What is the percent reduction in Body Mass Index (BMI) with GLP-1 (Glucagon-like peptide-1) weight loss medications, such as liraglutide (Victoza) and semaglutide (Ozempic)?

From the Guidelines

GLP-1 medications, such as semaglutide and liraglutide, can produce a significant reduction in Body Mass Index (BMI), with average reductions ranging from 5-15% from baseline, depending on the specific medication and dosage. The most recent and highest quality study, published in 2023 in the journal JAMA 1, reported that semaglutide achieved a mean weight loss of 14.9% at 68 weeks, while liraglutide achieved a mean weight loss of 8.0% at 56 weeks. Another study published in 2024 in the journal Anaesthesia 1 also reported that semaglutide resulted in a mean weight loss of 14.9% in patients who were non-diabetic, overweight or obese. Key points to consider when using GLP-1 medications for weight loss include:

• Semaglutide generally achieves greater weight loss than liraglutide
• Maximum benefits usually require gradual dose escalation over several weeks to minimize gastrointestinal side effects
• Weight loss typically continues for 6-12 months before plateauing
• For optimal results, these medications should be combined with lifestyle modifications including caloric restriction and increased physical activity
• Individual responses vary significantly, with some patients experiencing greater or lesser BMI reductions than the averages reported in clinical trials. It's also important to note that long-term use of GLP-1 medications is necessary to maintain weight loss, as significant weight regain can occur after cessation of treatment, as reported in the STEP trials 1.

From the FDA Drug Label

Both treatment groups had a mean decrease from baseline in body weight of approximately 3 kg

The percent reduction in Body Mass Index (BMI) with GLP-1 weight loss medications, such as liraglutide, is not directly provided in the given drug labels. However, a mean decrease from baseline in body weight of approximately 3 kg is mentioned in one of the trials.

• To calculate the percent reduction in BMI, we would need the initial and final BMI values, which are not provided in the labels.
• The labels do provide the mean BMI for various trials, but they do not give the percent reduction in BMI.
• Therefore, we cannot determine the percent reduction in BMI with GLP-1 weight loss medications based on the given information 2, 2, 2.

From the Research

GLP-1 Weight Loss Medications and BMI Reduction

• The effect of GLP-1 receptor agonists on weight loss has been studied in several clinical trials, with semaglutide and liraglutide being two of the most commonly used medications for this purpose 3, 4.
• A systematic review of 23 randomized controlled trials (RCTs) found that semaglutide 2.4mg resulted in the greatest weight loss, with a mean reduction of -12.47 kg, followed by liraglutide 3.0mg (-5.24 kg), semaglutide 1.0mg (-3.74 kg), and liraglutide 1.8mg (-3.29 kg) 5.
• Another study found that semaglutide 2.4mg weekly resulted in an average weight loss of 15% at 1 year, which is significantly more than the weight loss achieved with other medications approved for chronic weight management 6.
• A network meta-analysis of RCTs found that tirzepatide, a new GLP-1 receptor agonist, resulted in more weight loss than semaglutide 2.4mg, daily semaglutide 0.4mg, or liraglutide 3mg, with comparable safety profiles 7.

Percent Reduction in BMI

• While the exact percent reduction in BMI is not consistently reported across studies, the weight loss achieved with GLP-1 receptor agonists can be used to estimate the reduction in BMI.
• Assuming an average weight loss of 15% at 1 year with semaglutide 2.4mg weekly, as reported in one study 6, this would correspond to a significant reduction in BMI.
• However, the exact percent reduction in BMI would depend on the individual's initial weight and height, as well as the specific medication and dosage used.

Comparison of GLP-1 Weight Loss Medications

• The available evidence suggests that semaglutide 2.4mg and tirzepatide may be more effective than liraglutide 3mg for weight loss, with semaglutide 2.4mg resulting in the greatest weight loss in some studies 5, 7.
• However, the safety profiles of these medications are also important to consider, with gastrointestinal adverse events being a common side effect of GLP-1 receptor agonists 7.