Question 1

What is TDEE and how is it calculated?

Accepted Answer

TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day — including your Basal Metabolic Rate (BMR) and all physical activity. It is calculated by multiplying your BMR by a Physical Activity Level (PAL) factor: Sedentary ×1.2, Lightly Active ×1.375, Moderately Active ×1.55, Very Active ×1.725, Extra Active ×1.9. The Mifflin-St Jeor formula is the most widely validated method for estimating BMR in non-obese adults.

Question 2

Which BMR formula is most accurate — Mifflin-St Jeor or Harris-Benedict?

Accepted Answer

Mifflin-St Jeor (2005) is the current gold standard recommended by the Academy of Nutrition and Dietetics (AND). A 2005 systematic review by Frankenfield et al. found Mifflin-St Jeor was accurate within ±10% for 82% of non-obese adults, outperforming both the original Harris-Benedict (1919) and the revised Roza & Shizgal (1984) version. Harris-Benedict tends to over-predict BMR by 5–15% in older adults and women. For individuals who know their body fat percentage, Katch-McArdle is often more accurate than either formula.

Question 3

How does the Weight Goal Planner calculate my timeline?

Accepted Answer

The Weight Goal Planner estimates timeline using the energy balance principle: 1 kg of body fat ≈ 7700 kcal. Weekly weight change = (daily calorie adjustment × 7) ÷ 7700. For example, a daily deficit of 500 kcal yields approximately 500 × 7 ÷ 7700 = 0.45 kg/week. This assumes fat loss only — in practice, initial weight loss includes water weight, and lean mass losses slow the rate. Re-calculate your TDEE every 4–6 weeks as your body weight changes.

Question 4

What are the IOM AMDR macronutrient distribution ranges?

Accepted Answer

The IOM (Institute of Medicine) Acceptable Macronutrient Distribution Ranges (AMDR) from the 2002/2005 Dietary Reference Intakes define healthy macro percentages of total calories: Protein: 10–35%; Carbohydrates: 45–65%; Fat: 20–35%. These ranges are designed to reduce chronic disease risk while meeting micronutrient needs. Athletes and those in caloric deficits may benefit from higher protein (1.6–2.2 g/kg body weight) per ACSM/ISSN position stands.

Question 5

When should I use the Katch-McArdle formula instead of Mifflin-St Jeor?

Accepted Answer

Use Katch-McArdle when you know your body fat percentage (measured by DXA, BIA scale, or skinfold callipers). Katch-McArdle calculates BMR from Lean Body Mass (LBM) rather than total body weight: BMR = 370 + (21.6 × LBM in kg). This makes it more accurate for athletes with high muscle mass (who would see over-estimated BMR from Mifflin-St Jeor) and for individuals with very high body fat percentages (who would see under-estimated BMR). Accuracy depends heavily on the body fat measurement method used.

Question 6

What is the WHO/FAO/UNU energy requirement method?

Accepted Answer

The WHO/FAO/UNU (2004) method uses Schofield (1985) equations to estimate BMR from weight, age, and sex — without height. Total Energy Expenditure (TEE) = Schofield BMR × Physical Activity Level (PAL). WHO PAL values range from 1.40 (sedentary) to 2.00 (very active). This approach is the global standard for population-level energy planning and clinical nutrition assessment, particularly in settings where accurate height measurement is unavailable.

Question 7

Can I use inches and pounds instead of centimetres and kilograms?

Accepted Answer

Yes. The calorie needs calculator includes a Metric / Imperial unit toggle. When you switch to Imperial, all measurement fields convert automatically from centimetres to inches and kilograms to pounds. All internal calculations use metric values, so results are identical regardless of which unit system you choose.

Question 8

What are the minimum safe calorie levels?

Accepted Answer

Clinical guidelines generally recommend minimum calorie floors of 1500 kcal/day for men and 1200 kcal/day for women without medical supervision. Very Low Calorie Diets (VLCD) below 800 kcal/day require physician oversight and are associated with lean mass loss, nutrient deficiencies, gallstone formation, and metabolic adaptation. The Weight Goal Planner automatically applies these floors if your calculated target falls below them.

Question 9

How often should I recalculate my calorie needs?

Accepted Answer

Recalculate every 4–6 weeks, or whenever your weight changes by 3–5 kg. Your BMR decreases as you lose weight (metabolic adaptation), meaning your TDEE falls over time — what was a 500 kcal deficit initially may become a 300 kcal deficit after significant weight loss. Track weekly average body weight (to smooth out daily fluctuations from water retention) and adjust calorie targets accordingly.

Type	Description
Maintenance Calories	Calories to maintain weight
Weight Loss	Calorie deficit for weight loss
Weight Gain	Calorie surplus for weight gain

Type	Description
Maintenance Calories	Calories to maintain weight
Weight Loss	Calorie deficit for weight loss
Weight Gain	Calorie surplus for weight gain

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