The deficit that actually works
Eat enough to lose fat without losing the plot.
Results update as you type 🥑
Choosing a sustainable deficit
A calorie deficit means eating below the calories you burn (your TDEE). About 7,700 kcal roughly equals one kilogram of body fat, so a 500 kcal daily deficit projects to about 0.5 kg per week.
Bigger is not better. Aggressive deficits bring hunger, fatigue, muscle loss and rebound. A 15–20% deficit is the sweet spot for most people — fast enough to progress, gentle enough to sustain and protect muscle with enough protein.
As you lose weight your TDEE falls, so the same intake becomes a smaller deficit. Recalculate every few kilograms and keep protein high.
Common questions
How big should my deficit be?
For most people 15–20% below TDEE. That targets roughly 0.5 kg per week while protecting muscle and adherence.
How fast can I safely lose weight?
About 0.5–1% of bodyweight per week is a sustainable, muscle-sparing rate for most people.
Why has my weight loss stalled?
A lighter body burns fewer calories, so your old deficit may now be maintenance. Recalculate and adjust.
Is my data stored?
No. Everything is calculated in your browser. Nothing is sent to a server or saved.
Sources & references
- Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” J Am Diet Assoc. 2005;105(5):775–789.
This calculator provides estimates for general educational use and is not medical advice. Consult a qualified professional before making significant dietary changes.