Can keto help with epilepsy?

Yes. The ketogenic diet has a well-established medical use in treating drug-resistant epilepsy, particularly in children. The NHS and National Institute for Health and Care Excellence (NICE) both recognise the ketogenic diet as a treatment option for epilepsy when two or more anti-epileptic drugs have failed. The mechanism is not fully understood, but ketone bodies appear to stabilise neuronal excitability and reduce seizure frequency. Clinical trials show that about 50% of children on the medical ketogenic diet see a greater than 50% reduction in seizures, and up to 15% become seizure-free. The medical keto diet for epilepsy is much stricter (3:1 or 4:1 fat-to-protein+carb ratio) and is supervised by NHS dietitians. The dietary therapy should not be undertaken without specialist involvement.

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Keto Calculator UK

Q: How many carbs can I eat on keto?

On a standard ketogenic diet, you should aim for 20–50g of net carbs per day. Net carbs are calculated by subtracting fibre from total carbohydrates. Most people enter ketosis reliably at 20g net carbs or below. Higher activity levels or faster metabolism may allow up to 50g net carbs while staying in ketosis. Targeted keto allows an extra 20–30g of carbs around workouts. Cyclical keto involves 5 days of standard keto followed by 1–2 higher carb days (150–300g). For beginners, starting at 20g net carbs per day is recommended to ensure ketosis is established before experimenting with higher limits.

Q: What is ketosis and how long does it take to enter?

Ketosis is a metabolic state where your body burns fat for fuel instead of glucose. When carbohydrate intake is very low, the liver converts fatty acids into ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone), which fuel the brain and muscles. Glycogen stores are depleted within 24–48 hours of starting keto. Most people enter nutritional ketosis (blood ketones 0.5–3.0 mmol/L) within 2–7 days of strict carb restriction. Exercise speeds this up — a glycogen-depleting workout followed by low-carb eating can induce ketosis within 24 hours. You can test ketosis with urine strips, breath ketone metres, or blood ketone metres (most accurate).

Q: What is keto flu and how can I avoid it?

Keto flu refers to flu-like symptoms that some people experience during the first week of starting a ketogenic diet. Symptoms include headache, fatigue, brain fog, irritability, nausea, muscle cramps, and difficulty sleeping. It is caused by fluid and electrolyte loss as glycogen depletes, and by the body adapting its metabolism. To minimise keto flu: (1) Increase salt intake — add 2–3g sodium per day (e.g., salted broth, salt food generously). (2) Supplement potassium — eat avocados, spinach, or take a potassium supplement (1g/day). (3) Take magnesium — 300mg/day (magnesium glycinate or malate). (4) Drink plenty of water — at least 2–3 litres per day. (5) Ease into keto gradually rather than cutting carbs overnight. Most symptoms resolve within 7–10 days as the body becomes fat-adapted.

Q: How much protein should I eat on keto?

Protein intake on keto should be moderate — enough to preserve muscle mass without triggering gluconeogenesis (the conversion of protein to glucose). The recommended range is 1.2–2.0g of protein per kilogram of lean body mass per day. Active individuals and those lifting weights should aim for the higher end (1.7–2.0g/kg lean mass). Sedentary individuals can aim for 1.2–1.5g/kg lean mass. Getting protein right is critical: too little causes muscle loss and fatigue, while too much can raise insulin and potentially knock you out of ketosis. Lean body mass is calculated as total weight minus fat mass. For example, a 75kg person with 20% body fat has 60kg lean mass, so should eat 72–120g protein daily.

Q: Is the keto diet safe for people with diabetes?

