Smart Fitness Calculator
How It's Calculated
Basal Metabolic Rate (BMR)
We use the Mifflin-St Jeor Equation, which is considered the most accurate for non-athlete adults:
Men: BMR = (10 × weight) + (6.25 × height) - (5 × age) + 5
Women: BMR = (10 × weight) + (6.25 × height) - (5 × age) - 161
Source: Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990
Activity Multipliers
Daily calorie needs are calculated by multiplying BMR by an activity factor:
- • Sedentary (× 1.2): Based on WHO/FAO/UNU standards for minimal movement
- • Lightly Active (× 1.375): Validated by the Institute of Medicine
- • Moderately Active (× 1.55): Supported by ACSM guidelines
- • Very Active (× 1.725): Based on research in endurance athletes
- • Athlete (× 1.9): Derived from studies of professional athletes
Weight Change Calculations
Weight change calculations are based on validated energy equivalents:
- • 1 kg of body weight = 7,700 calories
- • 1 lb of body weight = 3,500 calories
Source: Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011
Important Notes
- • These calculations provide estimates and may need adjustment based on individual response
- • Factors like sleep, stress, and medical conditions can affect actual calorie needs
- • Weight changes greater than 1% of body weight per week are generally not recommended
- • Consider consulting a healthcare provider before starting any weight change program
Additional References:
- • American College of Sports Medicine Position Stand (2016)
- • International Society of Sports Nutrition Guidelines (2023)
- • Academy of Nutrition and Dietetics Evidence Analysis Library
- • WHO Technical Report Series 935: Protein and Amino Acid Requirements