About

Most calculators simply subtract 500 calories and hope for the best. This tool works backwards: you tell it when you need to be at your goal weight, and it calculates the mathematical daily deficit required to get there.

It integrates the 3500-calorie rule (1 lb of fat ≈ 3500 kcal) alongside safety thresholds. If your target date requires a dangerous caloric restriction (below BMR), the system will flag it, ensuring your weight loss plan remains sustainable and metabolic damage is avoided.

Formulas

The core logic determines the total caloric gap required and divides it by the time remaining.

TotalDeficit = (Current − Goal) × 7700

This is then annualized to a daily requirement:

DailyDeficit = TotalDeficitDaysRemaining

The final Daily Intake is constrained by safety floors:

TargetCal = TDEE − DailyDeficit

Reference Data

Variable	Standard Value	Notes
Fat Energy Density	~3500 kcal / lb	approx 7700 kcal / kg.
Safe Loss Rate	0.5% - 1.0% Bodyweight/Week	Faster rates risk muscle loss.
Protein Sparing	1.8g - 2.2g / kg	High protein prevents muscle catabolism in deficit.
Min Daily Calories (Men)	1500 kcal	Absolute floor for micronutrient sufficiency.
Min Daily Calories (Women)	1200 kcal	Absolute floor for micronutrient sufficiency.
TEF (Thermic Effect)	~10% of Intake	Energy burned digesting food.
NEAT	Varies (up to 15% TDEE)	Non-exercise movement (fidgeting, walking).

Frequently Asked Questions

This means the deficit required to hit your date is too large (likely starving yourself). Extend your target date or accept a smaller weight loss goal.

As you lose weight, your BMR decreases because a smaller body requires less energy. You must recalculate your macros every 5-10 lbs lost.

Yes. A hard deadline (like a wedding) often motivates adherence, but biology has limits. This tool bridges the gap between motivation and biological reality.

Technically yes for weight loss (CICO), but spreading protein intake throughout the day is better for preserving muscle mass while in a deficit.