GLP-1 weight loss results: what the trials actually show

About this data

The weight loss data on this page comes from published, peer-reviewed clinical trials — primarily the STEP program (semaglutide), SURMOUNT program (tirzepatide), and SCALE program (liraglutide). These trials were conducted with specific patient populations and included lifestyle interventions (dietary counseling and exercise recommendations) alongside medication.

Individual results may differ substantially from these averages. Factors such as starting weight, diet quality, physical activity, medication adherence, and individual biology all influence outcomes. This page presents data for educational purposes and should not be used to set expectations for your own treatment. For a broader overview of these medications, see our What Are GLP-1 Medications? guide.

Results by medication

Detailed clinical trial data for each major GLP-1 medication studied for weight loss.

Semaglutide (Wegovy®) — STEP trials

The STEP (Semaglutide Treatment Effect in People with obesity) program is a series of clinical trials evaluating semaglutide 2.4mg for chronic weight management.

14.9% average body weight loss (STEP 1 primary endpoint)

STEP 1 (Primary Weight Loss Trial)

• Participants: 1,961 adults with BMI 30+ (or 27+ with weight-related conditions)
• Duration: 68 weeks
• Average weight loss: 14.9% of body weight (vs. 2.4% with placebo)
• Notable: 86.4% of participants lost at least 5% of body weight
• Source: Wilding et al., New England Journal of Medicine (2021)

STEP 2 (Type 2 Diabetes Population)

• Participants: 1,210 adults with type 2 diabetes and BMI 27+
• Average weight loss: 9.6% of body weight (vs. 3.4% placebo)
• Note: Weight loss is typically lower in populations with type 2 diabetes

Tirzepatide (Zepbound®) — SURMOUNT trials

The SURMOUNT program evaluated tirzepatide (a dual GIP/GLP-1 receptor agonist) for chronic weight management across multiple dose levels.

20.9% average body weight loss (SURMOUNT-1, 15mg dose)

SURMOUNT-1 (Primary Weight Loss Trial)

• Participants: 2,539 adults with BMI 30+ (or 27+ with weight-related conditions)
• Duration: 72 weeks
• Average weight loss (15mg dose): 20.9% of body weight (vs. 3.1% placebo)
• Average weight loss (10mg dose): 19.5% of body weight
• Average weight loss (5mg dose): 15.0% of body weight
• Source: Jastreboff et al., New England Journal of Medicine (2022)

SURMOUNT-2 (Type 2 Diabetes Population)

• Participants: 938 adults with type 2 diabetes and BMI 27+
• Average weight loss (15mg): 14.7% of body weight
• Note: Weight loss is typically lower in populations with type 2 diabetes

Liraglutide (Saxenda®) — SCALE trial

The SCALE (Satiety and Clinical Adiposity — Liraglutide Evidence) program studied liraglutide 3.0mg for chronic weight management. Liraglutide was one of the earlier GLP-1 receptor agonists approved for weight loss.

8.0% average body weight loss (SCALE, 3.0mg dose)

SCALE Obesity and Prediabetes Trial

• Participants: 3,731 adults with BMI 30+ (or 27+ with weight-related conditions)
• Duration: 56 weeks
• Average weight loss: 8.0% of body weight (vs. 2.6% placebo)
• Notable: 63.2% of participants lost at least 5% of body weight
• Administration: Daily injection (vs. weekly for semaglutide and tirzepatide)
• Source: Pi-Sunyer et al., New England Journal of Medicine (2015)

Weight loss timeline

Based on aggregate clinical trial data, here is what the research shows about the typical pace of weight loss on GLP-1 medications. Individual timelines vary significantly.

1. 1
   Months 1–3: Initial response

   The most rapid phase of weight loss in clinical trials. Dosage is typically being titrated upward during this period. Participants begin experiencing reduced appetite and initial weight changes.
2. 2
   Months 3–6: Continued loss

   Weight loss continues at a steady pace for most participants. Many reach their target dose during this phase. Clinical trials show consistent downward trends in body weight through month 6.
3. 3
   Months 6–12: Approaching plateau

   The rate of weight loss begins to slow for most participants. The body adapts to the lower caloric intake and reduced weight. Most clinical trials show the majority of weight loss occurring by this point.
4. 4
   After 12 months: Maintenance phase

   Weight typically stabilizes in what researchers call a "weight plateau." Clinical trials show weight maintenance (rather than continued loss) for most participants who continue medication.

Factors that influence your results

Clinical trials and published research have identified several factors that influence weight loss outcomes on GLP-1 medications. Understanding these can help you have more productive conversations with your healthcare provider.

Starting weight & BMI

Clinical trials suggest that individuals with higher starting BMI tend to lose a greater absolute amount of weight, though the percentage of body weight lost may vary. The body's metabolic response to medication is influenced by baseline weight and body composition.

Diet & nutrition quality

All major GLP-1 clinical trials included dietary counseling as part of the intervention. Nutrition quality — particularly adequate protein intake — influences both the amount and composition of weight lost. Research shows that adequate protein intake helps preserve lean muscle mass during weight loss.

Physical activity

Exercise has been shown to enhance weight loss outcomes on GLP-1 medications. A study published in Nature Medicine found that combining structured exercise with GLP-1 medication resulted in approximately 24.5% total body weight loss — compared to 18.2% with medication alone.

Medication adherence

Consistent use of GLP-1 medications as prescribed is associated with better outcomes. Research shows that approximately 50% of patients discontinue GLP-1 medication within 12 months, and those who maintain consistent adherence tend to achieve and sustain greater weight loss.

Additional factors that may influence results include genetics, sleep quality, stress levels, metabolic health, insulin sensitivity, and concurrent medications. Discuss all of these factors with your healthcare provider for personalized guidance.

Track your progress with Dose AI

While clinical trials provide population-level averages, your journey is individual. Dose AI helps you track the factors that research shows matter most — weight trends, nutrition, medication adherence, and symptoms. Dose AI is a tracking tool, not a medical device.

Key numbers from the research

Published clinical trial and research data.

Dose AI is a tracking and information tool, not a medical device. It does not predict weight loss outcomes. Always consult your healthcare provider for medical advice about your GLP-1 medication.