Health & Fitness

Find out how many calories you need each day based on your age, sex, size, and activity level – with the formula, worked examples, and safe targets for every goal.

Learn how much protein you need per day by weight and goal – from the 0.8 g/kg minimum to muscle-building targets – with worked examples and food guides.

Estimate your body fat percentage with just a tape measure: Navy method formulas for men and women, a worked example, and healthy ranges to compare against.

How much water should you drink a day? The real science behind daily water intake, a simple body-weight formula, and why the 8×8 rule falls short.

Healthy BMI runs 18.5 to 24.9, but the same table is applied to every age and population. Here is where it needs qualifying.

The Devine formula was built in 1974 to calculate drug doses, not goal weights. A look at what the four ideal weight formulas actually tell you.

The standard ovulation formula, worked through for different cycle lengths, plus the assumption behind it that most guides never mention.

The calculation takes two seconds; the measurements are where people go wrong. Exactly where to place the tape, and what your ratio means.

Naegele’s rule, the cycle-length adjustment it assumes away, and why a first-trimester scan beats the arithmetic.