Keto diet: how to do it step by step (and when it may or may not be suitable for you)

The ketogenic diet, or “keto,” has gained popularity in recent years, and with good reason. When done properly, it can become a highly powerful therapeutic tool for restoring energy, mental clarity, and metabolic balance. But it can also become a mistake if applied without discernment, without addressing the body’s real needs, or without a clear physiological basis.

This article aims to introduce you, in a rigorous yet accessible way, to the keto world. We will analyze what it is, for whom it may be useful (and for whom it may not), and when and how to carry it out step by step, without improvisation, adapting it to you and not the other way around.

The ketogenic diet consists of drastically reducing carbohydrates (normally between 20 and 50 net grams per day, although this depends greatly on the person’s situation), increasing healthy fats, and maintaining a moderate intake of protein. This change allows the body to enter nutritional ketosis: a metabolic state in which we stop using glucose as the main source of energy and begin using ketone bodies derived from fats.

This shift in fuel can have benefits for people with chronic fatigue, brain fog, appetite-regulation imbalances, or mitochondrial dysfunction. But it is not a magic, universal solution and should not be applied without taking into account the state of the digestive, nervous, hormonal, and immune systems.

What matters: Keto is not a diet without vegetables or a strategy for everyone. It is a fuel shift that can help you if it is adapted to your physiology.

Did you know...? During ketosis, the liver produces three types of ketone bodies: acetone, acetoacetate, and beta-hydroxybutyrate. The latter is the main responsible factor for the stable energy and mental clarity that many people experience on a keto diet.

From an integrative health perspective, keto may help you if:

• You have poor glucose regulation or insulin resistance.
• You experience a constant feeling of fatigue (or mitochondrial fatigue).
• You want to modulate chronic low-grade inflammation.
• You experience sugar cravings or constant hunger that does not feel satiating.
• You are looking for mental clarity and sustained energy without spikes and crashes, to improve cognitive focus.

The key point: The keto diet can help you if you are at a stage in life where you need to regulate your energy, modulate inflammation, and reconnect with your satiety signals. But it is not a one-size-fits-all solution.

Did you know...? The keto diet was originally developed as a treatment for refractory epilepsy in children. Over time, it has been shown to have regulatory effects on the nervous system, inflammation, and metabolism, even in healthy adults.

There are situations where following a keto diet can worsen your health:

If there is adrenal fatigue or hyperactivation of the sympathetic nervous system.

If you have liver or gallbladder problems, since fat metabolism will be more complex.

If your microbiota is highly imbalanced or there is severe dysbiosis, where a sudden reduction in fiber and certain nutrients can worsen the imbalance.

If you have a history of eating disorders.

If you are a woman of reproductive age and have low energy reserves, where it may compromise ovulation.

The key point: Not everyone is ready for a keto diet. Listen to your body and assess your hormonal, digestive, and emotional context before jumping in.

Did you know...? A drastic reduction in carbohydrates can affect the conversion of thyroid hormone T4 into T3, which can lead to fatigue, dry skin, or persistent cold if not properly monitored.

In women of reproductive age, it is essential to take hormonal context into account and respect the phases of the menstrual cycle, since the female body adjusts its energy needs accordingly.

During the follicular phase (especially in its first few days), the body usually tolerates a reduction in carbohydrates better, as energy demand is lower and hormone levels are still low.

As ovulation approaches, needs begin to increase, and after ovulation —in the luteal phase— the body needs more energy and carbohydrates to support progesterone production and promote a fertile environment.

If, during this phase, nutrients or calories are insufficient, the body may interpret that it is not a good time to reproduce and may downregulate ovulation in future cycles.

The important thing: If you are a woman of reproductive age, adapt the keto diet to your cycle. The key is to observe how the body responds; do not force a rigid model that your physiology is not ready to sustain.

Did you know...? The female body is programmed to prioritize survival. If it interprets that the environment is not safe or that nutrients are lacking, it may inhibit ovulation so as not to initiate a non-viable pregnancy.

Going abruptly from a carbohydrate-rich diet to a ketogenic one can trigger unpleasant adaptation symptoms: headache, irritability, fatigue, brain fog... It is better to do it gradually to avoid adaptation symptoms and allow the metabolism to reorganize without additional stress.

Prioritize non-starchy vegetables, such as leafy greens, zucchini, broccoli, mushrooms, cucumber, or eggplant. This way, you reduce carbohydrates without stopping feeding your microbiota.

What are 20-50 grams of net carbohydrates per day?

When we speak of “net carbohydrates,” we refer to total carbohydrates minus fiber. In other words, those that actually raise blood glucose and trigger metabolic responses.

Approximate examples of real foods:

• 1 cup of cooked broccoli (150 g): 4 g net
• 1 cup of raw spinach (30 g): less than 1 g net
• Half an avocado (100 g): 2 g net
• 1 cup of cooked zucchini (120 g): 3 g net
• 10 raspberries (20 g): 1 g net

A well-formulated keto diet can perfectly include five to eight generous servings of vegetables per day, as long as they are chosen well. It is not a diet without vegetables, but without flour, without refined starches, and without added sugars. But yes, with fiber, volume, color, and nutrients.

The important thing: Make the transition little by little and always prioritize real vegetables. Keto does not mean eating only meat and fat.

Did you know...? The intestine takes a few days to adapt to a new type of fuel. During that time, you may feel slower or low on energy. It is temporary.

The source of fat matters (a lot), but not just anything will do. Choose high-quality fats and avoid processed meats, industrial cream, or hydrogenated fats.

