Guide
These are population formulas applied to one person: you
Every health guide here explains an equation (Mifflin-St Jeor for calorie needs, the standard BMI ratio, activity multipliers for TDEE), and every one of those equations was built from population averages, not from you specifically. Mifflin-St Jeor alone carries roughly a 10% error band for an individual even with height, weight, age, and sex entered correctly. Read the guide for the method, then treat the number it produces as a starting point to test.
The workflow that actually works: take the estimate, act on it for two or three weeks, and correct from what happened. If a calorie target predicts maintenance and your weight steadily drops at that intake, your real maintenance is higher than the formula said, and that measured result should now override the original estimate.
Articles
Where to start in health
If you only read one article here, start with Macro Counting Guide: Convert Calories to Grams. These cover the most common questions in this category and link to the calculator that matches.
23 articles are published in this category so far. Each one follows the same structure: the formula or method, a worked example, a comparison table where relevant, and a direct link to the live calculator.
Context
The input that breaks health estimates most often
Activity level is where most estimates go wrong. Guides describe activity tiers ("lightly active," "moderately active") in general terms, and most readers pick the tier for the week they intend to have rather than the week they actually have, which can overstate daily calorie needs by several hundred calories and quietly erase an intended deficit. Pick the honest tier, including the days you skip a workout.
For cycle, pregnancy, and pace articles, the guide’s worked example assumes a regular, known cycle length or trained fitness. If either assumption does not hold for you, read the resulting dates or paces as a window rather than a fixed number.
Scenarios
Comparisons that are more useful than a single number
Reading BMR against TDEE side by side shows how much of your daily energy use comes from activity rather than from simply being alive, commonly 400 to 900 calories, which reframes how much a single workout actually offsets. Set a calorie deficit against TDEE, not BMR: 300 to 500 calories below maintenance is the range guides consistently describe as sustainable.
For a pace or training guide, check the target pace it recommends against paces you have actually held in recent sessions. If the guide’s target is well outside your recent training, the goal needs revising before the plan does.
Comparison
Why two health guides can give different numbers for the same input
Mifflin-St Jeor and Harris-Benedict can differ by 100 calories or more for the same person, and BMI, body-fat percentage, and ideal-weight guides can each classify one individual differently, because each is measuring something different, not because one article is wrong. Treat a single figure from a single guide as one reading among several rather than a verdict.
What matters more than the exact number is the direction it moves over time. If a body-composition estimate trends down while your scale weight holds steady, that trend is informative even if neither individual reading is precisely accurate.
Limits
Where a guide stops and a clinician starts
None of these articles can evaluate symptoms, medication interactions, thyroid or metabolic conditions, pregnancy complications, or disordered eating patterns, because they do not know your medical history. If following a guide’s recommendation would mean a very low intake, ignoring hunger or pain, or overriding a symptom, that is a reason to talk to a clinician rather than a target to push through.
These guides are educational estimates for general wellness planning, not a diagnosis or a treatment plan. Use them as material for a conversation with a qualified professional, especially if you are pregnant, managing a condition, or on medication that affects appetite or metabolism.