Guides
Nutrition and Diet Calculator Guides
Plain-English guides that explain how each SmartDietChoices calculator works: the formula behind it, a worked example, how to read the result, and where its limits lie. Every guide links to the matching calculator so you can run your own numbers.
The calculators give you a fast answer. These guides give you the reasoning: what the number means, which inputs move it, and how to act on it safely. Each one is written to be read on its own, with formulas, examples, and interpretation tables, and every result they describe is an estimate rather than medical advice. Pick a topic below, or start from any calculator and follow the "Learn how this works" link.
Lose Weight
4 guidesHow to calculate a calorie deficit
Maintenance minus a safe deficit, and how weekly loss adds up. Read guideHow calorie cycling works
Vary daily calories while keeping one weekly deficit. Read guideHow to calculate weight loss percentage
The formula and what the 5 and 10 percent milestones mean. Read guideHow to set macros for cutting
High protein to keep muscle while you lose fat. Read guideBuild Muscle
4 guidesHow to calculate macros
Protein first, a fat floor, then carbs fill the rest. Read guideHow much protein do you need
Daily protein by goal and body weight. Read guideHow body recomposition works
Lose fat and build muscle at the same time. Read guideHow many calories to gain weight
Surplus sizing and a safe rate of gain. Read guideTrack Food
5 guidesHow to calculate keto macros
Keto ratios and how to count net carbs. Read guideChoosing a fasting schedule
Compare 16:8, 18:6, 20:4, and OMAD windows. Read guideHow to calculate calories in a recipe
Total ingredients, then divide by servings. Read guideHow much water should you drink
A body-weight baseline plus exercise and climate. Read guideHow many calories does walking burn
The MET method and step-to-calorie conversion. Read guideBody Metrics
4 guidesHow to calculate TDEE
BMR, activity multipliers, and maintenance calories. Read guideTDEE for women
Female inputs, the equation constant, and cycle effects. Read guideWhat is FFMI
Lean mass for your height, and how to read the bands. Read guideHow to calculate waist-to-height ratio
The formula, measuring your waist, and the bands. Read guidePrefer to jump straight to the tools? Browse every calculator by goal on the homepage, read the methodology page for the formulas and sources behind them, or see how we build and check each one. Calculator results and guide examples are estimates, not medical advice; see our health disclaimer.