Turning a weekly goal into a daily calorie adjustment
1kg of body fat holds roughly 7,700 kcal. A goal of losing 0.5kg a week means a total weekly deficit of 0.5 × 7,700 = 3,850 kcal, spread evenly across 7 days: 3,850 ÷ 7 = 550 kcal/day.
A worked deficit example
For an 80kg, 170cm, 30-year-old man, moderately active, maintenance calories (TDEE) come to 2,662 kcal/day. Subtracting the 550 kcal/day deficit for a 0.5kg/week loss goal gives a daily target of 2,112 kcal.
The same idea in reverse, for a surplus
For the same person, aiming for a 0.25kg/week gain instead: that's a smaller daily adjustment, 275 kcal/day, added to the same 2,662 kcal maintenance figure, for a target of 2,937 kcal/day.
Why both targets start from the exact same number
Both the deficit and surplus targets used the identical 2,662 kcal maintenance figure as their starting point — only the direction and size of the adjustment differ. This shared foundation is explored directly in the companion article on why deficit and surplus calculations are really the same calculation, applied in opposite directions.