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body better.
Evidence-based guides on fitness, nutrition, and understanding health metrics.
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Your Cycle's Range Tells You More Than Its Average
Shift Work and Sleep: Why Night Shifts Fight Your Circadian Rhythm and What Helps
Night shift workers fight their own circadian rhythm — bright daylight signals "daytime" to the brain exactly when they need to sleep. Here's why standard sleep hygiene isn't enough for shift workers, the strategic light exposure techniques (including sunglasses on the commute home), rotating shift challenges, and napping strategies for night shifts.
Planning Leave Around Your Due Date: Why "Count Back From the Due Date" Is Just the Starting Point
"My due date is March 15th" doesn't directly answer "when should I start my leave" — leave planning means working backward from an estimated date, applying jurisdiction-specific policies, and building in a buffer for the very real possibility of early arrival. Here's why most leave frameworks let leave begin automatically upon birth regardless of the planned date, why work-handover targets should sit several weeks before the planned leave-start date, and why partner/co-parent leave planning is inherently date-range-based rather than fixed.
Period Tracking and Contraception: Why Predictions Mean Different Things Depending on Your Method
A period tracker calculates predictions based on natural cycle mechanics — but hormonal contraception works precisely by overriding that cycle, meaning "fertile window" predictions can mean something completely different (or nothing at all) depending on the method. Here's how combined pills, progestin-only methods, hormonal IUDs, and copper IUDs each affect what a tracker can meaningfully predict.
Body Fat Percentage Tracking: Why Your Daily Reading Swings 3% and What to Actually Pay Attention To
A body-fat reading that swings 2-3 percentage points overnight isn't your body composition changing that fast — actual fat changes occur over weeks, while day-to-day swings are almost entirely hydration, meal timing, and measurement-method noise. Here's why a consistent measurement protocol matters more than any single reading's accuracy, why trend lines over weeks reveal the real signal, and why switching measurement methods means starting a new trend, not continuing the old one.
Why "Exact Age in Years, Months, and Days" Has More Than One Right Answer — and What Happens If You're Born on Feb 29
"33 years, 9 months, 21 days" sounds precise — but because months have different lengths, the algorithm used to calculate the "months and days" portion involves a genuine implementation choice that can produce different results for the same two dates. Here's how the year/month/day "borrowing" algorithm works, why February 29th birthdays create a recurring ambiguity with real legal implications, and why "months" as a unit is inherently approximate.
"Ideal Weight" Gives You One Number — Health Guidance Gives You a Range, and the Difference Matters
"Ideal weight" formulas all output a single number — but health guidance (BMI ranges) is expressed as ranges, not single targets, and the gap between "a single target" and "a healthy range" matters for how people relate to these numbers. Here's why single-number framing can create "missed the target" feelings even within a healthy range, why it can encourage precision-seeking behaviors that body-fat-tracking articles already cautioned against, and why "healthy weight range" is generally the more useful framing.
DEXA, BIA, Calipers, and Hydrostatic Weighing: How Body Fat Measurement Methods Compare
DEXA, hydrostatic weighing, BIA scales, and skinfold calipers can give different body fat percentages for the same person on the same day. Here's what each method actually measures, why BIA scales are so sensitive to hydration, and how to choose between accuracy and practicality for tracking your own body composition.
Muscle, Metabolism, and Aging: Why Sarcopenia — Not "Slowing Down" — Explains Metabolic Change
A landmark study tracking 6,400 people found metabolism is remarkably stable from age 20 to 60 — what actually changes is muscle mass. Here's the Pontzer 2021 findings, how sarcopenia drives the "skinny fat" phenomenon, why protein needs increase with age, and why resistance training is the primary evidence-based intervention.
Ketogenic Diets and Nutritional Ketosis: What the Research Shows About Weight Loss, Performance, and Who Should Be Cautious
Ketogenic diets shift the body's fuel source from glucose to fat and ketones — a measurable metabolic state with the strongest evidence base in drug-resistant epilepsy. Here's how nutritional ketosis differs from dangerous diabetic ketoacidosis, what weight loss research actually shows over longer timeframes, and the mixed evidence on athletic performance.
Harris-Benedict vs Mifflin-St Jeor vs Katch-McArdle: Why BMR Formulas Disagree by 100-200 Calories
BMR calculators don't all use the same formula — Harris-Benedict (1919, revised 1984), Mifflin-St Jeor (1990), and Katch-McArdle (lean-mass-based) can disagree by 100-200 calories for the same person, which represents 20-30% of a typical weight-loss deficit. Here's how each formula was developed, why they diverge more for people at the extremes of body composition, and why any formula's output should be treated as a starting point rather than a precise target.
BMI and Pregnancy: Why Pre-Pregnancy BMI Matters and "Current BMI" During Pregnancy Doesn't Mean What You'd Think
A pregnant person's BMI increases throughout pregnancy simply because of the pregnancy itself — applying standard BMI categories to this changing number would be meaningless. Here's why clinical weight-gain guidance uses pre-pregnancy BMI as a fixed reference point instead, why "total weight gain from that reference point" is the relevant question rather than "current BMI category," and how postpartum BMI takes time to become meaningful again.
BMI and Ethnicity: Why the WHO Recommends Lower Thresholds for Asian Populations
A BMI of 24 is "normal" by standard categories but already represents "increased risk" under WHO's Asian-specific BMI cut-offs (23 for overweight, 27.5 for obese). Here's why these adjustments exist, the body composition research behind them, UK NICE guidance for multiple ethnic groups, and why waist circumference complements BMI across populations.
