Ketogenic Diet (Keto): The Complete Scientific Guide

David Diaz Gil 8 min. of reading Diets Leave a comment

If you’ve been in the fitness world for a while, you’ve probably heard about the keto diet beyond the typical “lose 5 kilos in a week” promises.

The truth is that, although it became popular as a **fat-loss method**, the ketogenic diet is actually a metabolic tool with a solid scientific foundation, used by both performance athletes and in clinical settings for decades.

In this article, we’ll break down what really happens in your body when you enter ketosis, which benefits are supported by scientific evidence, and how to structure a ketogenic meal plan without making the process miserable.

What Is the Ketogenic Diet and How Does Ketosis Work?

The keto diet is based on a simple principle: **if we drastically reduce carbohydrate intake (usually below 50g per day), the body runs out of its preferred fuel source—glycogen.**

Within about 2–4 days, liver glycogen stores become depleted, and the liver activates a process called **ketogenesis**: it begins converting fatty acids into molecules known as ketone bodies, the most important of which is beta-hydroxybutyrate (BHB). These ketone bodies enter the bloodstream and become the new **energy source for the brain, heart, and muscles**.

Essentially, you’ve “reprogrammed” your metabolism to run primarily on fat.

Differences Between Nutritional Ketosis and Ketoacidosis

This is an important distinction because it’s one of the most widespread misconceptions. **Nutritional ketosis is a completely natural and safe metabolic state**, where blood ketone levels remain within a controlled range (between 0.5 and 3 mmol/L).

**Ketoacidosis**, on the other hand, is a **serious medical emergency** that occurs almost exclusively in people with untreated type 1 diabetes. In this condition, ketone levels rise uncontrollably (above 15–20 mmol/L) along with a dangerous acidification of the blood.

These processes share a similar name, but **they are entirely different in terms of safety.**

Science-Backed Benefits of the Keto Diet

Beyond trends and hype, the ketogenic approach is supported by a substantial body of research demonstrating **benefits across multiple areas:**

Weight Loss, Satiety, and Hormonal Optimization

One of the most studied effects of the ketogenic diet is its impact on appetite control. Ketones, together with a higher intake of fats and proteins, **help regulate hormones related to hunger**:

Reduce ghrelin (the hormone that stimulates hunger).
Increase leptin (the hormone that signals fullness).

The practical outcome is that many people experience a **natural calorie deficit** without the constant feeling of hunger commonly associated with other restrictive diets. In addition, several studies point to **improved insulin sensitivity**, which is particularly relevant for those looking to optimize body composition.

Athletic Performance and Metabolic Flexibility

This is where a key concept comes into play: metabolic flexibility, meaning the **body’s ability to efficiently switch between glucose and fat as fuel sources depending on current demands.**

For endurance athletes (ultra-runners, long-distance cyclists) and strength athletes during a cutting phase, this offers a clear advantage: by teaching the body to efficiently burn fat, muscle glycogen—which is always limited—can be **reserved for moments of maximum intensity, such as a final sprint or a set taken to failure.**

What Do You Eat on a Keto Diet?

The key to a well-designed keto diet isn’t simply removing carbohydrates—it’s building the diet around **clean, high-quality foods**. We’re talking about:

Healthy fats: extra virgin olive oil, avocado, nuts, coconut oil
High-quality proteins: eggs, oily fish, meat, aged cheeses
Low-carbohydrate vegetables: leafy greens, broccoli, zucchini, asparagus
Functional fats: MCTs, butter from grass-fed animals

The goal isn’t simply to “eat bacon and cheese without limits,” but rather to design meals that **provide nutritional density while keeping macronutrients within the ketogenic range** (typically 70–75% fat, 20–25% protein, and 5–10% carbohydrates).

How to Get Started and Structure a Ketogenic Meal Plan

The first—and probably most important—step is planning. Ketosis is a metabolic state that can be easily disrupted if we don’t keep at least an approximate track of the **carbohydrates consumed throughout the day**.

We recommend:

Calculate your macros before starting—don’t just guess.
Plan your meals in advance, especially during the first few weeks.
Always read labels: hidden carbohydrates (sauces, dressings, processed foods) are the number one reason many people fail to enter ketosis.
Start with simple meals and gradually add variety.

Supplementation on a Keto Diet

Supplementation isn’t mandatory on a ketogenic diet—it is entirely possible to follow a well-planned keto diet using only whole foods. However, supplements can act as an accelerator and, in some cases, a real lifesaver during the first few days.

MCT Oil, Electrolytes, and Whey Protein

MCTs (Medium-Chain Triglycerides): These are fats that the liver can convert directly into energy and ketones without requiring the longer digestive process needed for other fats. That’s why they’re so popular among keto followers, providing a “fast fuel” source that is fully compatible with ketosis. You can try Powdered MCT Oil.
Electrolytes (Sodium, Magnesium, Potassium): When carbohydrate intake decreases, insulin levels also drop, causing the kidneys to excrete more sodium (and therefore more water). Replenishing these electrolytes is essential to maintain osmotic balance and avoid many of the uncomfortable symptoms experienced at the beginning of the diet. You can add one serving of Evolytes Powder to a 500ml bottle of water.
Whey Protein: High-quality protein remains essential for preserving muscle mass, but on a keto diet its macronutrient profile should fit the context. That’s why an option like Keto Whey Protein, with added fat ratios specifically designed for keto, can help meet protein requirements without disrupting daily macro targets.

The “Keto Flu” and How to Prevent It

If during the first two weeks you experience **headaches, fatigue, muscle cramps, or brain fog**, don’t panic. This is commonly known as the “keto flu,” one of the most common (and most feared) side effects when starting a ketogenic diet.

The explanation is the same as mentioned earlier: as insulin levels drop rapidly, the kidneys **excrete significantly more sodium and water than usual**, creating the combination of symptoms many people experience.

The good news is that it’s easy to prevent:

Increase your salt and electrolyte intake from day one—don’t wait until symptoms appear.
Stay hydrated more than usual.
Avoid very high-intensity training during the first adaptation week.
Be patient: in most cases, symptoms disappear within 3–7 days as your body adapts to using fat as its primary fuel source.

Ready to give the ketogenic diet a try? As with any major dietary change, we recommend consulting a healthcare professional before starting, especially if you have any pre-existing medical conditions.

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