The 3,500 Calorie Rule (Wishnofsky Law)
The classical rule of thumb stating that a cumulative 3,500 kcal deficit produces one pound of body fat loss.
Clinical & Bioenergetic Overview
Published in 1958 by Dr. Max Wishnofsky, this calculation assumes that 1 pound (454 grams) of human adipose tissue is approximately 87% pure lipid fat, containing ~395 grams of triglycerides at 9 kcal/gram, yielding ~3,555 kcal. While accurate in a short-term closed chemical system, it fails to predict long-term weight loss due to dynamic metabolic adaptation and shifting body composition.
Mathematical Formula & Calculation
Real-World Worked Example
A daily deficit of 500 kcal yields: (500 × 7) = 3,500 kcal weekly deficit = 1.0 lb predicted fat loss per week.
Why It Matters for Dieting
Useful for short-term planning (first 4-6 weeks), but must be adjusted as weight decreases and metabolism adapts.
Frequent Mistakes
Expecting weight loss to remain strictly linear indefinitely. In reality, as you lose weight, TDEE drops and the deficit narrows unless adjustments are made.
Simulate Weight Timeline
Use our dynamic simulator to project plateau-adjusted fat loss milestones.
Related Bioenergetic Terms
A state where total energy expenditure exceeds total energy intake, prompting the mobilization of endogenous fuel reserves.
The physiological decline in resting and non-resting energy expenditure beyond what is predicted by the loss of body mass.