🥑 What Is the Ketogenic Diet?
The ketogenic (keto) diet is a very low-carbohydrate, high-fat eating pattern that shifts the body's primary fuel source from glucose to ketones — molecules produced from fat in the liver. By restricting net carbohydrates to typically 20–50g per day, insulin levels drop, glycogen stores deplete, and the liver begins converting fatty acids into ketone bodies (beta-hydroxybutyrate, acetoacetate, acetone).
This metabolic state — known as nutritional ketosis — has been studied for fat loss, epilepsy management, blood sugar control, and cognitive function. The key is maintaining carbohydrates below your personal ketosis threshold, which varies between individuals but is typically 20–50g net carbs per day.
🧮 How the Keto Macro Calculator Works
Unlike a standard macro calculator where carbs are set as a percentage of calories, the keto calculator works differently — carbs are fixed at a maximum gram amount (the ketosis threshold), and the remaining calories are split between fat and protein.
Your Total Daily Energy Expenditure is estimated using the Mifflin-St Jeor BMR equation multiplied by your activity factor. This is your calorie maintenance level.
Fat loss subtracts 500 kcal (creating a ~0.5 kg/week deficit), maintenance uses your exact TDEE, and lean gain adds 200 kcal for a controlled surplus.
Based on your chosen keto protocol, net carbs are capped at 20g (Standard), 30g (Targeted), or 50g (Cyclical). This is the non-negotiable constraint that maintains ketosis.
Protein is set at approximately 20% of total calories — enough to preserve lean muscle without being so high that gluconeogenesis (protein-to-glucose conversion) kicks you out of ketosis.
All remaining calories come from fat. On keto, fat is typically 65–80% of total calories — the primary energy substrate replacing glucose.
📋 The 3 Keto Protocols Explained
Best for: Beginners, fat-loss focus, people with type 2 diabetes or insulin resistance
Best for: Gym-goers, athletes, anyone doing HIIT or resistance training
Best for: Bodybuilders, strength athletes, advanced keto users
🍽️ What to Eat on a Keto Diet
🔢 Net Carbs vs Total Carbs: What's the Difference?
On a ketogenic diet, you track net carbs — not total carbs. Net carbs are the carbohydrates that actually affect blood sugar and insulin, which are the carbs that can disrupt ketosis.
Dietary fibre is not digested or absorbed as glucose — it passes through the gut intact. Most sugar alcohols (erythritol, xylitol) have minimal glycaemic impact. However, maltitol has a significant effect and should not be subtracted.
⚡ The Keto Flu & Electrolytes — What You Need to Know
The "keto flu" — fatigue, headaches, brain fog, and muscle cramps in the first 1–2 weeks — is almost entirely caused by electrolyte and fluid loss, not fat adaptation itself. As insulin drops, the kidneys excrete more sodium, and magnesium and potassium follow.
⚖️ Keto vs Other Low-Carb Approaches
Is keto safe long-term?
For most healthy adults, long-term keto is considered safe and has been studied extensively in epilepsy patients for decades. Short-term studies show benefits for weight loss, blood sugar, and triglycerides. Longer-term research (2+ years) is limited. Those with kidney disease, gallbladder issues, or who are pregnant should consult a doctor before starting keto.
Why is protein moderated on keto?
Very high protein intake on keto can trigger gluconeogenesis — the liver's ability to convert amino acids into glucose. While this rarely kicks people out of ketosis in practice, moderate protein (15–25% of calories) is the standard recommendation to prevent unnecessary glucose production while still protecting muscle mass.
Keto and exercise: what to expect
Fat-adapted athletes perform equally or better in endurance and strength training once past the adaptation phase (2–6 weeks). However, activities requiring rapid glucose — sprinting, CrossFit, explosive lifts — may suffer on SKD. TKD or CKD protocols with strategic carb timing around workouts address this limitation effectively.
Tracking ketosis — how do you know it's working?
Urine ketone strips are inexpensive but lose accuracy as you adapt (kidneys stop excreting as many ketones). Blood ketone meters (0.5–3.0 mmol/L = nutritional ketosis) are the gold standard. Breath meters offer a middle ground. Early signs without testing: reduced appetite, metallic taste, increased mental clarity, slightly fruity breath.
🍽️ Sample Keto Day of Eating (Standard — 2,000 kcal)
Frequently Asked Questions
How many carbs can I eat on keto and stay in ketosis?
Most people achieve and maintain nutritional ketosis at 20–50g net carbs per day. The standard ketogenic diet caps net carbs at 20g for reliable ketosis. Some metabolically flexible individuals (especially active people) can remain in ketosis at 50g or slightly above. Blood ketone testing (0.5–3.0 mmol/L) is the most reliable way to confirm your personal threshold.
What is the difference between total carbs and net carbs?
Net carbs = Total carbs − Dietary fibre − Most sugar alcohols. Dietary fibre is not digested or absorbed into the bloodstream as glucose — it feeds gut bacteria and supports digestion without raising insulin. Sugar alcohols vary: erythritol and xylitol have minimal impact; maltitol behaves more like sugar and should be counted.
How long does it take to get into ketosis?
Most people enter nutritional ketosis within 2–4 days of restricting carbohydrates below 20–50g net carbs. Full fat-adaptation — where muscles preferentially use fat efficiently — takes 4–8 weeks. The initial 2–3 weeks often feel hardest due to electrolyte losses and the body's adjustment period. Fasting or prolonged exercise can accelerate the process.
What is the keto flu and how do I avoid it?
The keto flu (fatigue, headaches, brain fog, muscle cramps) is caused by electrolyte and fluid loss that occurs as insulin drops and the kidneys increase sodium excretion. To prevent it: aggressively supplement sodium (2–4g/day from salt and broth), potassium (from avocado, leafy greens), and magnesium (supplement with glycinate form). Most people who prepare electrolytes in advance experience minimal symptoms.
Does keto work for building muscle?
Muscle building on keto is possible but requires attention to protein intake and potentially using the Targeted or Cyclical protocol. Research shows that keto athletes preserve lean mass effectively. However, carbohydrates drive insulin — an anabolic hormone — and replenish muscle glycogen for performance. For serious strength athletes or bodybuilders, TKD or CKD with strategic carb timing around training typically produces better results than SKD.
Can I drink alcohol on keto?
Pure spirits (vodka, whiskey, tequila, gin) contain zero carbs and are keto-compatible in moderation — though alcohol is metabolised before fat and temporarily pauses ketosis. Dry wines (red or white) have 2–4g net carbs per glass. Beer is almost entirely off-limits (12–20g carbs per can). Cocktails with sugar mixers, juice, or syrups are not compatible with standard keto.
Is intermittent fasting compatible with keto?
Intermittent fasting (IF) and keto are highly complementary. Fasting naturally extends the ketotic state and accelerates fat adaptation. The most common combination is 16:8 IF (eating within an 8-hour window). Many keto practitioners find that hunger suppression from ketones makes IF easier to maintain. Starting keto and IF simultaneously can be challenging — it is usually recommended to stabilise on keto first.