Your Daily Protein, Carbs and Fat — Calculated for Your Goal
Counting calories alone misses the point. Two people eating 2,000 calories can get completely different results depending on how those calories are split between protein, carbs, and fat. This calculator uses the Mifflin-St Jeor equation — the most validated BMR formula for healthy adults — to work out your TDEE, then applies goal-matched macro splits with per-meal breakdowns.
Matched to Your Goal
Selected based on your goal and diet style.
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Why Macros Matter More Than Calories Alone
Calorie counting became popular in the 1960s off the back of Ancel Keys’ research and the idea that weight was purely a function of energy in versus energy out. That framing is not wrong — but it is incomplete. Two people eating 2,000 calories per day can have completely different body composition outcomes depending on how those calories are distributed between protein, carbohydrates, and fat.
Protein has a thermic effect of 20-30% — meaning roughly a quarter of its calories are burned just through digestion. Carbohydrates burn 5-10% through digestion. Fat burns almost nothing (0-3%). A high-protein diet at the same calorie level as a low-protein diet will result in measurably higher total energy expenditure, better muscle retention during a deficit, and greater satiety. The calories are equal; the results are not.
Formula used: This calculator uses the Mifflin-St Jeor equation (1990), validated against indirect calorimetry and shown to predict BMR within 10% for most healthy adults — more accurate than the older Harris-Benedict equation (1919) for most populations. BMR is then multiplied by an activity factor (1.2–1.9) to give TDEE, and adjusted up or down based on your goal.
The Five Diet Styles — What Each Split Actually Does
Balanced (30% protein / 40% carbs / 30% fat)
The Institute of Medicine’s Acceptable Macronutrient Distribution Ranges sit at 10-35% protein, 45-65% carbs, and 20-35% fat. The balanced preset sits within those ranges and works well as a starting point for most people who are not pursuing a specific body composition goal. It is the split most consistent with general dietary guidelines and the easiest to maintain long-term.
High Protein (40% protein / 30% carbs / 30% fat)
The research on protein intake for muscle preservation during a calorie deficit is consistent: higher protein (0.7-1.0g per pound of bodyweight) produces better outcomes. A 2014 meta-analysis in the American Journal of Clinical Nutrition found that high-protein diets produced significantly greater fat loss and muscle retention compared to standard protein intakes during energy restriction. This split is appropriate for anyone in a calorie deficit who wants to minimise muscle loss, or for anyone focused on building muscle.
Low Carb (35% protein / 25% carbs / 40% fat)
Reducing carbohydrates lowers insulin response, which can benefit people with insulin resistance or those who find they feel better with fewer blood sugar fluctuations. At 25% carbs, this is not ketogenic — it still provides enough glucose for moderate exercise. This split works well for people who do not depend on high-carbohydrate intake for performance and prefer the satiety profile of higher fat intake.
Keto (30% protein / 5% carbs / 65% fat)
At under 50g of carbohydrates per day (usually under 30g to reliably enter ketosis), the liver produces ketone bodies from fat as the primary fuel source. Ketogenic diets show good short-term results for weight loss and metabolic markers in some populations. The limitation is adherence — fat provides 9 kcal per gram versus 4 kcal for protein and carbs, so staying within a calorie budget while eating 65% fat requires careful planning.
Endurance (25% protein / 55% carbs / 20% fat)
Athletes training for endurance events — running, cycling, swimming — depend on glycogen stores for performance. Glycogen is synthesised from carbohydrates. At higher training volumes, carbohydrate intake of 5-7g per kilogram of bodyweight is recommended by the American College of Sports Medicine. This split prioritises carbohydrates to fuel training and recovery, with protein still sufficient for muscle repair.
| Diet Style | Protein | Carbs | Fat | Best For |
|---|---|---|---|---|
| Balanced | 30% | 40% | 30% | General health, starting point |
| High Protein | 40% | 30% | 30% | Fat loss, muscle building |
| Low Carb | 35% | 25% | 40% | Insulin sensitivity, satiety |
| Keto | 30% | 5% | 65% | Metabolic conditions, some weight loss |
| Endurance | 25% | 55% | 20% | Distance athletes, high-volume training |
Protein: The One Macro You Almost Certainly Under-Eat
The RDA for protein (0.8g per kilogram of bodyweight) is the minimum needed to prevent deficiency — not the amount needed to optimise body composition. For active adults, research consistently points to 1.6-2.2g per kilogram as the range that maximises muscle protein synthesis. A 70 kg active person needs 112-154g of protein per day to support muscle maintenance and growth — two to three times the RDA minimum.
Protein is also the most satiating macronutrient. A 2005 study in the American Journal of Clinical Nutrition found that increasing protein from 15% to 30% of calories led participants to spontaneously eat 441 fewer calories per day — with no other dietary instruction. The satiety effect of protein is real and large enough to matter in practice.
These Numbers Are Starting Points, Not Prescriptions
The Mifflin-St Jeor equation predicts BMR within 10% for most adults — meaning your actual metabolic rate could be 10% higher or lower than the calculated figure. Activity multipliers carry additional uncertainty. The right approach is to treat your calculated targets as a starting point, track your actual intake for 2-3 weeks, and adjust based on real-world results. If your weight is not moving as expected, adjust calories by 100-150 kcal per day and reassess after two more weeks. The calculation tells you where to start; your body tells you where to go.