Enter your numbers, pick a sustainable weekly pace, and see your projected goal date. Math is based on standard calorie-deficit physiology (about 3,500 kcal per pound of fat).
Use the simple math: weight to lose ÷ weekly pace = weeks needed. The two cards show your projected date at 1 lb/wk (sustainable) and 2 lb/wk (ambitious), the ACSM-recommended bookends for sustainable fat loss. Independent of any medication, adequate protein and resistance training during a deficit are the most consistently studied levers for protecting lean mass.
Sources: Hall, Lancet, 2011 · Donnelly et al., Med Sci Sports Exerc, 2009 (ACSM) · Helms et al., J Int Soc Sports Nutr, 2014The projection uses simple, well-studied energy-balance math: about 3,500 kcal per pound of fat loss. Pick a sustainable weekly pace, and the calculator solves for the date your weight crosses your goal.
Why protein and resistance training matter at any pace, the goal is fat loss, not weight loss. Adequate protein and resistance training during a deficit are the most consistently studied levers for protecting lean mass (Helms et al., 2014; Stiegler & Cunliffe, 2006).
A moderate deficit you can sustain beats an aggressive one you can't.
Roughly 0.7-1.0 g per lb of goal body weight during a deficit supports lean-mass preservation.
2-4 sessions per week is the single strongest signal for keeping what you have.
Short sleep is linked to higher hunger and lower training quality; protect the basics first.
It's a planning model based on standard calorie-deficit math (Hall, Lancet, 2011). Real-world progress varies with adherence, sleep, training, and individual physiology, so treat the projected date as a directional plan rather than a guarantee.
For this calculator: protein at ~1g per pound of target body weight per day, calorie tracking with a moderate deficit (~500/day below maintenance), and resistance training 3-4×/week. This pattern aligns with the ACSM Position Stand on sustainable fat loss (Donnelly et al., 2009). You don't need to be a bodybuilder, you need consistent inputs.
Larger goals just take longer at the same pace. Pair the deficit with adequate protein and resistance training to protect lean mass over a longer timeline. A licensed physician helps calibrate strategy as you progress.
Yes. The model assumes a consistent daily deficit and steady training. Real-world adherence drops and life happens, so a small buffer of 4-8 weeks past the projected date is realistic.
Yes. Strategies that help include consistent adherence, adequate protein and resistance training during the deficit, and quality sleep.
Maintenance is its own phase. Fat loss is easiest to keep when you move from a deficit to maintenance calories gradually and keep protein and resistance training in place. Plan that transition before you reach your goal.
This calculator uses standard calorie-deficit physiology. The flat 3,500-calories-per-pound rule is a useful approximation, but real-world loss slows as your body adapts, so the projected date is an estimate. It is for education only and is not medical advice.
Knowing the goal date is step one. These tools fill in the rest, calories, macros, hormones, and the long-game biological-age impact.
Hand-picked guides on nutrition, plateaus, muscle preservation, and what happens after you hit your goal.
These projections are educational estimates based on calorie-deficit math. Whether any protocol is appropriate for you is determined by a U.S. licensed physician after reviewing your history, labs, and goals.
Take the 60-second quiz. A U.S.-licensed physician reviews your information and builds a plan that fits your goals.
No commitment. A licensed physician decides what is appropriate.
Goal-date projections use the standard energy-balance approximation of about 3,500 kcal per pound of fat loss (Hall, Lancet, 2011). The cards compare nutrition alone (about a 500 kcal per day deficit) with nutrition plus strength training, which adds calorie burn to reach the goal sooner, within the ACSM-recommended sustainable range. This calculator is for informational purposes only and is not medical advice; whether any medication is appropriate for you is determined by a licensed physician.
OPTML offers compounded semaglutide and tirzepatide, prescribed and overseen by U.S.-licensed physicians. Compounded drug products are not approved or evaluated for safety, effectiveness, or quality by the FDA. OPTML is not associated with, endorsed by, or affiliated with the manufacturers of FDA-approved branded weight-loss medications, and does not sell or supply those branded products. Anyone interested in an FDA-approved branded medication should consult a licensed healthcare provider or pharmacist. Individual results vary; no specific result is promised, and weight management requires ongoing medical guidance.
The whole picture in one sitting: who it suits, what the labs decide, what the first year actually looks like. Every clinical claim is cited.
How to protect lean mass while losing weight on a GLP-1.
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