What is the ketogenic diet?
The ketogenic diet, also commonly known as the keto diet or keto diet, is a way of eating that reduces carbohydrate intake and increases fat intake , putting the body into a metabolic state known as ketosis. In recent years, this diet has gained increasing popularity.
There are several approaches to the ketogenic diet, each with variations in calorie content and the ratio of macronutrients, including carbohydrates, fats, and proteins.
The primary goal of this diet is to induce ketosis , a process by which the body burns fat for energy.
Ketosis is believed to aid weight loss and provide health benefits, such as lowering blood sugar and improving cholesterol.
What is ketosis?
Ketosis is a state in which the body uses fat as its primary source of energy , producing molecules called ketones.
Normally, the body relies on carbohydrates for energy, and insulin is responsible for storing blood sugar, called glucose, for this purpose. However, when carbohydrate intake is reduced, insulin levels drop, leading to a series of metabolic changes.
Initially, glucose is stored as glycogen in the muscles and liver, available for use when needed.
However, after a few days of low carb intake, these glycogen stores become depleted.
In this phase, the body begins to use stored fat as its primary source of energy. The breakdown of fat produces free fatty acids, which are converted in the liver into ketones, which the body can then use as fuel.
For example, intense physical activity can accelerate the consumption of glycogen stores, causing the body to enter a state of ketosis more quickly.
In conclusion, ketosis is a natural metabolic process that occurs when the body uses fat as its primary source of energy, producing ketones as a byproduct.
How does the ketogenic diet work?
Reducing carbohydrate intake in the diet also reduces insulin production, which can have significant health benefits, especially in people who consume excessive amounts of high-glycemic carbohydrates, which are foods that raise blood sugar levels excessively when eaten.
Despite the weight loss, low blood sugar, and high blood ketones, some studies have raised concerns about the long-term effects of the ketogenic diet.
For example, one study in rats showed that sustained adoption of a keto diet for 60 days caused side effects such as metabolic acidosis , anemia , and reduced levels of antioxidant enzymes in the blood .
These findings indicate that while the ketogenic diet may offer initial benefits, it is essential to carefully consider potential risks and monitor long-term health while adopting this dietary regimen.
Classic Ketogenic Diet
The classic ketogenic diet (known as cKD) has been used since 1921 to treat epilepsy in children.
This type of diet is called "classic" because it was the first to be developed and used. The cKD is a diet that provides a normal caloric intake but is high in fat and low in carbohydrates.
It is used worldwide to treat drug-resistant epilepsy, when conventional drugs do not work.
cKD has been shown to have anticonvulsant effects, meaning it helps prevent or reduce seizures.
This effect is achieved by shifting the main source of calories from carbohydrates to fats. In practice, the diet is composed mainly of fats, with a limited amount of protein and carbohydrates.
A common ratio is 4 parts fat to 1 part protein and carbohydrates combined.
Variations of the ketogenic diet
- Ketogenic hyperlipidic and hyperprotein (like the Atkins diet)
- Ketogenic hyperlipidic and normo-hypoprotein (such as the modified Atkins diet for the treatment of drug-resistant epilepsy)
- Low-fat, normoprotein ketogenic diet (such as VLCKD, used to treat obesity).
Ketogenic Diet: The Extremely Low-Calorie Variant
A very popular variant of the ketogenic diet is the very low calorie ketogenic diet (VLCKD), which has recently been suggested as a dietary strategy for managing obesity.
This type of diet is characterized by a low carbohydrate intake, with less than 50 grams per day, and a moderate amount of protein, usually around 1-1.5 grams per kilogram of ideal body weight. As for fats, the daily intake is around 15-30 grams.
It is important to note that this diet provides a very low calorie intake, usually between 500 and 800 calories per day. This diet aims to promote ketosis and weight loss through calorie restriction and the elimination of carbohydrates.
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GO TO THE NUTRITIONAL TESTContraindications of the Keto diet
In recent years, the ketogenic diet has gained considerable popularity, especially among those seeking to lose weight and reduce insulin resistance in both type 1 and type 2 diabetes.
However, there are concerns about the long-term effectiveness in weight loss and the potential adverse effects on kidney function and blood cholesterol levels due to increased protein and fat intake.
Particularly in the case of diabetes, increased intake of animal protein, but not plant protein, has been associated with insulin resistance and increased health risk.
