The Ketogenic diet has been all the rage lately with its claims of weight loss glory and sciency sounding words used to describe it. However, like all extreme diets, there are reasons both to jeer and cheer. So today, I wanted to give a short and sweet summary of what Keto is, what actually happens, and who all should consider using it.
What Is Keto?
In short, if you don’t eat carbs, your body will turn fat into ketone bodies that act like sugar in the tissues that need them. More specifically, the ketogenic diet involves severely restricting carbohydrate intake to about 10-20 grams per day while having a high fat intake, along with moderate protein consumption. So when people hear that the Keto diet forces your body to burn fat, they think “Eureka! It’s the holy grail of weight loss!!!!” In the short term, you will lose a lot of weight, which will get you motivated to stick with the diet. But this is water weight that will return once you eat carbs again and restore the glycogen (muscle fuel) to your muscles. However, what we do know is that ketogenic diets don’t seem to provide a metabolic advantage or result in a higher rate of fat loss when compared to isocaloric non-ketogenic diets with equal amounts of protein (1). Just because you burn fat doesn’t mean you lose fat!
Those who swear by Keto also say that fat is good for you, sugar is bad,the diet can reduce inflammation, high fat diets make you burn more calories, carbohydrates are stored more easily than fat, eating fat before a meal makes you eat less, you eat less when you eat high-fat meals, and fat is more satiating than carbohydrates. Almost sounds like this diet is too good to be true! Well… it is.
No, sugar is not by itself bad for you when used in moderation. The old notion that specific foods will raise and lower your insulin (glycemic index) has been called into question, and can in large part be dismissed because we all react differently even when given the same foods (2).
High-fat diets won’t make you burn more calories (4).
Sugar isn’t stored more easily as fat when compared to other calorie sources (5), and the adverse effects of a high-glycemic diet are likely due to increased energy consumption rather than to increased fat storage (6).
Consuming fat before a meal won’t make you eat any less, however, consuming carbs or protein will (7).
Eating meals that are energy dense is a bad idea whether it’s fat or sugar that we are talking about (8).
Fat is the LEAST satiating (filling) macronutrient (9).
How It Can Work For You
Keto isn’t all nonsense and fairy tails. It can, and will, actually work for many people who use it. However, it works because it restricts a number of calories your taking in which can be done just as easily by reducing calories from your fat intake (10). In the long term, going the Keto route seems to work great because it in part forces you to avoid calorie dense foods (11). And while similar high-fat diet fads such as Paleo/bullet proof are bad for your blood lipid/cholesterol levels (12), Keto does not encourage consumption of large amounts of saturated fat (13). In fact, Keto seems to increase the amount of HDL (good cholesterol) and other hormones (14).
Much of the Ketogenic diet mythology revolves around false claims and over exaggeration of the truth. However, it works. As long as you can handle the restrictions, Keto works the same as every other successful diet. You burn more calories than you consume. It’s also safe and comes with other health benefits like a better blood lipid profile. So if it sounds doable for you, give it a shot and let me know how it works for you!
1. Hall, K. D., Chen, K. Y., Guo, J., Lam, Y. Y., Leibel, R. L., Mayer, L. E., … & Ravussin, E. (2016). Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. The American journal of clinical nutrition, 104(2), 324-333.
2. Zeevi, D., Korem, T., Zmora, N., Israeli, D., Rothschild, D., Weinberger, A., … & Suez, J. (2015). Personalized nutrition by prediction of glycemic responses. Cell, 163(5), 1079-1094.
3. Dror, E., Dalmas, E., Meier, D. T., Wueest, S., Thévenet, J., Thienel, C., … & Vallois, D. (2017). Postprandial macrophage-derived IL-1 [beta] stimulates insulin, and both synergistically promote glucose disposal and inflammation. Nature immunology.
4. Thomas, C. D., Peters, J. C., Reed, G. W., Abumrad, N. N., Sun, M. I. N. G., & Hill, J. O. (1992). Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans. The American journal of clinical nutrition, 55(5), 934-942.
5. Veum, V. L., Laupsa-Borge, J., Eng, Ø., Rostrup, E., Larsen, T. H., Nordrehaug, J. E., … & Mellgren, G. (2017). Visceral adiposity and metabolic syndrome after very high–fat and low-fat isocaloric diets: a randomized controlled trial. The American Journal of Clinical Nutrition, 105(1), 85-99.
6. Bosy-Westphal, A., Hägele, F., & Nas, A. (2016). Impact of dietary glycemic challenge on fuel partitioning. European journal of clinical nutrition.
7. Stubbs, R. J., Harbron, C. G., Murgatroyd, P. R., & Prentice, A. M. (1995). Covert manipulation of dietary fat and energy density: effect on substrate flux and food intake in men eating ad libitum. The American journal of clinical nutrition, 62(2), 316-329.
8. Rolls, B. J. (2000). The role of energy density in the overconsumption of fat. The Journal of nutrition, 130(2), 268S-271S.
9. Weight, L. (1995). A satiety index of common foods. European journal of clinical nutrition, 49(9), 675-690.
10. Sacks, F. M., Bray, G. A., Carey, V. J., Smith, S. R., Ryan, D. H., Anton, S. D., … & Leboff, M. S. (2009). Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med, 2009(360), 859-873.
11. Bueno, N. B., de Melo, I. S. V., de Oliveira, S. L., & da Rocha Ataide, T. (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 110(07), 1178-1187.
12. Smith, M., Trexler, E., Sommer, A., Starkoff, B., & Devor, S. (2014). Unrestricted Paleolithic diet is associated with unfavorable changes to blood lipids in healthy subjects. International Journal of Exercise Science, 7(2), 4.
13. Zong, G., Li, Y., Wanders, A. J., Alssema, M., Zock, P. L., Willett, W. C., … & Sun, Q. (2016). Intake of individual saturated fatty acids and risk of coronary heart disease in US men and women: two prospective longitudinal cohort studies. bmj, 355, i5796.
14. Silva, J. (2014). The effects of very high fat, very low carbohydrate diets on safety, blood lipid profile, and anabolic hormone status. Journal of the International Society of Sports Nutrition, 11(1), P39.