The number, and how wrong it might be.
Every calorie calculator gives you one number. It has an error of ten percent.
Maintenance, a deficit, a protein target — the arithmetic takes ten seconds and every site on the internet prints it. What almost none of them print is that the equation underneath is a regression fitted to a few hundred people, that its standard error is about ten percent, and that the number falls as you do. Those three facts decide whether the plan works.
This site does the same arithmetic as every other calorie calculator and then shows the part they leave out: the band each figure sits in, and what happens to it over the months a plan actually runs.
What is here
A calculator that returns ranges rather than a single figure, and that models the fall in maintenance as weight falls instead of pretending the line is straight. Written pages on what maintenance is and is not, how much of a loss is fat rather than lean tissue and what moves that ratio, and how to read a nutrition label including the rounding rules that let a label print zero for something that is not zero.
What is not here
No meal plans, no supplements, no products, and no before-and-after photographs. No claim that any rate of loss is achievable or safe for a particular person, because that is a clinical judgement and this is a page of arithmetic. No diet is named as better than another: the evidence on adherence is that the one a person will actually follow beats the one that is theoretically optimal, and a site cannot know which that is.
Calories in, calories out, and what neither one measures
What maintenance actually is, how much the estimate can be trusted, what happens to it as weight falls, and why the same deficit produces different results in month one and month four.
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BMR: What the Equations Actually Estimate
Basal metabolic rate is the energy cost of staying alive. Mifflin-St Jeor, Harris-Benedict and Katch-McArdle give different numbers; here is the spread.
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How Wrong Is Your Calorie Count? Error Sources and Ranges
Calorie counting accuracy depends on label error, database variance, portion estimation, and cooking. This page stacks those errors and shows the real range.
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How Big a Calorie Deficit? A Reference Guide
How large a calorie deficit should be: derive maintenance from Mifflin-St Jeor, apply 15–20%, and see worked examples at 10%, 20%, and 30% below maintenance.
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What Exercise Actually Burns: A Reference on Energy Cost
Exercise burns less than most readouts claim. See how calories burned are derived, why watches run high, and how compensation erodes the deficit.
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The 7,700 Calorie Rule and Where It Breaks
The 7,700 kcal per kg rule describes adipose tissue, not body weight. See the equation, its two failure modes, and a worked example with real numbers.
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BMI and Body Fat: What Each Measure Is For
BMI is a population screening tool, not a diagnosis. Body fat estimates carry 3-5 point errors. Learn what each figure depends on and how to read it.
Protein, and the number that decides what you lose
Weight loss is a mixture of fat and lean tissue, and protein intake is the largest lever on the ratio. How much, from what, and which of the commonly repeated figures survive contact with the evidence.
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Fibre Intake: The Macronutrient Beside Protein
Fibre intake targets are 25–30 g daily; typical intake is half that. See how fibre and protein work together, with worked calculations and food sources.
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How Much Protein Per Day: RDA vs. Deficit Targets
The RDA for protein is 0.8 g/kg, a minimum to prevent deficiency. For muscle retention in a deficit, evidence clusters at 1.6–2.2 g/kg. Worked examples inside.
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High-Protein Foods: Ranking by Protein per 100 kcal
Ranking high-protein foods by protein per 100 kcal, not per 100 g. Includes a table, worked example, and the RDA vs. deficit target distinction.
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Protein and Muscle Loss in a Calorie Deficit
Protein needs to lose fat not muscle: RDA vs. deficit targets, grams per kilogram, and the limits of body recomposition. Not medical advice.
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Plant Protein: How Much and From Where
Plant protein needs are 10–20% higher than animal protein due to lower digestibility. Learn grams per kilogram, DIAAS scores, and food sources.
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Protein per Calorie: The Ratio That Matters
Protein per calorie reorders food lists. Chicken breast beats almonds by 5x. Work the ratio, see the RDA vs. deficit target, and avoid the common swap.
Eating for mass, and the rate that decides the surplus
How large a surplus should be, how fast muscle can actually be built, and why a surplus bigger than that rate can support adds fat and nothing else.
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Calories to Gain Weight: Surplus Arithmetic
Calories to gain weight: derive a surplus from Mifflin-St Jeor maintenance, see what 200-500 kcal adds per month, and why larger surpluses add fat.
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How to Gain Weight: The Arithmetic of a Surplus
Gaining weight is an intake problem, not a metabolic one. Mifflin-St Jeor maintenance, a 10% error band, and how much surplus muscle can actually use.
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Lean Bulk vs Dirty Bulk: Surplus Arithmetic
Lean bulk vs dirty bulk: how surplus size changes fat gain, the rate muscle can be built, and the deficit that follows. Worked numbers and sources.
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Protein in a Surplus: How Much to Build Muscle
In a surplus, about 1.6 g/kg protein covers muscle gain; above 2.2 g/kg adds nothing measurable. Derivation, uncertainty, and the surplus arithmetic.
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How Fast Muscle Can Be Built: Rates and Conditions
Published rates for lean mass gain are 0.2–0.5 kg per month for trained men and about half that for women. The surplus that supports it is small.
Reading a label, and what it does not tell you
Where nutrition numbers come from, the rounding rules that make a zero not a zero, why the same food differs by twenty percent between databases, and how to compare two products honestly.
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How Low Can Carbohydrate or Fat Go: A Reference
Low carb vs low fat: controlled trials show small differences when calories and protein match. Here are the arithmetic floors for fat and carbohydrate.
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Are Calorie Labels Accurate? Food Data and Tolerance
Calorie labels use Atwater factors, not bomb calorimetry. Learn the permitted tolerance, rounding rules, and how to recover the real figure from a label.
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Cooked vs Raw Weight: Why the Number Changes
Cooked vs raw weight changes the calorie count you look up. Learn the conversions for rice, chicken, and pasta, and one rule for everything else.
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Why Two Food Databases Give Different Numbers
Food database accuracy varies by source. USDA data, manufacturer labels, and user entries give different numbers for the same food. Here is why and how to read them.
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Macronutrient Splits: Protein, Fat, Carbohydrate
Macronutrient splits explained: set protein from body weight, fat to a floor, carbohydrate the remainder. Includes worked examples and label arithmetic.
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How Badly People Estimate a Portion
Estimated portions run 20–30% low, and worse for calorie-dense foods. Learn where nutrition numbers come from, how to read them, and why a scale beats guessing.