect of the body's own hormone GLP-1 (glucagon-like peptide-1), which increases insulin secretion after eating, decreases glucagon secretion, slows gastric emptying, and increases the feeling of satiety. This leads to reduced food intake and weight loss.
- Area of application: All three medications are used for weight reduction in adults with overweight or obesity, often in combination with a calorie-reduced diet and increased physical activity.
- Mode of administration: They are administered as injections, with the frequency of administration varying depending on the medication.
Differences between semaglutide, liraglutide, and tirzepatide
Active ingredient structure and additional effects:
- Semaglutide (Wegovy, Ozempic) and liraglutide (Saxenda) are pure GLP-1 receptor agonists. Semaglutide has a longer duration of action, which means it needs to be administered less frequently (once weekly) compared to liraglutide, which is injected daily.
- Tirzepatide (Mounjaro) is a dual agonist that stimulates both the GLP-1 receptor and the GIP receptor (glucose-dependent insulinotropic polypeptide). This dual action can lead to improved efficacy in reducing body weight by activating the GIP receptor in addition to the GLP-1 effect, which further improves insulin secretion and lowers blood sugar levels more effectively.
Effectiveness and side effects of semaglutide, liraglutide, and tirzepatide
- Although all three medications are effective in the treatment of overweight and obesity, they differ in some respects, such as the time it takes for weight loss to occur or which side effects may occur. Side effects can include gastrointestinal complaints such as nausea, vomiting, constipation, and diarrhea.
- In clinical studies, tirzepatide potentially shows higher effectiveness in weight loss compared to pure GLP-1 receptor agonists, which is partly due to the additional effect on the GIP receptor.
In summary, semaglutide, liraglutide, and tirzepatide share the mechanism of GLP-1 receptor agonism, which contributes to weight loss, but they differ in their chemical structure, additional effects, and frequency of administration. The choice of medication depends on individual factors, preferences, and medical recommendations.
All-clear: No link between GLP-1 receptor agonists and thyroid cancer
In June 2023, the EMA (European Medicines Agency) stated that a new study suggests there could be an increased risk of thyroid cancer in people with type 2 diabetes being treated with GLP-1 medications. Further studies have so far shown no causal link: In October 2023, the EMA's safety committee (PRAC) reported, based on the results of a French case-control study, that currently available data do not confirm the recently raised concerns about an increased risk of thyroid cancer from these drugs. After reviewing the existing findings, no direct evidence was found to indicate that the use of glucagon-like peptide-1 receptor agonists (GLP-1), including exenatide, liraglutide, dulaglutide, semaglutide, and lixisenatide, increases the risk of thyroid cancer.
Who is treatment with "weight-loss injections" suitable for?
Contrary to some media reports and the representation on social media platforms, newer weight-loss medications are not designed for people who want to lose a few kilos quickly. They are prescription drugs specifically intended for support in the treatment of severe overweight or obesity.
Weight-loss injections or GLP-1 medications can represent effective support for certain groups of people, but require careful selection and monitoring by medical professionals. It is important that these medications are viewed as a supplement to, and not a replacement for, a healthy diet and sufficient exercise.
Treatment with weight-loss injections is generally suitable for individuals who:
- Have a body mass index (BMI) of 30 or higher (obesity).
- Have a BMI of 27 or higher and simultaneously suffer from weight-related health problems, such as type 2 diabetes, high blood pressure, or dyslipidemia.
- Have difficulty losing significant weight through diet and exercise alone.
- Are willing to combine their lifestyle changes with medical treatment to achieve long-term results.
Although semaglutide, for example, is generally considered well-tolerated, a careful weighing of benefits and potential risks is essential.
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Are GLP-1 medications for obesity treatment also suitable for diabetics?
Yes, GLP-1 (glucagon-like peptide-1) medications are used not only for the treatment of obesity but also for the treatment of diabetes, particularly type 2 diabetes. Some GLP-1 medications, such as liraglutide (used in Saxenda) and semaglutide (used in Ozempic and Wegovy), have approvals for both the treatment of obesity and the treatment of diabetes.
How much can one lose with weight-loss injections?
The extent of weight loss from weight-loss injections can vary and depends on various factors, including individual response to the medications, accompanying diet, physical activity, and general state of health.
With proper therapy for obesity, 30 to 40 kilograms per year are possible, or current studies indicate 15-20% weight loss. In the STEP 1 study on semaglutide, obese non-diabetics on semaglutide plus lifestyle intervention had lost about 14.9% of their weight after just over a year (BMI: –5.5 kg/m2), while the placebo group with only lifestyle intervention, i.e., without GLP-1 medication, only managed about 2.4% (BMI: –0.9 kg/m2). 32% of the participants in the semaglutide group even achieved a weight loss of over 20%, compared to only 1.7% in the placebo group. In the recently published STEP-3 study, it was demonstrated that with an even more intensive diet and exercise program, semaglutide is even more effective. Here, the weight loss was –16%.
How long does treatment with weight-loss injections take?
How long it takes to lose weight with medications like Ozempic, Wegovy, or Saxenda is individual. Typically, it takes a few weeks up to 1 month for the first effects to show.
Basically, the medications are designed to be used long-term in a comprehensive therapy. Current data suggest that there is significant weight regain after discontinuation, and thus for most affected individuals, permanent use is necessary to maintain the reduced body weight. Stopping the medications should also be medically supervised, as it can not only result in a yo-yo effect but also disrupt the body's insulin balance. Therefore, a doctor should always be consulted beforehand. Stopping weight-loss injections: Will the pounds come back?
For some patients, interval therapy could also be an option. However, scientific data on this is still lacking.
How can the yo-yo effect be prevented after treatment with weight-loss injections?
A common concern with weight reduction is the so-called yo-yo effect – the rapid regain of weight after the end of a diet or medical treatment. The good news is that weight-loss medications, especially those based on GLP-1 receptor agonists, aim to bring about long-term changes in eating behavior and metabolism. However, it is important to understand that maintaining a healthy lifestyle, including a balanced diet and regular physical activity, is crucial to avoiding the yo-yo effect. After stopping the medications, patients should work closely with their doctors to develop a plan for sustainable weight maintenance.
What does obesity treatment with weight-loss injections cost?
The costs for obesity treatment with Ozempic, Wegovy, or Saxenda can vary significantly, depending on several factors such as the country in which the treatment is performed, the availability and dosage of the medication, the duration of the therapy, and the patient's insurance coverage. In Germany, cost coverage for weight-reduction medications by statutory health insurance companies is generally restrictive and usually tied to strict indications such as the presence of comorbidities. Private health insurance companies have different regulations that depend on individual contract terms. As a general guideline for the costs of treatment with GLP-1 injections for obesity without insurance coverage, one can calculate several hundred euros per month.
At SoLean, you pay for the weight-loss injection starting from 99 € (depending on the medication and prescribed dose) for the entire weight-loss program including the medication.
Weight-loss injections: A revolutionary method?
Weight-loss injections are often described as revolutionary, as their ability to significantly reduce the feeling of hunger and thus decrease food intake without the patient constantly thinking about food represents a breakthrough in the treatment of overweight and obesity. These medications offer many people realistic hope for successful weight reduction, especially in combination with a healthy diet and regular exercise.
It is possible to buy weight-loss injections online with a valid doctor's prescription or have them prescribed. Online pharmacies and specialized medical service providers offer this service. At SoLean, you can request a prescription after a medical consultation (100% digital) and have the medication delivered directly to your home.
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