Additionally, foods rich in animal protein also contain other nutrients, such as saturated fat, heme iron, and nitrites, which may contribute to these results.
Additionally, high-protein diets are linked to compounds produced by protein fermentation by the gut microbiota, which may include pro-inflammatory metabolites.
Side effects
In the short term, it is common to experience some symptoms while transitioning to a ketogenic diet.
These may include easy fatigue during exercise, reduced mental energy, increased hunger, trouble sleeping, muscle cramps, constipation, bad breath, nausea, and stomach pain.
However, most of these complaints tend to decrease after the first few days of adaptation.
Ensuring adequate fluid and electrolyte intake can help counteract some of these symptoms. Long-term adverse effects include:
- Nutritional Deficiencies : Keto diets are very restrictive and can lead to nutritional deficiencies with inadequate intake of essential vitamins, minerals, and phytochemicals.
- Digestive problems : High-fat, low-fiber diets can cause digestive problems, such as constipation, diarrhea, and bloating .
- Kidney stones : A high-fat, low-carb diet may increase your risk of developing kidney stones.
- Heart disease : A ketogenic diet may increase your risk of heart disease due to its high saturated fat content and lack of fiber.
- Muscle Loss : Rapid weight loss on a ketogenic diet can lead to muscle loss, negatively impacting athletic performance.
- Cognitive decline : The effects of low-carb diets on brain metabolism can potentially lead to cognitive decline.
It is important to note that, although the ketogenic diet may offer benefits in improving fat utilization capacity, especially in endurance sports, some authors suggest that high-level athletic performance may not be optimal in the absence of adequate carbohydrate intake.
This demonstrates the importance of carefully assessing individual needs and finding a balance between ketosis adaptation and the specific demands of physical activity.
When it is not recommended to follow the ketogenic diet
According to recent studies, during pregnancy and breastfeeding, women should prudently avoid following a ketogenic diet.
This is because a negative effect on cognition has been observed in rodents exposed to ketosis during early life through young adulthood.
However, it is important to note that no adverse neurodevelopmental effects have been found in children who used a ketogenic diet to treat epilepsy.
Categories of people for whom a ketogenic diet may not be recommended include:
1. People with severe liver or kidney disease: Because the ketogenic diet can affect lipid and carbohydrate metabolism, it may not be safe for those with liver or kidney problems.
2. Pregnant or breastfeeding women: During pregnancy and breastfeeding, the body has specific nutritional needs that may not be adequately met on a ketogenic diet.
3. People with eating disorders: Calorie restrictions and a focus on certain food groups may exacerbate problems for those with eating disorders such as anorexia or bulimia.
4. Individuals with certain medical conditions: Some medical conditions, such as type 1 diabetes, may require more careful adjustment of the diet, and a ketogenic diet may not be right for everyone.
Ketogenic diet pros and cons
The ketogenic diet involves severely restricting carbohydrates, while allowing ample intake of fats, including saturated fats. This diet has attracted a great deal of interest, with many proponents and just as many opponents.
While the ketogenic diet can lead to rapid and significant weight loss and improvements in biomarkers, such as reduced glycated hemoglobin in patients with type 2 diabetes, it can also cause significant increases in levels of “bad” LDL cholesterol , a fact that makes many doctors hesitant to promote it.
In addition, two human studies have highlighted potential harmful effects of ketone bodies. In a general population-based cohort study, individuals aged 54 ± 12 years, a positive correlation was found between circulating ketone bodies and all-cause mortality.
It turned out that increased mortality was also linked to an increase in liver fat index, a marker of non-alcoholic fatty liver disease, and this relationship was partly mediated by circulating ketone bodies .
Another study reported a dose-response relationship between increased body ketone concentrations and a 50% increase in all-cause mortality among black and white Americans.
Although the ketogenic diet has traditionally been considered beneficial for weight and glucose control, with few side effects and good adherence and tolerance even in the elderly, concerns arise regarding its health consequences.
The main problem is the variation in versions of the ketogenic diet and the different effects of its essential components. Consequently, the consequences of the ketogenic diet may extend beyond the action of circulating ketone bodies.
How long can you do the ketogenic diet?
According to most authors, the ketogenic approach should be understood as a time-limited diet . Long-term adherence to a ketogenic diet can be a challenge.
Although this diet has demonstrated positive results in inducing rapid and sustained weight loss in obese individuals for up to two years, it is essential to fully understand its clinical impact, safety, tolerability, efficacy, duration of treatment, and long-term prognosis after its discontinuation.
