Data Source & Methodology
AuthoritativeDataSource: Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247. PubMed. “Human Energy Requirements.” FAO/WHO/UNU Expert Consultation, 2001 (activity factors). Report PDF. Guidance on safe weight-loss pace from the U.S. CDC. CDC. Energy content of weight loss discussed by Heymsfield et al. and Thomas et al. (2012; 2014).
Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.
The Formula Explained
Resting Energy (REE), Mifflin–St Jeor:
Male: \\(\\text{REE} = 10\\,w + 6.25\\,h - 5\\,a + 5\\) Female: \\(\\text{REE} = 10\\,w + 6.25\\,h - 5\\,a - 161\\)
where \\(w\\) is weight (kg), \\(h\\) height (cm), \\(a\\) age (y).
TDEE: \\(\\text{TDEE} = \\text{REE} \\times AF\\) (activity factor 1.2–1.9).
Daily deficit: \\(\\Delta = \\text{TDEE} - \\text{intake}\\). Weekly loss (kg): \\(\\Delta_\\text{week}/7700\\).
Time to goal (weeks): \\(\\dfrac{w - w_{\\text{target}}}{\\Delta_\\text{week}/7700}\\) if \\(\\Delta>0\\).
Glossary of Variables
- Sex: selects Mifflin–St Jeor constants.
- Age (a): age in years.
- Height (h): centimeters (or feet/inches).
- Weight (w): kilograms (or pounds).
- Activity factor (AF): multiplier estimating total daily expenditure.
- REE: resting energy expenditure.
- TDEE: total daily energy expenditure = maintenance.
- Deficit (Δ): maintenance minus intake (kcal/day).
How It Works: A Step-by-Step Example
Inputs: Male, 35 y, 175 cm, 75 kg, Moderate (AF = 1.55), planned intake 2,000 kcal/day.
- REE = 10×75 + 6.25×175 − 5×35 + 5 = 1,679 kcal/day.
- TDEE = 1,679 × 1.55 ≈ 2,603 kcal/day.
- Deficit = 2,603 − 2,000 = 603 kcal/day.
- Projected weekly loss ≈ (603 × 7) / 7,700 ≈ 0.55 kg/week.
Frequently Asked Questions
Is 1,200 kcal/day safe?
For many adults, consistently eating <1,200 kcal/day can be unsustainable and risky. Aim for a moderate deficit and seek clinical guidance if unsure. CDC suggests ~0.5–2 lb/week as a sustainable pace.
Which activity factor should I pick?
Choose the description that best matches your routine (e.g., “Moderate” if you exercise 3–5 days/week). You can always fine-tune later.
Why don’t results match reality?
Fluid shifts, glycogen changes, menstrual cycle, meds (e.g., GLP-1), and adaptive thermogenesis can obscure short-term trends. Track averages over weeks.
Can I gain muscle in a deficit?
Possible for beginners or with high protein/resistance training, but building significant muscle is easier at maintenance/slight surplus.
Does this replace medical advice?
No. It’s an educational tool, not a diagnostic device. Consult a clinician for personalized recommendations.
Tool developed by Ugo Candido. Content reviewed by the CalcDomain Editorial Board.
Last accuracy review: