SmartDietChoices

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 guides
How to calculate a calorie deficitMaintenance minus a safe deficit, and how weekly loss adds up.→ How calorie cycling worksVary daily calories while keeping one weekly deficit.→ How to calculate weight loss percentageThe formula and what the 5 and 10 percent milestones mean.→ How to set macros for cuttingHigh protein to keep muscle while you lose fat.→

Build Muscle

4 guides
How to calculate macrosProtein first, a fat floor, then carbs fill the rest.→ How much protein do you needDaily protein by goal and body weight.→ How body recomposition worksLose fat and build muscle at the same time.→ How many calories to gain weightSurplus sizing and a safe rate of gain.→

Track Food

5 guides
How to calculate keto macrosKeto ratios and how to count net carbs.→ Choosing a fasting scheduleCompare 16:8, 18:6, 20:4, and OMAD windows.→ How to calculate calories in a recipeTotal ingredients, then divide by servings.→ How much water should you drinkA body-weight baseline plus exercise and climate.→ How many calories does walking burnThe MET method and step-to-calorie conversion.→

Body Metrics

4 guides
How to calculate TDEEBMR, activity multipliers, and maintenance calories.→ TDEE for womenFemale inputs, the equation constant, and cycle effects.→ What is FFMILean mass for your height, and how to read the bands.→ How to calculate waist-to-height ratioThe formula, measuring your waist, and the bands.→

Prefer 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.