Updated: Dec 10, 2019
Have you heard of the new magical diet that sheds pounds in a flash? ...
The ketogenic diet (KD) is the new trend. Everyone is talking about it. Everyone is trying it. It has been said that it is the diet that turns your body into a fat burning machine.. but is it true? Is there any evidence? Here is my two cents on the matter.
First off, let me explain this diet. KD is a very low carbohydrate (carbs), high fat and moderate protein diet that is not calorie-restricted (No need to starve yourself, WOOHOO!). Our body uses carbohydrates as it's primary source of energy, so the idea behind KD is that your body will be deprived of carbs and will be force to use fat for fuel. The fat is transformed in the liver into ketones that can be used by our brain and body for energy. This state is called ketosis. Our body naturally enter ketosis during a long fasting period or extended physical activity.
From a medical point of view, the KD diet is very interesting. There's a lot of evidence to show that KD is effective as a treatment for childhood drug-resistant epilepsy (1, 2) and it has been use since the 1920's. Studies are being done on KD as an adjuvant treatment for cancer, but there is still a lack of strong clinical evidence (3).
Now what about weight loss? While there are evidence that participants have lost weight and body fat on this diet (4,5) there are many limits and important aspects to consider.
Who are the participants? Most research on weight loss are conducted with obese or overweight participants inclusively (BMI >30). Thus the results may not apply for the general population since metabolic functions can be altered in obese/overweight individuals.
Most participants consume a standard All-American diet (SAD) prior to the studies. (check the diagram below). We all know that SAD is not optimal for health and can lead to weight gain. So comparing any diet meant for weight loss to SAD will most likely deliver results. Especially a diet as extreme as KD.
Studies use compare groups in order to show the impact of the intervention. Unfortunately, they compare participants who consume a KD vs. consume SAD. Therefore, comparing 2 extremes of the spectrum: a very unhealthy diet with a very restrictive diet. It is logical that there will be a difference between the groups.
(Diagram comparing SAD and KD. As you can tell, it is completely different. SAD is very unhealthy - Mostly processed food, oil, sweets and refined grains)
Studies have shown KD reduces appetite (6). Although participants have stated that they felt less hungry, studies have not been able to identify if this was due to ketosis or the increase content of fat and protein. Therefore without restricted carbs, we might be able to obtain de same appetite suppression effect.
A study showed that although there was a decrease in body fat percentage after following KD for 10 weeks, athletic performance was decreased due to low energy levels and difficulty to focus (7).
There are no studies on the potential long term effects of KD. Our bodies are built to use glucose as energy and not ketones (unless fasting). So we have no idea as of now what are the effects of the metabolic change.
Any diet can work. Temporarily. If you stick long enough to a low carb, high protein, plant based, paleo or soup diet, you CAN and WILL lose weight. The issue is that none of these diets are sustainable and honestly not fun at all. They are not lifestyle changes. Most studies evaluate the results after 6-10-52 weeks, but what after 2 years, 5 years & 10 years? Most people will gain back all the weight they lost in the following year, and may even gain more.
KD is an extreme diet and our body was not designed for anything extreme. In fact, we love balance, we are always trying to reach a state of homeostasis. Extreme dieting leads to cravings and inevitably over eating once you let yourself ''cheat''. And then the cycle begins.... You become more restrictive to make up for the cheat which leads to another binge. The psychological aspect of dieting is in full motion and you crave the food on your black list. It is STRESSFUL and you constantly think about food. This is not a healthy lifestyle.
In my opinion, the ketogenic diet is just another fad. Another ''simple'' solution to losing weight fast. There's is a lack of strong evidence to confirm that this is a good weight loss treatment and I would never suggest this to a friend! Healthy weight can be attained by living a balanced life. No diets. No restrictions. No stress!
I hoped this helps! If you have any questions or need help finding your healthy balance, contact me :)
Marie-Pier Pitre-D'Iorio, RD, B.Sc.Psychology
1.Daniel L. Keene, A Systematic Review of the Use of the Ketogenic Diet in Childhood Epilepsy, Pediatric Neurology, Volume 35, Issue 1, July 2006, Pages 1-5, ISSN 0887-8994, https://doi.org/10.1016/j.pediatrneurol.2006.01.005.
2.Elizabeth G Neal, Hannah Chaffe, Ruby H Schwartz, Margaret S Lawson, Nicole Edwards, Geogianna Fitzsimmons, Andrea Whitney, J Helen Cross, The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial, The Lancet Neurology, Volume 7, Issue 6, June 2008, Pages 500-506, ISSN 1474-4422, https://doi.org/10.1016/S1474-4422(08)70092-9.
3. Vergati, M., Krasniqi, E., Del Monte, G., Riondino, S., Vallone, D., Guadagni, F., … Roselli, M. (2017). Ketogenic diet and other dietary intervention strategies in the treatment of cancer. Current Medicinal Chemistry.
4.M.K. Gibas, K.J. Gibas, Induced and controlled dietary ketosis as a regulator of obesity and metabolic syndrome pathologies, Diab Met Syndr: Clin Res Rev (2017), http://dx.doi.org/10.1016/j.dsx.2017.03.022
5.Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. Am J Clin Nutr. 2006;83:260–74.
6. Gibson, A. A., Seimon, R. V., Lee, C. M. Y., Ayre, J., Franklin, J., Markovic, T. P., … Sainsbury, A. (2015). Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Obesity Reviews : An Official Journal of the International Association for the Study of Obesity, 16(1), 64–76. https://doi.org/10.1111/obr.12230
7. Urbain, P., Strom, L., Morawski, L., Wehrle, A., Deibert, P., & Bertz, H. (2017). Impact of a 6-week non-energy-restricted ketogenic diet on physical fitness, body composition and biochemical parameters in healthy adults. Nutrition & Metabolism, 14, 17. https://doi.org/10.1186/s12986-017-0175-5