Many people begin their GLP-1 journey with unrealistic expectations, leading to discouragement and the feeling of failure. This can cause individuals to second-guess themselves and ultimately quit. This article aims to provide a realistic framework for understanding expected weight loss on GLP-1 medications, based on clinical trial data.
Introducing the 20% Rule
The "20% Rule" is a guideline for estimating realistic weight loss over a year on GLP-1 medications. This rule is based on data from clinical trials, not just a guess. Understanding this rule can help set appropriate expectations, prevent discouragement, and promote consistent progress. The key is to remember that this is a guide, and individual results may vary.
The Data Behind the Rule: Clinical Trial Evidence
The 20% rule is grounded in data from major GLP-1 clinical trials. The data your doctor uses is also based on these trials.
Surmount One Trial (Terzepatide)
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This 72-week study (approximately 1.5 years) focused on Terzepatide (Mounjaro, Zepbound).
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Results:
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5mg dose: Average of 15% body weight loss.
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10mg dose: Average of 19.5% body weight loss.
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15mg dose: Average of 20.9% body weight loss.
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It's important to note that the highest weight loss (around 20%) was achieved on the highest dose, over a significant period, and with structured support. For most people, a realistic goal is between 15% and 20% weight loss over a year, assuming consistent use and support.
STEP Trial (Semaglutide)
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This study lasted 68 weeks (over a year) and investigated semaglutide.
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Participants experienced an average weight loss of 14.9% of their starting weight.
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This trial also included nutrition support, movement plans, regular check-ins, structure, and accountability, not just the medication alone.
Key Takeaways from the Trials
- People were losing between 15% and 20% of their body weight, with the help of nutrition, movement plans and a lot of accountability
Applying the 20% Rule to Your Weight Loss Journey
Now that the evidence is provided, lets dive into the math behind it.
Calculating Your Expected Weight Loss
- Determine Your Current Weight: Use your weight today, not your starting weight.
- Calculate 20% of Your Current Weight: Multiply your current weight by 0.20 (20%). The resulting number is the expected weight loss over the next year.
- Calculate Monthly Average: Divide the yearly weight loss by 12 to find your average monthly weight loss.
- Calculate Weekly Average (Optional): Divide the monthly average by 4 to get an estimated weekly weight loss.
Examples:
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Example 1: If you currently weigh 258 pounds, your projected yearly weight loss is 51 pounds (258 x 0.20 = 51.6). This translates to approximately 4.3 pounds per month (51.6 / 12 = 4.3).
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Example 2: If you currently weigh 212 pounds, your projected yearly weight loss is 42.4 pounds (212 x 0.20 = 42.4). That calculates to about 3.5 pounds per month (42.4 / 12 = 3.5).
Why Focus on Averages?
Weight loss is rarely linear. The scale will fluctuate. Focusing on monthly or even 6-month averages provides a more accurate picture of progress and prevents unnecessary discouragement from weekly variations.
Addressing Lower Starting Weights
Individuals starting at lower weights often experience slower initial weight loss. This is normal and expected. In these cases, it may be more realistic to aim for 15% to 20% weight loss over the year, rather than strictly adhering to the 20% rule.
- Example: If you currently weigh 180 pounds, a 20% target is 36 pounds lost in a year, or 3 pounds lost per month.
If you start at a lower weight and you have only lost six pounds after three months, that is completely normal.
The Importance of Realistic Expectations and Sustainability
The 20% rule is not a guarantee, but it provides a realistic and data-driven framework for setting expectations. Remember that slow and steady weight loss is still progress. By focusing on long-term averages and celebrating even small victories, you can stay motivated and achieve sustainable results. The goal is not to impress anyone, but to improve your health and well-being.