Guides
Short, practical explainers that walk through the concepts behind our calculators — and link you straight to the tool that does the math.
How Many Calories Should I Eat to Lose Weight?
A plain-English guide to calorie deficits: how to find your maintenance calories, how big a deficit to run, and how to turn the number into a daily plan.
Updated July 15, 2026
How Much Protein Do You Really Need Per Day?
What the research says about daily protein: the RDA versus targets for active people, how to split protein across meals, and how much is too much.
Updated July 15, 2026
What BMI Does and Doesn't Tell You
BMI is quick and useful as a screening tool, but it has real limits. Here is what the number means, where it misleads, and what to look at alongside it.
Updated July 15, 2026
Why TDEE Calculators Are Estimates (and How to Dial Yours In)
TDEE formulas have a margin of error of about 10%. Here's why, and how to use two to three weeks of real data to find your true maintenance calories.
Updated July 15, 2026
How to Calculate Your BMR (Basal Metabolic Rate)
A plain-English guide to BMR: what it measures, the two main formulas (Mifflin-St Jeor and Harris-Benedict), a worked example, and how to turn your BMR into a usable calorie target.
Updated July 16, 2026
How Much Water Should You Drink a Day?
Where the '8 glasses' rule actually comes from (and why it has no scientific basis), what EFSA and the National Academies actually recommend, and how to tell if you are drinking enough.
Updated July 16, 2026
How Long Does It Take to Lose Weight?
The math behind weight loss timelines: how the 7,700 kcal per kilogram model works, what a realistic weekly rate looks like, why the scale moves faster at first, and why loss slows over time.
Updated July 16, 2026