Energy calculator
GLP-1 Calorie Needs Calculator
Estimate resting and maintenance energy needs, then use the result as context—not a command to eat as little as possible.
Estimate your current energy needs
2,124 kcal / day
Treat the lower range as a discussion point, not an instruction. Energy equations can be wrong for an individual and may overestimate needs as body weight changes.
How the estimate works
Mifflin-St Jeor estimates resting energy from weight, height, age, and one of two sex-based constants. The calculator multiplies that result by an activity factor. The displayed lower range is 10–20% below estimated maintenance and is included only as a conservative discussion range.
Precision has limits
Prediction equations can miss measured resting energy by more than 10% for an individual, and accuracy can shift during weight loss. Your multi-week trend is the calibration signal. Indirect calorimetry is the clinical measurement option when precision is important.
Protect nutrition quality
A smaller food budget makes nutrient density more important. Plan protein first, include fiber-rich foods you tolerate, and use a nutritionally complete shake only when it solves a real intake or convenience problem. Supplements should not disguise chronically inadequate food intake.
Straight answers
Frequently asked questions
How many calories should I eat on a GLP-1?
There is no universal GLP-1 calorie target. Needs depend on body size, age, activity, health, and goals. The estimate can help frame a conversation with a registered dietitian, but it should not override hunger, symptoms, labs, or a clinician-designed plan.
What is Mifflin-St Jeor?
Mifflin-St Jeor is a commonly used equation that estimates resting energy expenditure from weight, height, age, and a sex-based constant. An activity factor then estimates maintenance needs. It is convenient but can be meaningfully wrong for an individual.
Why does the estimate change during weight loss?
Body weight and composition change, and energy expenditure can adapt during a weight-loss intervention. Recalculate periodically and use real weight, energy, and performance trends to calibrate the estimate with a professional.
Should I eat less if my appetite is already very low?
Do not chase a larger deficit when intake is already difficult. Persistent inability to meet basic nutrition or fluid needs, weakness, vomiting, or unexpectedly rapid loss should be discussed with your care team.
Sources and method
Formula choices and health context were checked against the sources below in July 2026. Estimates are rounded so they stay practical.