I can share my personal experience, even though it’s obviously not a one-size-fits-all solution.
I had never been on a diet in my life and had always been fairly slim and fit. Last year, after two surgeries, I had to stay in bed for several months. Between the inactivity and comfort eating, I gained weight like never before. I genuinely felt like I’d never get my body back.
Other factors prompted me to try the
ketogenic diet: I was constantly tired, prone to cravings, migraines, and brain fog, and I also have an autoimmune disease. So I wondered if this diet might help me.
Today, after four months on the ketogenic diet, my experience has been very positive: I’ve lost weight, regained more stable energy levels, and learned to better recognize when I’m hungry. I no longer see it as a temporary diet, but as a way of eating that I’ve gradually incorporated into my life. The benefits I’ve gained are such that I can’t imagine going back to my old eating habits.
Before you begin, however, I recommend doing thorough research. It’s not simply a matter of cutting out bread or pasta, but of making profound changes to the composition of your meals. You should also make sure this diet is compatible with your health condition. If you have diabetes, a specific medical condition, are taking medication, or have kidney, liver, or eating disorders, it’s best to work with a doctor or dietitian trained in this approach.
In practical terms, the ketogenic diet involves drastically reducing carbohydrates, maintaining an adequate protein intake, and meeting the remainder of your energy needs with fats. You generally eat protein-rich foods, fats, and low-carb vegetables, particularly leafy greens.
This diet aims to induce nutritional ketosis. The body then relies more on fatty acids and ketone bodies as energy sources, rather than depending primarily on glucose. Ketone bodies are not fat themselves; they are produced mainly by the liver from fatty acids.
The transition was fairly natural for me, but the first few days were difficult. For three or four days, I had severe migraines and very little energy. This corresponds to what is commonly called the “keto flu,” a set of temporary symptoms that can accompany a sudden reduction in carbohydrates and the loss of water and electrolytes. It’s therefore important to make sure you drink enough fluids and properly replenish your electrolyte levels.
Since I had never counted calories or macronutrients before, I used ChatGPT as a learning tool after providing it with PDF resources and a good, concise prompt. I would tell it what was in my cupboards and refrigerator. It would suggest meals with the quantities of each food item, then recalculate the nutrient intake based on any changes I made.
For six to eight weeks, I weighed my food and checked my protein, fat, and carbohydrate intake daily. Today, I no longer need to do that: I’ve internalized the portion sizes and know how to put together my meals. ChatGPT can, however, make mistakes. I consider it a helpful tool and not a substitute for a healthcare professional.
I lost weight fairly quickly at first. Much of that initial weight loss was due to water loss: as glycogen stores decrease, the water associated with them also decreases. Fat loss then proceeded more gradually.
I didn’t need to cut back on my fat intake - it actually increased, since my previous diet was very high in grains and rather low in fat. That doesn’t mean you can eat unlimited amounts of butter, cream, cheese, or oil. Fat intake should still be tailored to your hunger, physical activity, and your specific goal.
Ketosis promotes the use of fat as fuel, but it does not automatically guarantee body fat loss. If calorie intake exceeds energy needs, you can remain in ketosis without losing weight. One of the benefits of this diet is that, for some people, it can reduce hunger and naturally encourage eating in line with their needs.
It is also important to maintain an adequate protein intake and, if possible, to engage in strength training to preserve muscle mass during and after weight loss.
I didn’t set a specific weight loss goal or a deadline for myself. I simply continued eating this way, and my body gradually became slimmer.
One of the main benefits, in my case, was better control over my hunger and energy levels. I no longer experience the same cravings or those intense bouts of fatigue after meals. I naturally started eating twice a day instead of three times, without forcing myself. However, this is neither a requirement nor an essential condition for being in ketosis.
The book (in French) that helped me the most is
Le Grand Livre de l’alimentation cétogène by Nelly and Ulrich Génisson. It covers the basics of this diet and includes many recipes.
That’s my experience.
The ketogenic diet isn’t for everyone, and I don’t claim it’s the only right way to eat.
Nevertheless, I find it fascinating that the human body is so metabolically flexible. This ability is part of our physiology and our evolutionary history. Just think for a moment about what we ate before the adoption of agriculture around 10,000–12,000 BC! Sure, people were already eating honey, tubers, and fruits, but these two last were significantly less sweet than they are today - since they, too, have been transformed over the millennia into the products we produce today - and the quantity and variety were also much smaller back then. That really makes you think, doesn’t it!?

That’s yet another fascinating topic...