The length of the ketogenic diet can vary considerably, from as little as 2-3 weeks to as long as 6-12 months , according to the National Library of Medicine.
During this time, it is crucial to carefully monitor kidney function, given the changes in water metabolism and diuresis associated with the reduction in glycogen levels during a ketogenic diet, it is advisable to increase fluid intake to maintain water and electrolyte balance.
General guidelines recommend drinking at least 8 glasses of water per day, but individual needs may vary based on factors such as body weight, physical activity, and climate. Some people may need to drink more than 8 glasses per day to maintain adequate hydration while on a ketogenic diet. It is important to drink water regularly throughout the day and listen to your body to determine if you need to increase your fluid intake.
It is important to keep in mind that there are still many unanswered questions regarding the long-term effects of the ketogenic diet, especially after stopping it.
Further research is needed to explore the long-term effects of the ketogenic diet, including impacts on metabolic, cardiovascular, and neurological health, as well as its effectiveness in maintaining weight loss over time.
Only a better understanding of these aspects will allow us to provide more precise and safe guidelines for the adoption and maintenance of the ketogenic diet in the long term.
How to reintroduce carbs without gaining weight
When deciding to reintroduce carbohydrates after losing weight on a ketogenic diet, it is advisable to consult a dietitian for personalized advice.
However, there are some general recommendations to follow: After following a ketogenic diet, carbohydrate reintroduction should be gradual and well-planned to avoid sudden swings in blood sugar levels and other side effects.
Here are some tips for safely and effectively replenishing carbohydrates:
1. Start slowly : Add small amounts of complex carbohydrates to your diet, such as starchy vegetables (sweet potatoes, squash, carrots) and whole grains (brown rice, quinoa, farro). Start with one serving per day and carefully monitor your response.
2. Choose the right carbohydrates : It is essential to reintegrate carbohydrates carefully, favoring foods from non-genetically modified raw materials. Make a conscious choice, opting for pasta, bread and baked goods prepared with ancient varieties of durum wheat .
These foods tend to have a less drastic impact on blood sugar levels than refined foods, as refined and ultra-processed carbohydrates can cause unwanted blood sugar spikes. Choose foods rich in fiber, vitamins, and minerals to support your overall health and promote long-term well-being.
3. Monitor your body's response: Carefully observe how your body reacts to the introduction of carbohydrates. Pay attention to any symptoms of discomfort or changes in energy levels, your weight and especially your body fat and adjust the amount of carbohydrates you include accordingly.
Should You Take Supplements While on a Ketogenic Diet?
While on a Ketogenic Diet, it is essential to ensure an adequate intake of all necessary micronutrients.
In particular, it is advisable to increase the intake of alkalizing minerals such as potassium, magnesium, calcium, with enriched foods or supplements, such as our Day Up ! 👇
This helps balance out any high production of ketones, which can have an acidifying effect on the body. Making sure you get enough of these minerals is really important to maintaining balance and health while on the ketogenic diet.
Certain nutrients, which are readily available in grains like wheat, may have been restricted while on the ketogenic diet, causing side effects such as headaches, brain fog, fatigue, irritability, nausea, difficulty sleeping, and constipation, commonly known as the “ keto flu .”
What is the keto flu? The keto flu, also known as the "ketogenic flu," is a set of symptoms that some people may experience when starting a ketogenic diet, consisting of low blood sugar levels and the body's adaptation to producing ketones as its primary source of energy, with symptoms such as fatigue, tiredness, headaches, and decreased energy. These symptoms usually go away within a few days or weeks as the body adjusts to the new diet.
Ketone Levels Considered Safe
To maintain safe nutritional levels of ketosis, it is recommended to keep ketone levels in the range of 1.5-3.0 mmol/L, as recommended by researchers Stephen Phinney and Jeff Volek. These ketone levels can be monitored through urine and blood tests.
You can measure your urine ketone levels yourself using commercially available test kits. These kits contain test strips that react with the ketones in your urine.
However, it is important to note that measuring ketones in urine may not be highly accurate and may not necessarily reflect blood ketosis levels, which is considered a more accurate method.
What to eat if you are on the keto diet?
It’s really important to know what foods you’re going to eat before you start and how to incorporate more fat into your diet,” says Kristen Mancinelli, RD , author of The Ketogenic Diet: A Science-Proven Approach to Fast, Healthy Weight Loss , who is based in New York City.
