Frequently Asked Questions
Expert, evidence-based answers covering Body Mass Index screening, caloric energy metabolism, fertility windows, and gestational milestones.
Body Mass Index (BMI) FAQs
Body Mass Index (BMI) is an epidemiological screening index of weight-for-height. It is calculated by dividing body weight in kilograms by the square of height in meters: BMI = kg / m². For imperial units: (lbs × 703) / inches².
BMI cannot differentiate between dense skeletal muscle and adipose fat tissue. Muscular athletes often register as "overweight". Furthermore, it does not assess fat distribution (such as visceral belly fat). Pair your BMI with waist-to-height ratio and body fat % for complete assessment.
According to the World Health Organization (WHO), a standard healthy adult BMI is between 18.5 and 24.9 kg/m². Below 18.5 is underweight, 25.0 to 29.9 is overweight, and 30.0 or higher indicates clinical obesity.
Our calculator applies the validated Deurenberg epidemiological formula to estimate body fat % from BMI, age, and sex. Essential body fat ranges between 10–22% for adult men and 20–32% for adult women.
Calorie, BMR & Macro FAQs
Basal Metabolic Rate (BMR) is the baseline caloric energy required to sustain vital autonomic organs (brain, liver, heart, lungs) in a resting state. Total Daily Energy Expenditure (TDEE) accounts for BMR plus physical movement, work activity, and the thermic effect of food (TEF).
Clinical guidelines recommend a moderate deficit of 300 to 500 kcal/day below TDEE. This reliably yields approximately 0.6 to 1.0 lb of pure fat loss per week while sparing lean muscle mass and preventing severe metabolic adaptation.
During a caloric deficit, target 1.6 to 2.2 grams of protein per kilogram of bodyweight (0.73–1.0 g/lb). High protein stimulates muscle protein synthesis (MPS) and maximizes satiety via peptide YY and GLP-1 signaling.
Systematic reviews by the Academy of Nutrition and Dietetics consistently validate the Mifflin-St Jeor equation as predicting resting metabolic rate within ±10% of indirect calorimetry in both non-obese and obese individuals.
Ovulation & Fertility FAQs
In a standard 28-day cycle, ovulation occurs approximately on Day 14. Because the post-ovulatory luteal phase is physiologically stable at ~14 days, your ovulation day is calculated by subtracting 14 days from your average total cycle length.
The biological fertile window spans 6 days: the 5 days preceding ovulation plus ovulation day itself. Sperm can survive in fertile cervical mucus for up to 5 days, while an ovulated egg remains viable for 12 to 24 hours.
Key biomarkers include stretchy, clear egg-white cervical mucus (EWCM), a surge in Luteinizing Hormone (detected on LH urine test strips), and a sustained 0.3°C–0.6°C rise in Basal Body Temperature (BBT) caused by progesterone.
Implantation occurs 6 to 12 days past ovulation (DPO). High-sensitivity early-detection hCG tests can detect pregnancy as early as 10–12 DPO, though testing on the first day of a missed period offers over 99% clinical accuracy.
Pregnancy Due Date & Gestation FAQs
Our calculator applies clinical Naegele's rule: adding 280 days (40 gestational weeks) to the first day of your Last Menstrual Period (LMP), mathematically adjusted for your average menstrual cycle length.
Statistically, only about 4% to 5% of babies are born on their exact EDD. However, approximately 85% to 90% arrive within a normal full-term window of 37 to 42 completed gestational weeks.
1st Trimester: Weeks 1 through 13 (organogenesis and neural tube development). 2nd Trimester: Weeks 14 through 27 (rapid fetal growth and anatomy ultrasound scan). 3rd Trimester: Weeks 28 through 40+ (lung maturation, fat storage, and delivery preparation).
The comprehensive mid-pregnancy anatomy scan is typically scheduled between Weeks 18 and 22. This detailed ultrasound assesses fetal cardiac chambers, brain ventricles, kidneys, limbs, spinal integrity, and placental location.