The ketogenic diet can be effective for managing type 2 diabetes by significantly lowering blood glucose and reducing insulin resistance. Several studies have shown keto can lead to better HbA1c control than standard low-fat diets. However, people with type 1 diabetes or type 2 diabetes on insulin or sulphonylureas face serious risks: as blood sugar drops rapidly on keto, medication doses must be adjusted to avoid dangerous hypoglycaemia. People with type 1 diabetes also risk diabetic ketoacidosis (DKA). Anyone with diabetes MUST consult their GP or diabetologist before starting keto. Similarly, people with kidney disease should avoid high-fat, moderate-protein diets without medical supervision. People who are pregnant or breastfeeding should also seek GP advice first.

Q: What foods can I eat on a UK ketogenic diet?

Keto-friendly foods readily available in UK supermarkets include: Proteins — eggs, chicken, beef, pork, lamb, salmon, mackerel, sardines, prawns, full-fat Greek yoghurt. Fats — butter, ghee, double cream, olive oil, coconut oil, avocado, cheese (cheddar, brie, camembert), bacon. Low-carb vegetables — spinach, kale, broccoli, cauliflower, courgette, cucumber, celery, asparagus, mushrooms, cabbage. Nuts and seeds — walnuts, Brazil nuts, almonds, chia seeds, flaxseeds (in moderation). Avoid: bread, pasta, rice, potatoes, sugar, most fruit, beans, lentils, most dairy milk, beer, and standard fizzy drinks. Berries (raspberries, strawberries, blueberries) can be eaten in small amounts (50–80g). Always check labels — many 'healthy' UK products like granola bars, sauces, and flavoured yoghurts contain hidden sugars.

Updated February 2026 — Mifflin-St Jeor Formula

Calculate your personalised ketogenic macros — fat, protein and net carbs — based on your body measurements, activity level and keto goals.

Medical Disclaimer: The ketogenic diet may not be suitable for everyone. If you have diabetes (type 1 or type 2), kidney disease, liver disease, pancreatitis, or are pregnant or breastfeeding, please consult your GP before starting a ketogenic diet. Medication doses (especially insulin and sulphonylureas) may need adjustment. This calculator is for informational purposes only and does not constitute medical advice.

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Ketogenic Diet Type

What Is the Ketogenic Diet?

The ketogenic (keto) diet is a high-fat, moderate-protein, very low-carbohydrate eating pattern that shifts your body's primary fuel source from glucose to fat. When carbohydrate intake is restricted to approximately 20–50g of net carbs per day, your body depletes its glycogen stores and begins producing ketone bodies — acetoacetate, beta-hydroxybutyrate (BHB), and acetone — from fatty acids in the liver. This metabolic state is called nutritional ketosis.

Ketones are highly efficient fuel molecules that can cross the blood-brain barrier and power the brain, heart, and muscles. Many people report mental clarity, stable energy levels, and reduced hunger while in ketosis, as blood sugar swings are eliminated. The ketogenic diet was originally developed in the 1920s at the Mayo Clinic to treat childhood epilepsy, and has since gained widespread use for weight management, type 2 diabetes management, and metabolic health improvement.

How This Keto Calculator Works

This calculator uses the Mifflin-St Jeor equation — the most validated formula for estimating Basal Metabolic Rate (BMR) — to determine your daily energy needs:

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Your BMR is then multiplied by an activity multiplier (ranging from 1.2 for sedentary to 1.9 for extremely active) to calculate your Total Daily Energy Expenditure (TDEE). A calorie adjustment is then applied based on your goal: a 500 kcal deficit for weight loss, no adjustment for maintenance, or a 250 kcal surplus for lean bulking.

Keto macros are then distributed as follows for Standard Keto: approximately 70–75% of calories from fat, 20–25% from protein, and only 5% from carbohydrates. Protein targets are cross-checked against lean body mass (1.5–2.0g per kg lean mass) and the higher of the two values is used to protect muscle tissue.

Types of Ketogenic Diet

Standard Ketogenic Diet (SKD)

The most common approach: 70–75% fat, 20–25% protein, 5% carbohydrates. Net carbs are kept below 25–30g per day for most people. This is the best starting point for beginners and those focused on weight loss or metabolic health. It is also the type used medically for epilepsy management (at stricter ratios).