Mancinelli shares his guide on choosing nutritious foods for keto here:
Proteins
Ketogenic diets are not high in protein (they focus on fat), so they should be consumed in moderation.
Freely
Grass-fed beef, fish, especially fatty fish like salmon, dark meat chicken
From time to time
Bacon, low-fat proteins like skinless chicken breast, and shrimp. These are great to include in your keto diet, but add a sauce on top for a little fat instead of eating them plain.
Never
While potentially high in fat, these protein sources can also be high in carbohydrates, and in the case of deli meats and chicken nuggets, these typically sodium-rich foods can raise blood pressure levels.
Cured meats with added sugar (read the label), meat marinated in sugary sauces, fish or chicken nuggets
Oil and Fats
Freely
Extra virgin olive oil , avocado, avocado oil
From time to time
Sunflower oil, safflower oil, corn oil, butter, whole milk, coconut oil
Never
Margarine, trans fats
Fruits and vegetables
Freely
Avocado, green leafy vegetables, such as spinach and arugula, celery, asparagus
From time to time
Leeks, spaghetti squash, eggplant, avocado, raspberries, lemon, tomatoes
Never
Potatoes, corn, raisins
Nuts and seeds
Freely
Walnuts, almonds, flax seeds, chia seeds
From time to time
Cashews and pistachios
Never
Nut butters, sweetened seeds, chocolate covered nuts
Dairy products
Freely
Feta, Parmesan
From time to time
Whole ricotta, whole greek yogurt, whole ricotta
Never
Milk, low-fat sweetened yogurt, ice cream
Sweeteners
Freely
Nobody
From time to time
Xylitol, Stevia, Erythritol, Artificial Sweeteners
Never
Agave, honey, maple syrup, white and brown sugars
Condiments and Sauces
Freely
Guacamole, mayonnaise (make sure no sugar is added)
From time to time
Raw garlic, tomato sauce (look for the one without added sugar), balsamic vinegar
Never
BBQ sauce, ketchup, honey mustard
Drinks
Freely
Water, unsweetened almond milk, bone broth, plain tea
From time to time
Black coffee, unsweetened carbonated water, zero-calorie drinks, alcohol
Never
Fruit juice, lemonade
Herbs and spices
Freely
Pepper, thyme, oregano and paprika
Occasionally
Ground ginger, garlic powder, onion powder
Never
No herbs or spices are off limits; they are generally fine to use in small amounts to add flavor to foods.
Ketogenic Diet for Vegetarians
Meat is a staple of the ketogenic diet, but that doesn’t mean the diet is off limits to vegetarians. As the high-fat, low-carb approach has grown in popularity, many vegetarians have jumped on the hype and found ways to make it work for them, too, by modifying the typical ketogenic diet menu and food list to fit their meatless lifestyle.
Here's what a typical day on the keto diet for vegetarians looks like:
- Breakfast with protein powder or protein pancakes made with eggs and protein powder
- Snack Sliced cucumber with sheep cheese or ricotta with sunflower seeds
- Lunch Large salad with avocado, greens, seeds and nuts or egg omelette with herb goat cheese and pesto
- Dinner Zucchini spaghetti (zoodles) with pesto and tofu; sautéed vegetables with tempeh; or spinach salad with cashew-crusted tofu, grilled zucchini, diced feta and high-polyphenolic extra virgin olive oil (Link our oil).
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GO TO THE NUTRITIONAL TESTFront Nutr. 2024; 11: 1322509. doi: 10.3389/fnut.2024.1322509 ; Ketogenic diet and behavior: insights from experimental studies
Cureus. 2023 Mar; 15(3): e36720. doi: 10.7759/cureus.36720 ; Metabolic Effects of Ketogenic Diets and Their Utilization in Obesity Management: A Systematic Review
J Nutr Metab. 2020; 2020: 3642035. doi: 10.1155/2020/3642035 ; Long-Term Ketogenic Diet Induces Metabolic Acidosis, Anemia, and Oxidative Stress in Healthy Wistar Rats
Nutrients. 2023 Dec; 15(23): 4998. doi: 10.3390/nu15234998 ; The Ketogenic Diet in the Prevention of Migraines in the Elderly
Review Atherosclerosis. 2020 Jan:292:119-126. doi: 10.1016/j.atherosclerosis.2019.11.021.; The ketogenic diet: Pros and cons