Recommended sources:

• Extra virgin olive oil
• Avocado
• Oily fish (sardines, mackerel, anchovies)
• Egg yolk
• Activated nuts (almonds, walnuts, macadamias)
• Ghee or grass-fed butter (if tolerated)
• Olives

If you experience heavy digestion, nausea, or a feeling of sluggishness, your liver or gallbladder may need support. In these cases, it is useful to include bitter foods such as arugula, endive, or liver-supporting infusions, and to consider the use of digestive enzymes.

What matters: It is not about eating fat for the sake of eating fat. It is about choosing fats that nourish your body and reduce inflammation.

Did you know...? Avocado is one of the most ketogenic foods there is: rich in monounsaturated fat, fiber, and potassium, and very low in net carbohydrates.

Excess protein can slow ketosis, because the body converts part of those amino acids into glucose (gluconeogenesis). But you should not go too low either. The key is balance.

Use organic eggs, high-quality meats, oily fish, and seafood as a base. You can supplement with hydrolyzed collagen if you have digestive weakness or want to support skin, joints, and mucous membranes.

What matters: You do not need to restrict essential proteins. Just balance them according to your needs.

Did you know...? Gluconeogenesis is a completely normal metabolic process, but if it is stimulated excessively it can take the body out of ketosis.

A well-designed keto diet is not a fiber-free diet. Gut bacteria also need nourishment, and fiber is key to regulating inflammation, improving bowel transit, and maintaining microbial diversity.

Include non-starchy vegetables, mushrooms, seaweed, and fermented foods, as well as seeds such as chia and flaxseed (soaked). And yes, you can also have raspberries or blueberries in small amounts.

The important thing: Reducing carbohydrates does not mean stopping feeding your gut microbiota. Fiber is your ally in caring for your digestive, nervous, and immune systems.

Did you know...? Green beans, although they are legumes, behave nutritionally like low-carbohydrate vegetables. Perfect for keto!

During the first days of ketosis, the body eliminates more water and with it important minerals are lost: sodium, potassium, and magnesium. This can lead to symptoms such as fatigue, cramps, irritability, or brain fog.

To prevent this:

• Drink plenty of water with unrefined sea salt or seawater (already potable, ready for consumption, and in very small amounts)
• Include mineral broths (vegetable or bone)
• Use remineralizing herbal infusions
• Consider using supplements if symptoms persist

Did you know...? Many of the symptoms of the so-called “keto flu” are not due to ketosis itself, but to a lack of electrolytes.

The important thing: Ketosis does not have to be uncomfortable if you hydrate and remineralize properly. Do not underestimate the power of a good broth.

After starting a keto diet, the first weeks of transition can be challenging. The body changes fuel, the liver works harder, and hormones rebalance. Be patient.

During this period it is common to experience:

• Fatigue or physical weakness
• Headache
• Changes in appetite
• Mood changes
• Difficulty sleeping

Support the process with hydration, rest, real foods, good routines, and without forcing it.

The important thing: Give the body time. It is not just a diet, it is a profound metabolic shift.

Did you know...? During adaptation, some people dream about bread or sweets. That is normal: the brain is reprogramming how it obtains energy.

It is not only what you eat that matters, but when and how you eat it. The regulation of insulin, leptin, cortisol, and ketone bodies is strongly influenced by the circadian rhythm.

Eating at consistent times, having an early dinner (ideally before daylight fades), and sleeping well improves metabolic efficiency and energy flexibility, promoting ketosis and facilitating cellular repair.

The important thing: Keto starts with how you live, not just with what you eat. Your biological clock matters too.

Did you know...? Nighttime ketosis is more efficient if you avoid large meals at night. Sleeping in a mild fast supports brain regeneration.

The ketogenic diet can be adjusted to the type of exercise performed:

• In long-duration aerobic efforts (running, walking, or swimming), it may improve performance, as the body uses fat as its main energy source.
• In intense or explosive training sessions, you may need strategic carbohydrates after exertion (for example, after exercise or on specific days).

It is not cheating, it is metabolic intelligence. There is no single way to do keto, and it must be adapted to the reality of each body and lifestyle.

The important thing: Adapt keto to your activity level, not the other way around. More movement, more flexibility.

Did you know...? The body can adapt to using ketone bodies even during exercise, but it requires weeks (or months) of adaptation.

Don’t become obsessed with being in ketosis. What matters is how you feel: sustained energy, good digestion, mental clarity, restful sleep, and satiety without anxiety.

If you are only focused on the number shown by a test strip, you will lose sight of what is essential.

What matters: Fewer numbers, more sensations. If you feel well, you are on the right track.

Did you know...? You can be in ketosis without the strip detecting it. Breathing patterns, breath, and energy efficiency are also reliable signs.

The short answer is: no. The long answer is: it depends on your body, your goals, and your stage of life. Keto can be a wonderful tool to gain energy, clarity, and regulate certain functions, but that does not mean you have to live in ketosis forever.

Many people benefit more from a cyclical approach: periods of ketosis interspersed with phases where carbohydrates are strategically reintroduced, depending on exercise, the menstrual cycle, rest, or stress.

The ultimate goal is not to be “on a diet,” but to develop something much more powerful: metabolic flexibility. That is, for your body to know how to use both glucose and ketone bodies according to what it needs at any given moment. That is health.

Did you know...? Hunter-gatherers naturally lived in a state of intermittent ketosis. Not because they followed a keto diet, but because their food resources changed with the seasons and availability. Flexibility was the norm.

The keto diet is not a universal model, but it can be a very useful tool if applied well. It can help you if you use it with purpose: without improvising, without copying what worked for someone else, and without forgetting your microbiota, your rest, your cycle, and your nervous system.

The goal is not to eliminate a food group, but to generate a specific metabolic response that helps you recover balance, energy, and long-term health. Because it is not about eating fewer carbohydrates, it is about taking better care of your health.

It is not about being in ketosis all the time, but about teaching your body to adapt. The real goal is for you to be able to use any fuel... and feel good doing it.