I'm sure many of you have heard of the keto diet. Many celebrities are loyal to this type of eating, and it's gone viral on social media. It's so popular that artists like Bad Bunny are already mentioning it in their songs.
"Like the keto diet, I control myself and stay still."
But why is it so popular? Is its success justified?
The keto or ketogenic diet is an eating pattern that prioritizes fats as the basis of the diet at the expense of carbohydrates, so that our body enters a state of ketosis.
During ketosis, we obtain energy from ketone bodies derived from fats instead of carbohydrates, making it easier to reduce body fat since it's our primary fuel source. To enter ketosis, carbohydrates in our diet are reduced to less than 10%, compared to the usual 45-60%. Conversely, fats then make up at least 70% of our diet instead of the typical 30-35%.
This is a diet that excludes less desirable foods such as refined flours and processed pastries, but also healthy foods such as whole grains, tubers, legumes, and most fruits.
I believe that a healthy diet should not prohibit any food without a medical reason to do so, but it can be an interesting type of diet for certain pathologies, or to be used to improve insulin sensitivity and fat loss on a temporary basis.
So what are the benefits?
Studies on ketogenic diets tend to compare them with low-fat diets, obtaining the following results (1).
• Greater weight loss.
• Greater improvement in cholesterol and triglycerides
• Greater improvement in blood glucose.
• Better control of type 2 diabetes (as a result of the previous improvements).
It also appears to yield better results than a non-ketogenic low-carb diet. A recent Mayo Clinic study in the United States this year observed greater weight loss and better glycemic control in people with type 2 diabetes who followed a keto diet compared to a low-carb diet (2). However, more evidence is needed.
Furthermore, it has also shown to be interesting in neurodegenerative pathologies such as epilepsy (3) and it has recently been observed that it can improve cognitive function in Alzheimer's (4).
However, to obtain these benefits, you must:
1. To be and remain in ketosis for long periods
2. Follow a healthy ketogenic diet
Even without being in ketosis, a reduction in carbohydrates will result in weight loss. However, as we've seen, maintaining ketosis offers greater benefits for weight loss. To stay in ketosis, we typically shouldn't exceed 0.5g of net carbs per kg of body weight, which usually translates to a limit of between 20 and 40g of net carbs per day.
Heads up! We can also be in ketosis, but at the cost of eating less healthy foods. I've seen Instagram profiles bragging about being keto while having mascarpone cheese and bacon for breakfast. That's not the way to go.
If we want to benefit not only from body fat loss but also from improved cholesterol and blood sugar levels—otherwise, it could even worsen them—the ketogenic diet, like all diets, must be healthy. A healthy ketogenic diet should be based on plant-based foods such as leafy greens and berries, healthy fats like nuts, seeds, and avocados, and prioritize protein sources such as oily fish and shellfish.
However, while it's possible to maintain ketosis healthily, this is contraindicated in insulin-dependent diabetics, those with arrhythmias, serious kidney problems such as cirrhosis, and hyperuricemia. I also don't recommend it for type 2 diabetes patients taking metformin, as medication management is crucial and it can increase the risk of ketoacidosis.
In short, no, you don't need to resort to a keto diet to lose weight; the first step should always be healthy eating. But if you decide to follow a ketogenic diet, it should always be under the supervision of a professional to ensure it is healthy, safe, and effective.
I hope you enjoyed this article.
And don't be so afraid of fats!
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Coral Martín is a dietitian and psychologist. Every Tuesday she offers nutritional counseling at Salud Mediterránea Manuel Becerra: C/Ortega y Gasset 77.
Click here for more information and pricing for this service.
Bibliographic references
1. Choi, Y.J., Jeon, S.-M., & Shin, S. (2020). Impact of a Ketogenic Diet on Metabolic Parameters in Patients with Obesity or Overweight and with or without Type 2 Diabetes: A Meta-Analysis of Randomized Controlled Trials. Nutrients , 12 (7), E2005. https://doi.org/10.3390/nu12072005
2. Zaki, H.A., Iftikhar, H., Bashir, K., Gad, H., Samir Fahmy, A., & Elmoheen, A. (2022). A Comparative Study Evaluating the Effectiveness Between Ketogenic and Low-Carbohydrate Diets on Glycemic and Weight Control in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis. Cureus , 14 (5), e25528. https://doi.org/10.7759/cureus.25528
3. Martin, K., Jackson, CF, Levy, RG, & Cooper, P.N. (2016). Ketogenic diet and other dietary treatments for epilepsy. The Cochrane Database of Systematic Reviews , 2 , CD001903. https://doi.org/10.1002/14651858.CD001903.pub3
4. Phillips, MCL, Deprez, LM, Mortimer, GMN, Murtagh, DKJ, McCoy, S., Mylchreest, R., Gilbertson, LJ, Clark, KM, Simpson, PV, McManus, EJ, Oh, J.-E., Yadavaraj, S., King, VM, Pillai, A., Romero-Ferrando, B., Brinkhuis, M., Copeland, B.M., Samad, S., Liao, S., & Schepel, J.A.C. (2021). Randomized crossover trial of a modified ketogenic diet in Alzheimer's disease. Alzheimer's Research & Therapy , 13 (1), 51. https://doi.org/10.1186/s13195-021-00783-xTodo