Targeted Ketogenic Diet (TKD)

TKD adds 20–30g of fast-digesting carbohydrates immediately before or during high-intensity exercise sessions. This provides glucose for muscle glycolysis during intense training while maintaining ketosis the rest of the time. Suitable for regular gym-goers and athletes who find pure SKD limits performance. On this calculator, TKD adds 25g net carbs to your daily total on training days.

Cyclical Ketogenic Diet (CKD)

CKD alternates between 5–6 days of strict standard keto and 1–2 days of high-carbohydrate refeeding (150–300g carbs). Carb refeeds replenish muscle glycogen, supporting higher training volumes. CKD is typically used by experienced athletes and bodybuilders. Note that carb refeeds will temporarily break ketosis — full re-entry to ketosis typically takes 1–2 days.

Net Carbs vs Total Carbs on Keto

On a ketogenic diet, you track net carbs, not total carbs. Net carbs are the carbohydrates that actually affect blood sugar and insulin levels. The formula is:

Net Carbs = Total Carbohydrates − Dietary Fibre − Sugar Alcohols (erythritol only)

Dietary fibre passes through the digestive system without being converted to glucose, so it does not count toward your carb limit. Most sugar alcohols (maltitol, sorbitol, xylitol) DO affect blood sugar and should be counted; erythritol is a notable exception and can generally be subtracted.

Common UK Keto Foods — Net Carb Reference

Food	Portion	Net Carbs	Keto Friendly?
Avocado	1 medium (150g)	2g	Yes
Cheddar cheese	30g	0g	Yes
Broccoli	100g	4g	Yes
Spinach (raw)	100g	1g	Yes
Salmon fillet	150g	0g	Yes
Eggs (whole)	2 large	0.5g	Yes
Almonds	30g	3g	Yes (in moderation)
Raspberries	80g	5g	Yes (in moderation)
Whole milk	200ml	9g	Limited
White bread	1 slice (35g)	15g	No
White rice (cooked)	100g	28g	No
Banana	1 medium	23g	No
Lentils (cooked)	100g	12g	No
Orange juice	200ml	22g	No

Keto Flu: Symptoms and How to Avoid It

During the first week of keto, many beginners experience what is commonly called keto flu — a collection of flu-like symptoms caused by fluid loss and electrolyte imbalance as glycogen stores deplete. Glycogen binds water at approximately 3g water per 1g glycogen, so losing 300–500g of glycogen results in 1–1.5 litres of rapid water loss, along with sodium, potassium, and magnesium.

Common keto flu symptoms: headache, fatigue, brain fog, muscle cramps, nausea, heart palpitations, irritability, difficulty concentrating, and poor sleep. Symptoms typically begin within 24–72 hours of starting keto and resolve within 7–10 days.

Prevention strategies: Increase sodium intake immediately (add pink Himalayan salt or sea salt to food, drink salted bone broth). Supplement magnesium glycinate (300mg before bed). Eat potassium-rich keto foods (avocados, salmon, spinach). Drink at least 2.5–3 litres of water daily. Reduce exercise intensity during the first two weeks. Consider gradually reducing carbs over 1–2 weeks rather than cutting immediately to 20g.

Keto and the NHS: What Does the Evidence Say?

The NHS acknowledges low-carbohydrate diets as a potential option for weight management and type 2 diabetes. NHS England's guidance on type 2 diabetes remission includes very low-calorie diets and, in some clinical settings, low-carb approaches. A 2021 review in the British Medical Journal found that low-carbohydrate diets were superior to low-fat diets for short-term weight loss and HbA1c reduction in type 2 diabetes, though long-term adherence can be challenging.

NICE guidelines (NG28) recommend the ketogenic diet as a treatment for drug-resistant epilepsy in children. The NHS also funds ketogenic dietary therapy through specialist centres for eligible patients with epilepsy.

