Dr. Lecturer Member Gülen Ecem Kalkan gave important information about GLP-1 and GIP-based drugs, which have become widespread in the treatment of obesity in recent years and are known to the public as "slimming injections". Kalkan emphasized that these drugs were not developed for aesthetic purposes, but for the treatment of obesity, which is a chronic disease, and stated that the use of drugs not supported by lifestyle changes does not provide permanent success.
While there has been a significant transformation in obesity treatment in recent years, drugs known to the public as "slimming injections" have become one of the most talked about health topics. However, this intense interest also brings with it information pollution and unrealistic expectations.
Dr. from Atlas University, Faculty of Health Sciences, Department of Nutrition and Dietetics. Lecturer Member Gülen Ecem Kalkan evaluated the questions about slimming injections in the light of current scientific data.
Slimming injections work by mimicking satiety hormones
Dr. Lecturer Member Gülen Ecem Kalkan stated that most of the drugs known to the public as slimming injections are incretin-based drugs and shared the following information:
"Drugs containing the active ingredient semaglutide and tirzepatide mimic the natural satiety hormones called GLP-1 and GIP, which are secreted from the intestines after a meal. Today, the intestine is considered not only a digestive organ, but also an important endocrine organ that regulates the body's energy balance. While these drugs increase the release of insulin from the pancreas depending on blood sugar, they delay gastric emptying and prolong the feeling of fullness by affecting the appetite centers in the brain. Thus, daily energy intake decreases."
Not everyone can use it, it was not developed for aesthetic purposes
Underlining that these drugs are not suitable for everyone who wants to lose a few kilos, Kalkan said, "The drugs in question were not developed to lose a few kilograms for aesthetic purposes, but for the medical treatment of chronic diseases such as type 2 diabetes and obesity."
According to international guidelines, drugs; Stating that it is recommended to be used in adults who cannot benefit from lifestyle changes, whose body mass index (BMI) is 30 kg/m or above, or whose BMI is above 27 kg/m and who have at least one disease accompanying obesity such as hypertension, dyslipidemia, sleep apnea or cardiovascular disease, Kalkan stated that the treatment must be carried out under the supervision of a physician.
The most common side effects are related to the digestive system
Stating that slimming injections have side effects, as with every medication, Kalkan stated that digestive system complaints such as nausea, vomiting, diarrhea and constipation may be observed, especially in the first weeks of treatment. Kalkan said, "Side effects mostly occur in the first 4-8 weeks and during the dose increase periods. They usually decrease as the body adapts to the drug."
Emphasizing that in some cases such as a certain history of thyroid cancer, severe pancreatitis, type 1 diabetes, pregnancy and breastfeeding, medications should not be used or very close monitoring is required, Kalkan said that suitability should be evaluated by a physician.
Proper nutrition helps alleviate side effects
Stating that the diet is an integral part of the treatment, Kalkan stated that eating small portions, eating slowly, and avoiding fatty and fried foods, especially when increasing the dose, can reduce nausea.
Increasing fluid consumption and gradually increasing fiber intake in individuals experiencing constipation; Stating that it may be beneficial to limit fatty and very spicy foods in case of diarrhea, Kalkan drew attention to the importance of consuming enough fluids throughout the day.
It's not the number on the scale, it's the content of the weight lost that matters
Dr. Lecturer Member Gülen Ecem Kalkan stated that the weight lost with medications does not consist only of fat tissue and said, "What is important in successful weight loss is not only the decrease in the scale. What is really important is how much of the weight lost comes from fat and how much comes from muscle tissue."
Stating that protein intake decreases with the decrease in appetite, Kalkan said that this may increase muscle loss and said, "In the body composition analysis of the STEP 1 activity with Semaglutide, it was shown that approximately 35-40 percent of the weight lost came from lean tissue, that is, tissues including muscle. The loss of muscle tissue may reduce the basal metabolic rate and facilitate weight regain in the future."
Weight regain may occur when the drug is stopped
Kalkan stated that scientific activities have revealed that weight regain is common after stopping the drug and said, "In the STEP 4 and SURMOUNT-4 activities, it was observed that the weight loss continued in the individuals who continued the medication, while there was a significant weight regain in the groups that stopped the treatment. This gain is the expected result of a biological process, not a lack of willpower; when people stop taking the drug, they both feel more hunger and spend less energy. This picture once again reveals that obesity is a chronic and recurring disease."
Muscle loss poses a significant risk in the long term
Stating that repeated cycles of weight loss and regain can negatively affect body composition over time, Kalkan drew attention to the risk of sarcopenic obesity, especially in older ages.
Pointing out that the real critical point occurs in the long term, Kalkan warned: "When the drug is stopped, the weight regained consists mostly of fat tissue; the lost muscle is not regained as easily. Therefore, repetitive loss-recovery cycles may lead to an increase in the fat rate in the body and a decline in the muscle rate over time."
Dr. Lecturer Member Gülen Ecem Kalkan said:
"Especially at advanced ages and in frequently recurring cycles, this situation may pave the way for 'Sarcopenic obesity', where muscle mass and strength decrease, but the fat content is high. In an exercise performed in women with obesity, 0.26 kg of lean tissue was lost for every 1 kg of fat lost during weight loss, while only 0.12 kg of lean tissue was regained for every 1 kg of fat regained in the following period.
In short, muscle tissue is easy to lose, but difficult to regain; This makes it even more important to maintain muscle mass from the beginning. For this reason, the process should be planned from the very beginning by a dietitian with an individual-specific medical nutrition treatment; It should be followed regularly with a team approach carried out by the physician and dietitian. "In addition, adding resistance training to the treatment under the supervision of a physiotherapist makes a significant contribution to the preservation of muscle mass."
Protein intake and resistance exercise are indispensable for treatment
Dr. Lecturer Member Gülen Ecem Kalkan stated that adequate protein intake and regular resistance exercise are critical to prevent muscle loss in individuals receiving GLP-1 treatment and said, "Not only energy but also carbohydrate, protein, vitamin and mineral intake may decrease due to decreased appetite. Therefore, the nutrition plan must be prepared individually, and when necessary, regular monitoring should be done in terms of micronutrients such as vitamin B12, iron, zinc, vitamin D, calcium and magnesium."
"Medications are not a substitute for lifestyle change"
Stating that one of the biggest mistakes made during the treatment process is excessively low energy intake, Kalkan stated that skipping meals can increase muscle loss. Kalkan said, "Making appetite control available to people is an important opportunity to make healthy eating habits permanent. The most effective way to limit the weight regain seen when the drug is stopped is the lifestyle changes made during this period. As a matter of fact, in the STEP 3 activity, semaglutide provided approximately 16 percent weight loss with an intensive lifestyle support carried out by a dietitian, while this rate remained at 5.7 percent in the group receiving lifestyle support only. Therefore, instead of malnutrition during the period when the drugs are used, a sustainable and balanced diet is achieved." "Order should be established," he said.
Kalkan reminded that according to TÜİK's 2025 Turkey Health Survey data, the prevalence of obesity in individuals aged 15 and over increased to 21.8 percent, and this rate was reported as 24.8 percent for women and 18.7 percent for men.
Dr. Lecturer Member Gülen Ecem Kalkan concluded her words with the following evaluation:
"Neither rejecting these drugs completely nor seeing them as a solution is the right approach. Modern medicine offers very effective drug options in the treatment of obesity. However, these treatments provide meaningful and sustainable results when applied together with nutrition patterns, physical activity and behavioral changes. Slimming injections are not a solution on their own, but an important part of a properly planned multidisciplinary treatment." - ISTANBUL