Hello, welcome back to Adoración Linares' blog. In this article, we'll explore what keto diets are and what you should keep in mind if you're going to follow one.
What are keto diets?
Keto or ketogenic diets consist of a low-carbohydrate, high-fat eating plan that has been used for centuries to treat specific medical conditions. In the 19th century, the ketogenic diet was commonly used to help manage diabetes. In 1920, it was introduced as an effective treatment for epilepsy in children for whom medication was ineffective. The ketogenic diet has also been tested and used in closely controlled settings for cancer, diabetes, polycystic ovary syndrome, and Alzheimer's disease.
However, this diet is gaining considerable attention among people who want to lose weight due to the low-carb diet craze, which began in the 1970s with the Atkins diet (a very low-carbohydrate, high-protein diet that was a commercial success and popularized low-carbohydrate diets to a new level.) Currently, other low-carbohydrate diets, such as the Paleo, South Beach, and Dukan diets, are all high in protein but moderate in fat. In contrast, the ketogenic diet is distinguished by its exceptionally high fat content, typically between 701% and 801% of calories, while maintaining a moderate protein intake.
How they work
The premise of keto diets or ketogenic diets for weight loss is that if you deprive the body of glucose—the main source of energy for all the body's cells, which is obtained by... eat foods with carbohydrates– an alternative fuel called ketones is produced from stored fat (hence the term "ketogenic").
The brain is the organ in the body that demands the most glucose. It does so constantly and requires about 120 grams daily, since it cannot store glucose.
During fasting or when eating very few carbohydrates, the body first draws stored glucose from the liver and temporarily breaks down muscle to release glucose. If this continues for 3-4 days and stored glucose is completely depleted, blood levels of a hormone called insulin decrease, and the body begins to use fat as its primary fuel. The liver produces ketone bodies from fat, which can be used in the absence of glucose.
The accumulation of ketone bodies in the blood is called ketosis. Healthy people naturally experience mild ketosis during periods of fasting (for example, when sleeping overnight) and during intense exercise.
Proponents of the ketogenic diet claim that, if the diet is followed carefully, blood ketone levels should not reach a harmful level (known as "ketoacidosis"), as the brain will use ketones for fuel and healthy individuals usually produce enough insulin to prevent excess ketones from forming.
The speed at which ketosis occurs and the number of ketone bodies that accumulate in the blood varies from person to person and depends on factors such as body fat percentage and resting metabolic rate.
Keto diets
There is no single "standard" ketogenic diet with a specific ratio of macronutrients (carbohydrates, proteins, and fats). The ketogenic diet typically reduces total carbohydrate intake to less than 50 grams per day—less than the amount found in a medium-sized bagel—and can be as low as 20 grams per day.
Generally, the most well-known ketogenic resources suggest an average of 70-80% fat from total daily calories, 5-10% carbohydrates, and 10-20% protein. For a 2,000-calorie diet, this translates to approximately 165 grams of fat, 40 grams of carbohydrates, and 75 grams of protein.
The amount of protein recommended in the ketogenic diet is moderate compared to other low-carb, high-protein diets because eating too much protein can prevent ketosis. Protein amino acids can be converted into glucose, so a ketogenic diet allows for the consumption of enough protein to preserve lean body mass, including muscle, while still inducing ketosis.
There are many versions of ketogenic diets, but they all prohibit high-carbohydrate foods. Some of these foods may be obvious: refined and whole-grain starches such as bread, cereal, pasta, rice, and crackers; potatoes, corn, and other starchy vegetables; and fruit juices.
Some foods that may not be so obvious are legumes and most fruits. Most ketogenic plans allow foods high in saturated fats, such as fatty cuts of meat, processed meats, lard, and butter, as well as sources of unsaturated fats, such as nuts, seeds, avocados, vegetable oils, and oily fish. Depending on your source, ketogenic food lists can vary and even conflict.
The programs suggest following a ketogenic diet until the desired amount of weight is lost. Once this is achieved, to prevent weight regain, the diet can be followed for a few days a week or a few weeks a month, alternating with other days that allow for a higher carbohydrate intake.
The investigation so far
Keto diets have been shown to produce beneficial short-term metabolic changes. Along with weight loss, they have improved health parameters associated with excess weight, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides.
There is also growing interest in the use of low-carbohydrate diets, including the ketogenic diet, for type 2 diabetes. There are several theories as to why the ketogenic diet promotes weight loss, although these have not been consistently proven in research:
- A satiating effect with a decrease in food cravings due to the high fat content of the diet.
- A decrease in appetite-stimulating hormones, such as insulin and ghrelin, when restricted amounts of carbohydrates are eaten.
- A direct hunger-reducing function of ketone bodies, the body's main source of fuel in the diet.
- Increased calorie expenditure due to the metabolic effects of converting fats and proteins into glucose.
- Promoting fat loss versus lean body mass, partly due to decreased insulin levels.
Possible problems
Following a very high-fat diet can be difficult to maintain. The potential symptoms of extreme carbohydrate restriction, which can last from days to weeks, include hunger, fatigue, low mood, irritability, constipation, headaches, and brain fog. While these uncomfortable sensations may subside, staying satisfied with the limited variety of foods available and the restriction of otherwise enjoyable foods, such as a crisp apple or a creamy sweet potato, can present new challenges.
Some negative side effects of a long-term ketogenic diet have been suggested, such as an increased risk of kidney stones and osteoporosis, and elevated blood uric acid levels (a risk factor for gout). Potential nutrient deficiencies may arise if a variety of recommended foods are not included in the ketogenic diet.
It's important not to focus solely on consuming high-fat foods, but to include a daily variety of permitted meats, fish, vegetables, fruits, nuts, and seeds to ensure adequate intake of fiber, B vitamins, and minerals (iron, magnesium, zinc)—nutrients typically found in foods like whole grains, which are restricted in the diet. Since entire food groups are excluded, the assistance of a registered dietitian can be beneficial in creating a ketogenic diet that minimizes nutrient deficiencies.
Conclusion
The available research on the ketogenic diet for weight loss is still limited. Most studies conducted so far have had a small number of participants, have been short-term (12 weeks or less), and have not included control groups.
A ketogenic diet has been shown to provide short-term benefits for some people, including weight loss and improvements in total cholesterol, blood sugar, and blood pressure. However, these effects after one year, when compared to the effects of conventional weight-loss diets, are not significantly different.
Eliminating several food groups and the possibility of unpleasant symptoms can make adherence difficult. The emphasis on foods high in saturated fat also contradicts the recommendations of the Dietary Guidelines published by the Ministry of Health and can have adverse effects on LDL cholesterol in the blood. However, it is possible to modify the diet to emphasize foods low in saturated fat, such as olive oil, avocado, nuts, seeds, and fatty fish.
A ketogenic diet can be an option for some people who have struggled to lose weight with other methods. The exact ratio of fats, carbohydrates, and proteins needed to achieve health benefits will vary from person to person due to their genetic and body composition. Therefore, if you decide to start a ketogenic diet, it's recommended that you consult with your doctor and a registered dietitian to closely monitor any biochemical changes after beginning the regimen. It's also important that professionals create your meal plan to ensure it's tailored to your existing health conditions and to prevent nutritional deficiencies or other health complications. Your nutritionist can also guide you on reintroducing carbohydrates once you've lost weight.
A modified carbohydrate diet that follows the healthy eating plate model can produce adequate health and weight reduction benefits in the general population.
I hope this article on keto diets has been helpful. For more information, please feel free to contact me. Best regards, and see you soon on Adoración Linares' blog.