For general population weight management, the NHS Eatwell Guide recommends a balanced diet that includes whole grains, fruits, and vegetables — this is not compatible with a ketogenic diet. However, NHS dietitians can support patients who choose to follow low-carbohydrate approaches, and the diet's evidence base for metabolic conditions continues to grow.

Keto for Weight Loss: How Much Can You Lose?

Weight loss on keto typically occurs in two phases. In the first week, rapid weight loss of 1–3 kg is common — this is almost entirely water weight from glycogen depletion, not fat. From week two onwards, with a 500 kcal daily deficit, sustainable fat loss of approximately 0.5 kg per week is realistic. Over a 12-week period, studies comparing keto to low-fat diets consistently show keto producing greater weight loss (approximately 2–4 kg more on average), largely due to reduced appetite from ketone-induced satiety and the protein-sparing effect of ketosis.

Frequently Asked Questions

How many carbs can I eat on keto?

On a standard ketogenic diet, aim for 20–50g of net carbs per day. Most people enter ketosis reliably at 20g net carbs or below. Net carbs are calculated as total carbs minus fibre. Targeted keto allows an extra 20–30g around workouts, and cyclical keto involves 1–2 high-carb days per week (150–300g).

What is ketosis and how long does it take to enter?

Ketosis is when your liver produces ketone bodies from fat for fuel. Glycogen stores deplete within 24–48 hours of strict carb restriction. Most people enter nutritional ketosis (blood ketones 0.5–3.0 mmol/L) within 2–7 days. Exercise speeds up the process — a glycogen-depleting workout can induce ketosis within 24 hours. Test with blood ketone metres for accuracy.

What is keto flu and how can I avoid it?

Keto flu causes headache, fatigue, muscle cramps, and brain fog during the first week, due to fluid and electrolyte loss. Prevent it by adding 2–3g sodium per day (salted broth), supplementing potassium (1g/day) and magnesium glycinate (300mg/day), drinking 2.5–3 litres of water daily, and reducing exercise intensity during the first two weeks.

How much protein should I eat on keto?

Aim for 1.2–2.0g protein per kilogram of lean body mass. Active individuals and those weight-training should aim for 1.7–2.0g/kg lean mass. Too little protein causes muscle loss; too much can raise insulin and kick you out of ketosis through gluconeogenesis. Lean body mass = total weight × (1 − body fat %).

Is the keto diet safe for people with diabetes?

Keto can improve type 2 diabetes markers, but anyone on insulin or sulphonylureas must consult their GP first — rapid blood sugar drops require medication dose adjustment to avoid dangerous hypoglycaemia. Type 1 diabetics risk diabetic ketoacidosis (DKA). People with kidney disease, liver disease, or who are pregnant should also seek medical advice before starting keto.

What foods can I eat on a UK ketogenic diet?

Keto-friendly UK foods: eggs, chicken, beef, salmon, mackerel, prawns, cheese, butter, double cream, avocado, olive oil, spinach, kale, broccoli, courgette, cauliflower, mushrooms, walnuts, almonds. Avoid: bread, pasta, rice, potatoes, most fruit, beans, lentils, beer, sugary drinks, and most sauces (check labels for hidden sugars).

Can the ketogenic diet help with epilepsy?

Yes. The NHS and NICE both recognise the ketogenic diet as a treatment for drug-resistant epilepsy, particularly in children, when two or more anti-epileptic drugs have failed. About 50% of patients see a greater than 50% seizure reduction. The medical keto diet (3:1 or 4:1 fat ratio) is strictly supervised by NHS dietitians and should not be self-administered.

Mustafa Bilgic Health & Nutrition Calculator Specialist, UK Calculator

Mustafa specialises in evidence-based nutrition calculators for UK audiences, drawing on peer-reviewed research and NHS clinical guidelines to ensure accuracy and safety.

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