Nutrition
How much of each nutrient you need, such as protein, fiber, and sodium, and how to track what you eat.
Sleep
Why a drink helps you fall asleep and then disrupts the second half of the night, what it does to REM sleep and heart rate, how much it takes, and how to see the effect in your own data.
November 4, 2026 · 2 min read
Sleep
What a trial of caffeine 0, 3, and 6 hours before bed found, the meta-analysis behind the 8.8-hour rule for coffee, why sensitivity varies, and how to test your own cut-off.
November 4, 2026 · 3 min read
The WHO's limit of 10% of energy from free sugars and its 5% ideal, the AHA's 25 g and 36 g a day, how added and free sugars differ from total sugars, and how to find yours.
November 4, 2026 · 2 min read
The 400 mg a day for most adults that the FDA and EFSA cite, the 200 mg limits for a single dose and in pregnancy, how much caffeine common drinks hold, and why people differ.
November 4, 2026 · 2 min read
The WHO's limits of 10% of energy from saturated fat and 1% from trans fat, what that is in grams, what trials found about cutting saturated fat, why replacing it matters, and where the evidence is disputed.
November 4, 2026 · 4 min read
The National Academies' 2,300 mg a day for sodium and the WHO's 2,000 mg, the Adequate Intakes for potassium, how salt and sodium differ, and where most sodium in a diet comes from.
November 4, 2026 · 2 min read
What the US National Academies and the European Food Safety Authority say about total water intake, why "eight glasses a day" has no evidence behind it, how much of your water comes from food, and when you need more.
November 4, 2026 · 4 min read
Labs
What serum vitamin B12 and folate measure, why there's no sharp cut-off for deficiency, how homocysteine and methylmalonic acid help, who is at risk, and why lowering homocysteine hasn't prevented heart attacks.
November 4, 2026 · 3 min read
How "net carbs" subtract fiber and sometimes sugar alcohols from total carbohydrate, why no US or EU labelling rule defines them, why a European label's carbohydrate already leaves fiber out, and what that means for comparing numbers.
November 4, 2026 · 3 min read
Vitals
What a beta-hydroxybutyrate meter measures, the levels seen with fasting and low-carbohydrate diets, the 3.0 mmol/L threshold for diabetic ketoacidosis, and when a reading is an emergency.
November 4, 2026 · 3 min read
How the Dietary Reference Intakes set the Estimated Average Requirement, the Recommended Dietary Allowance, the Adequate Intake, and the Tolerable Upper Intake Level, why they're averages over time, and how to read your intake against them.
November 4, 2026 · 4 min read
Why a standard drink is 14 g of alcohol in the US, 13.45 g in Canada, 10 g in Australia, and 8 g in a UK unit, how to work out the alcohol in a drink, and what current guidance says about how much is low risk.
November 4, 2026 · 3 min read
Body
What BMR is, how the Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle equations differ, which one the evidence favours, and how far any estimate can be from you.
November 4, 2026 · 3 min read
Labs
How the omega-3 index measures EPA and DHA in your red blood cells, where its 4% and 8% marks come from, what trials of fish oil found, and how it relates to the omega-3s you eat.
November 4, 2026 · 4 min read
Labs
Why experts disagree on the level, the National Academies' 20 ng/mL (50 nmol/L), the Endocrine Society's 2024 advice against routine testing, what large trials found, and how much vitamin D the Dietary Reference Intakes recommend.
November 4, 2026 · 3 min read
Apple Health
A step-by-step guide to putting your iPhone's health data, your food diary, and your bank statements in one history, without counting anything twice.
October 27, 2026 · 4 min read
How much protein and fiber adults are advised to eat, why a single day says little, and how to follow your intake week by week from your food diary.
October 25, 2026 · 5 min read