GLP-1 Weight Loss Injections Show Significant Results in Clinical Studies

Clinical studies have demonstrated significant weight loss results from GLP-1 receptor agonist medications including semaglutide and tirzepatide when combined with lifestyle modifications. A recent study of 1,961 people found that in individuals with a BMI over 30 who did not have diabetes, GLP-1 injections combined with exercise resulted in a mean decrease in body weight of 14.9% over 68 weeks, while the placebo group saw only a 2.4% mean decrease in weight.

Long-term data from the SELECT trial showed sustained effects, with patients treated with semaglutide experiencing continued weight loss through 65 weeks and effects maintained for up to four years. At 208 weeks, semaglutide was associated with a mean weight reduction of 10.2%, waist circumference decrease of 7.7 cm, and waist-to-height ratio reduction of 6.9% compared with placebo, which showed 1.5%, 1.3 cm, and 1.0% respectively. Clinically meaningful weight loss was observed across sexes, races, body sizes, and regions.

A second study found that when combined with behavioral therapy and incorporating a low-calorie diet into meal plans, GLP-1 provided even more significant weight loss.

Semaglutide is a GLP-1 receptor agonist for weight loss that mimics a natural hormone called glucagon-like peptide-1. This hormone regulates appetite and blood sugar levels. The medication reduces hunger, slows digestion, and increases fullness. Clinical trials have shown significant weight loss in adults using semaglutide compared to placebo groups. Many patients achieve substantial weight loss, often around 15% of their body weight over approximately 68 weeks.

Tirzepatide acts on both GLP-1 and GIP receptors. It improves insulin response and reduces appetite signals. Research suggests tirzepatide may produce even greater weight loss results in some individuals. It helps regulate blood glucose and reduces calorie intake by controlling hunger.

GLP-1 medications function as glucagon-like peptide-1 receptor agonists, hormones that regulate appetite, food intake, and glucose metabolism. When a person eats, GLP-1 hormone signals the brain that the stomach feels full. The medication also slows gastric emptying, which means food stays in the stomach longer. It increases insulin release when blood sugar rises and reduces glucagon production, helping to stabilize blood sugar levels. Stable blood sugar reduces cravings and sudden hunger spikes.

By activating GLP-1 receptors in the brain and gastrointestinal tract, these medications decrease hunger sensations, delay gastric emptying, and increase feelings of fullness, which typically leads to reduced food intake and weight loss. By lowering appetite and improving insulin response, users naturally eat fewer calories, and over time, this calorie reduction leads to steady weight loss.

GLP-1 is often prescribed to individuals who have a Body Mass Index of 30 or higher, or individuals with a BMI of 27 or higher that is accompanied by high blood pressure, type 2 diabetes, high cholesterol, or other health conditions that can make weight loss difficult. Eligibility typically includes adults with at least one weight-related health condition such as type 2 diabetes, hypertension, or dyslipidemia.

The injections only need to be given once per week as a subcutaneous injection. The dosage is typically increased over time as the weeks progress. It often is not until 4 or more weeks on a dose of 25 units or higher that patients will start to see a decline in weight. Most individuals begin to notice weight loss between 4 to 6 weeks after beginning the injections, though it is possible that some individuals might not notice weight loss until close to 6 weeks, and results will vary from patient to patient.

The most common side effects include nausea, vomiting, diarrhea, constipation, and mild stomach discomfort. These symptoms usually appear during the early stages of treatment or when the dosage increases. Potential side effects can also include headache, fatigue, stomach pain, dizziness, changes in mood, heartburn, and bloating. While rare, more severe side effects can include pancreatitis, allergic reactions, kidney damage, and gallstones.

Long-term studies confirm sustained benefits for many patients, including improvements in cardiometabolic risk factors such as blood pressure, lipid profiles, and glycemic control. The injections offer benefits to qualified candidates including significantly reducing weight when combined with changes in diet and exercise, providing consistent safe weight loss over an extended period of time, and diminished risk of heart and cardiovascular disease upon achieving a healthy weight.