Retatrutide Weight Loss Calculator
Estimate your weight loss timeline on Retatrutide using your personal stats and clinical trial data from the NEJM Phase 2 trial. Individual results vary.
How the calculator works
This tool turns the average results from the published Phase 2 Retatrutide trial into a projection shaped by your own numbers. It first estimates your daily energy burn with the Mifflin-St Jeor equation, then models week-by-week weight change from a steady rate of loss plus whatever calorie deficit you set. The outputs are BMI, total daily energy expenditure, the weight you would need to lose to reach your goal, and projected body weight at 12, 24, and 48 weeks. None of this is a prescription. It is a planning estimate, and individual results vary.
Retatrutide arrives as a freeze-dried powder, so it has to be reconstituted before any dose can be measured. Reconstitution means dissolving the powder in bacteriostatic water to reach a known concentration, which is what makes an accurate draw possible. Adding more water lowers the concentration and raises the volume you draw; adding less does the opposite. The total peptide in the vial stays the same either way. If you want to see that concentration math for a specific vial, the peptide reconstitution calculator handles it, and the beginner injection guide walks through the mixing and measuring steps in plain terms.
One common question before mixing is which liquid to use. Bacteriostatic water contains a preservative that keeps a reconstituted vial stable for weeks, while plain sterile water does not, and the difference matters for shelf life. The BAC water vs sterile water FAQ covers that distinction. For the background on what Retatrutide is, how its triple-receptor mechanism differs from single and dual agonists, and what the research reports, read the full Retatrutide guide.
Frequently asked questions
What does this Retatrutide calculator do?
It estimates a weight loss timeline by combining your stats with figures reported in the published Phase 2 Retatrutide trial. You enter your weight, goal weight, height, age, activity, calorie target, and protein level, and it projects body weight at 12, 24, and 48 weeks, your BMI, your daily energy burn (TDEE), and how those numbers shift when a calorie deficit is added on top. The outputs are projections for education, not medical instructions, and individual results vary.
What does reconstitution mean for a peptide like Retatrutide?
Retatrutide ships as a freeze-dried (lyophilized) powder that has to be dissolved in liquid before it can be measured. Reconstitution is that mixing step: adding bacteriostatic water to the vial turns the powder into a solution at a known concentration, which is what lets a dose be drawn accurately. The amount of water you add changes the concentration and the volume you draw, not the total amount of peptide in the vial. Our peptide reconstitution calculator handles that concentration math.
How accurate are the weight loss projections?
They are estimates, not guarantees. The model uses the Mifflin-St Jeor equation for energy burn and the average results reported in the trial, where participants on the highest dose saw a 24.2 percent mean weight loss over 48 weeks. Your real numbers depend on diet, sleep, training, genetics, and consistency, so treat the timeline as a planning reference rather than a promise.
Why does protein intake affect the muscle retention number?
Rapid weight loss can cost lean mass alongside fat. Research on weight loss generally reports that higher protein intake and resistance training help preserve muscle during a calorie deficit. The calculator reflects that pattern by raising the estimated retention figure as your protein level increases. It describes what the research trend shows and does not set a target for you.
Should I follow the titration schedule shown in the results?
The schedule shown reflects the dose ramp used in the published trial and is included for context only. It is not a prescription or a personal protocol. Decisions about whether a compound is appropriate for you, and at what dose, belong with a qualified clinician who knows your history.