Compute the daily calorie deficit to lose X kg in Y weeks, or the time needed for a given deficit. 1 kg of fat ≈ 7700 kcal.
Weekly loss speed
0.63 % / wk → Optimal
To preserve muscle mass, stay between 0.5% and 1% of body weight per week. Above 1.5% increases the risk of sarcopenia and fatigue.
Want to know what to eat with this deficit?
Generate a sample daily menu hitting your target macros.
To lose fat you need a calorie deficit: eat less than you burn. Roughly, 1 kg of body fat equals about 7700 stored kcal.
What's the optimal deficit
The sweet spot is 0.5% to 1% of body weight per week. Slower is boring but sustainable; faster means losing muscle, performance and motivation. For 80 kg that's 400-800 g/week, equivalent to a 440-880 kcal daily deficit.
Why you stall
As you lose weight your metabolism adapts downward (less body mass = lower expenditure). NEAT also drops unconsciously (you move less). Recompute calories every 4-6 weeks or every 3-4 kg lost. Consider 1-2 week 'diet breaks' at maintenance after 6-8 weeks in deficit.
Frequently asked questions
What's a safe deficit?+
0.5-1% of your body weight per week is sustainable. Beyond that you lose a lot of muscle mass and performance drops. For an 80 kg person that's 400-800 g/week, equivalent to 440-880 kcal/day.
Why does my weight loss stall?+
Your metabolism adapts: you lose weight, burn less, and the real deficit shrinks. Recompute calories every 4-6 weeks or every 3-4 kg lost.