Keto & Low-Carb Macro Calculator
Calculate personalised macronutrient targets for ketogenic or low-carb diets based on your body stats, activity level, and specific dietary approach.
Ketogenic Diet Guide
What Is Ketosis?
Ketosis is a metabolic state where the body burns fat for fuel instead of glucose. When carbohydrate intake drops below approximately 20-50g per day (depending on individual), glycogen stores are depleted within 1-3 days. The liver then converts fatty acids into ketone bodies (β-hydroxybutyrate, acetoacetate, acetone) which become the primary fuel for the brain and muscles. Blood ketone levels above 0.5 mmol/L indicate nutritional ketosis. Keto is distinct from diabetic ketoacidosis (DKA) — a da
Keto Macro Ratios
Strict ketogenic diet macros: 5-10% calories from carbs (20-50g/day), 20-25% from protein, 70-75% from fat. Fat is used to meet calorie requirements, not as a 'free food' to eat unlimited amounts of. Protein is kept moderate — excess protein can be converted to glucose (gluconeogenesis) and disrupt ketosis at high intakes. Net carbs = total carbs − fibre − half of sugar alcohols. Fibre is not digested or absorbed so does not affect blood glucose or ketosis. Total carbs shown on UK food labels in
The Keto Adaptation Period
Keto flu — the adaptation period (days 3-7 after starting): fatigue, brain fog, headaches, muscle cramps, and irritability. Caused by electrolyte loss (sodium, potassium, magnesium are excreted more rapidly when carbs are low) and the body's switch from glucose to ketone metabolism. Remedy: increase sodium intake (salt food liberally, bone broth), supplement potassium and magnesium, stay very well hydrated. Full keto-adaptation (fat-burning efficiency) takes 4-8 weeks — athletic performance typi
Evidence for Keto
Strong evidence: ketogenic diet is the gold standard treatment for drug-resistant childhood epilepsy (reduces seizures by 50%+ in approximately 50% of cases). Consistent evidence: keto produces equal or greater short-term weight loss than low-fat diets (mainly due to calorie reduction from food restriction). Moderate evidence: improves triglycerides, HDL cholesterol, and blood glucose control in type 2 diabetes. Weak/limited evidence: superior long-term weight loss vs other diets (adherence is t
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