What is the ketogenic diet?
The ketogenic diet is an eating pattern that lowers carbohydrate to a very low level and makes fat the main energy source. About 70 per cent of daily energy comes from fat, 20-25 per cent from protein and only 5-10 per cent from carbohydrate; that usually means 20-50 grams of carbohydrate a day. When carbohydrate falls this low, the body starts using ketone bodies produced from fat as fuel instead of glucose. This state is called ketosis, and it is the mechanism the ketogenic diet takes its name from.
The ketogenic diet was first used in medicine, in the treatment of epilepsy; its spread in weight management is more recent. It is a powerful method, but its rules are strict and it is not suitable for everyone.
How does it work?
In normal eating, the body first burns the glucose that comes from carbohydrate. When carbohydrate is cut, the glycogen stores in the liver are used up in a day or two; then the liver starts producing ketones from fatty acids and all tissues, including the brain, use these ketones. The transition to ketosis usually takes 2-4 days. Tiredness, headache and weakness can be seen in this period (called "keto flu"); plenty of water and enough salt and magnesium ease these symptoms. Once in ketosis, appetite drops noticeably; a significant part of the weight loss comes from this drop in appetite and from the water lost in the first weeks.
What is eaten and what is not?
- Allowed: Meat, chicken, fish, eggs, butter, olive oil, avocado, cheese, clotted cream, walnuts, almonds, hazelnuts, green leafy vegetables, broccoli, cauliflower, courgette, cucumber, olives.
- Limited: Yoghurt (full fat, small amounts), low-sugar fruit such as strawberries and raspberries, tomato, onion.
- Not allowed: Bread, pasta, rice, bulgur, potatoes, legumes, sugar, honey, fruit juice, most fruit, desserts, sugary drinks.
Many traditional cuisines suit the ketogenic diet better than expected: grilled dishes, egg dishes, greens in olive oil, cheeses and nuts are the building blocks of this pattern. What is missing is only bread and rice.
A sample day
- Breakfast: A two-egg omelette cooked in butter, 2 slices of white cheese, half an avocado, olives, greens.
- Snack: A handful of walnuts or 30 grams of hard cheese.
- Lunch: Grilled chicken thigh, a large green salad with plenty of olive oil, 1 tablespoon of tahini.
- Dinner: Baked salmon or grilled meatballs, broccoli sautéed in butter, yoghurt with cucumber.
- Evening: Unsweetened herbal tea; a few olives if wanted.
Benefits
- Appetite drops noticeably; hunger between meals almost disappears.
- Fast and motivating weight loss is seen in the first weeks.
- Blood sugar fluctuations are minimised; sweet cravings decrease.
- Some users report mental clarity and steady energy.
Risks and points to watch
The ketogenic diet is a pattern that requires close monitoring. People taking diabetes medication, people with kidney or liver disease, pregnant and breastfeeding women, people with gallbladder problems and people with high cholesterol should start this diet only with a doctor's approval. Because water and minerals are lost in the first week, fluid and salt intake should be increased; because fibre decreases, green vegetables must not be left out. For most people the ketogenic diet is a short- to medium-term tool; after the goal is reached, a transition period in which carbohydrate is added back gradually and under control must be planned, otherwise the weight lost comes back quickly.
The 5 most common mistakes
- Missing "hidden" carbohydrates. Sauces, yoghurt, milk, fruit and some nuts can contain enough carbohydrate to break ketosis.
- Being afraid of fat. If fat is cut and protein increased, the body converts protein to glucose; ketosis does not occur.
- Fluid and mineral deficiency. The main cause of keto flu; water, salt and magnesium solve it.
- Neglecting green vegetables. Lack of fibre causes constipation; greens and broccoli should be on the list every day.
- Not planning the end. When carbohydrate is added back without control, the weight returns quickly; the transition period should be planned with a dietitian.
How is the ketogenic diet applied on Diet Prof?
Your calorie need is calculated with the free analysis; you state at the start that you prefer the ketogenic type, or send it from Dietitian Support. Your list is built according to the ketogenic balance of fat, protein and carbohydrate; the quantities and calories of every meal are on the meal card, and your shopping list is generated automatically. You replace a meal you do not like with another option that still fits the ketogenic balance using Change Meal. If you enter your test results (especially cholesterol, liver and kidney values) in your profile, the dietitian team reviews your list accordingly; when you reach your goal, the transition period is planned for you as well. The whole process is on the How Does Diet Prof Work? page.
Frequently asked questions
How do I know I am in ketosis?
Reduced appetite, a slight acetone smell on the breath and in urine, and the rapid water loss of the first week are typical signs. It can also be measured with urine ketone strips sold in pharmacies.
How long should it last?
For most people 4-12 weeks is a reasonable period; afterwards a gradual transition to a balanced diet is planned according to the goal. Long-term use requires doctor and dietitian follow-up.
Can I never eat fruit?
Low-sugar fruit such as strawberries, raspberries and blackberries can be included in small portions. High-sugar fruit such as banana, grapes and figs breaks ketosis.
Start now
Set up correctly, the ketogenic diet gives fast and strong results; set up wrongly, it is exhausting. Start with the free analysis, let your list be prepared to the ketogenic balance, and have the dietitian team beside you throughout.
