What Is the Keto Diet — And How Do You Calculate Your Keto Macros?

The ketogenic diet is one of the most searched dietary approaches in the world — and also one of the most misunderstood. This guide explains exactly what keto is, how it works, what your daily macros should look like, and how to calculate the right targets for your body weight and goals. Whether you are considering keto for weight loss, blood sugar control, or general health, this is what the evidence actually shows.

What Is the Keto Diet?

The ketogenic diet is a very low-carbohydrate, high-fat diet that shifts your body’s primary fuel source from glucose (sugar) to ketones — molecules produced by the liver from fat. This metabolic state is called ketosis.

Under normal dietary conditions, your body runs primarily on glucose derived from carbohydrates. When carbohydrate intake drops below approximately 20–50g per day, glucose availability falls low enough that the liver begins converting fatty acids into ketone bodies — which your brain, muscles, and organs then use as an alternative fuel source.

This shift takes 2–7 days to establish, depending on your current glycogen stores, activity level, and individual metabolic response. Once in ketosis, many people report reduced hunger, more stable energy levels, and — for those seeking weight loss — a natural reduction in calorie intake driven by improved satiety.

Standard Keto Macro Ratios

The classic ketogenic macro split is:

• Fat: 70–75% of total daily calories
• Protein: 20–25% of total daily calories
• Carbohydrates: 5–10% of total daily calories (typically 20–50g net carbs)

These ratios are starting points, not fixed rules. Individual responses to carbohydrate vary — some people maintain ketosis at 50g net carbs, others require below 20g. Activity level also matters: athletes doing high-intensity training may need to adjust protein upward and can sometimes tolerate slightly more carbohydrate around training.

How to Calculate Your Keto Macros

Calculating keto macros requires three steps: finding your total daily calorie target, setting your carb limit, then distributing the remaining calories between fat and protein.

Step 1 — Find Your Daily Calorie Target

Your keto macro targets are built on top of your Total Daily Energy Expenditure (TDEE) — the total calories your body burns each day. Use our calculator to find your TDEE, then adjust based on your goal:

• Weight loss: TDEE minus 300–500 kcal
• Maintenance: TDEE (no adjustment)
• Muscle gain: TDEE plus 200–300 kcal

Step 2 — Set Your Carb Limit

For most people starting keto, the target is 20–25g net carbs per day — conservative enough to reliably produce ketosis regardless of individual variation. Once fat-adapted (typically 4–6 weeks), some people can increase to 30–50g net carbs and remain in ketosis.

Carbohydrates provide 4 kcal per gram. At 20g net carbs, this is 80 kcal from carbohydrates — approximately 4–5% of a 1,800 kcal daily target.

Step 3 — Set Your Protein Target

Protein on keto is often under-emphasised. Adequate protein is essential for preserving muscle mass, especially during weight loss. The target for most people on keto is 1.2–1.7g of protein per kg of body weight — or approximately 0.6–0.8g per pound.

Common concern: can too much protein “kick you out of ketosis” through gluconeogenesis? The evidence does not support this for most people at normal protein intakes. Prioritise protein — inadequate protein on keto causes muscle loss, not deeper ketosis.

Step 4 — Fill Remaining Calories With Fat

After setting carb and protein targets, fat fills the remaining calories. Fat provides 9 kcal per gram — significantly more than carbohydrates or protein. This is why fat portions look large on keto: you need more volume of fat to hit your calorie target.

Keto Macro Targets by Body Weight — Quick Reference

The table below shows approximate keto macro targets for weight loss at different body weights, assuming a moderate activity level and standard 500 kcal deficit from TDEE.

What to Eat on Keto — and What to Avoid

Keto-Friendly Foods

• Meat and poultry: Beef, chicken, pork, lamb, turkey — all are essentially zero carb
• Fish and seafood: Salmon, mackerel, sardines, tuna, prawns — also excellent sources of omega-3
• Eggs: One of the most keto-friendly foods — approximately 0.5g carbs per egg
• Full-fat dairy: Butter, hard cheese, heavy cream, Greek yoghurt (plain, full-fat) — check labels for carb content
• Low-carb vegetables: Spinach, kale, broccoli, courgette, cauliflower, peppers, cucumber, avocado
• Nuts and seeds: Almonds, walnuts, pecans, macadamia nuts, chia seeds, flaxseed — in moderate portions
• Healthy oils: Olive oil, coconut oil, avocado oil, butter, ghee

Foods to Avoid on Keto

• Grains and starches: Bread, pasta, rice, oats, cereals, crackers
• Sugar and sweets: All forms — table sugar, honey, maple syrup, sweets, chocolate (except 85%+ dark)
• Most fruit: Bananas, apples, grapes, mangoes, oranges — too high in fructose. Berries (strawberries, raspberries, blueberries) in small amounts are acceptable
• Starchy vegetables: Potatoes, sweet potatoes, parsnips, corn, peas
• Legumes: Beans, lentils, chickpeas — moderate to high carb
• Alcohol: Beer and sweet wine are high-carb; dry wine and spirits are lower-carb but still suppress ketosis temporarily

Does Keto Work for Weight Loss?

The evidence for keto and weight loss is strong in the short term and more mixed in the long term. Key findings from the research:

• Keto consistently produces greater weight loss than low-fat diets at 6 months — typically 2–3 kg more
• At 12 months, differences between keto and other calorie-restricted diets largely disappear — adherence becomes the dominant factor
• Keto is particularly effective for people with type 2 diabetes or insulin resistance, producing significant improvements in blood sugar control beyond weight loss alone
• The rapid initial weight loss on keto (often 2–4 kg in the first two weeks) is largely water and glycogen — each gram of glycogen is stored with approximately 3g of water

The honest conclusion: keto works well for weight loss for people who can adhere to it. It is not uniquely metabolically superior to other deficit-based approaches at equivalent calorie levels — but many people find its appetite-suppressing effect makes adherence easier.

Who Should and Should Not Try Keto

Keto May Be Worth Trying If You:

• Struggle to control hunger on higher-carbohydrate diets
• Have type 2 diabetes or prediabetes and want to improve blood sugar control (consult your GP first)
• Have tried other dietary approaches without sustained success
• Prefer eating high-satiety foods (meat, fish, eggs, cheese) over grains and starches

Keto Is Not Recommended If You:

• Have a history of kidney stones or kidney disease (high protein load requires medical supervision)
• Have a history of pancreatitis (high fat intake can trigger episodes)
• Are pregnant or breastfeeding
• Have type 1 diabetes (ketosis and diabetic ketoacidosis require careful medical management)
• Take medications for diabetes or blood pressure (keto may require medication adjustments — always consult your GP)

Frequently Asked Questions

The Bottom Line

The ketogenic diet is a legitimate, evidence-backed dietary approach for weight loss and blood sugar control — not a fad. It works by restricting carbohydrates low enough to induce ketosis, which suppresses appetite and shifts fat metabolism in meaningful ways.

Standard keto macros are approximately 70% fat, 25% protein, and 5% carbohydrates, built on top of your personalised calorie target based on TDEE. Most people starting keto should target 20–25g of net carbs per day, 1.2–1.7g of protein per kg of body weight, and fill remaining calories with healthy fats.

It is not the right approach for everyone — adherence is the single biggest predictor of long-term success, and a dietary pattern you can sustain for years will always outperform one you cannot maintain past three months. But for people who find low-fat, higher-carb approaches unsatisfying, keto is a well-supported alternative worth trying.