Starting with the Cigarette Diet in 1925, the US has seen the number of prescribed diets grow into the hundreds with more coming out each year. Some of them are legitimate and based on sound research. Others, like the Baby Food Diet, Cotton Ball Diet, and Tapeworm Diet, are less so. Say what you will about fad diets, but there’s no shortage of creativity.
One diet that's become popular in recent years and has been grouped in with fad diets is the Ketogenic or Keto Diet. The diet has actually been around since the early 1900s when it was successfully used to treat epilepsy and brain cancer. (1) But you'd more likely recognize it from online pictures of people drinking butter coffee.
Eating keto means eating fat, lots of it. At least 70% of your calories should come from fat. For the rest, 25% should come from protein and 5% or less from carbs.
There are many diets in the US. Some are based in science, more are not. The keto diet is a diet that's based on eating at least 70% of calories from fat.
In most of the world, carbs are the body’s primary source of energy. To simplify some complex physiology, carbs are broken down into glucose. Glucose is then used to fuel your brain and muscles. Due to the global abundance of cheap carbs - primarily rice, wheat, and corn - this is how most of the world runs. However, there are a few cultures that don't have access to carbs and must use something else for fuel - fat.
When your body has no carbs, it naturally will turn to fat for energy. This causes your body to ramp up production of something called ketones and these ketones replace glucose as your body's fuel. When this happens, your body goes into ketosis. This is the goal of the keto diet.
Your body uses carbs to make glucose, which it runs on. With no carbs, your body can't use glucose for fuel. It uses ketones instead.
To get to ketosis, you need to eat a lot of fat. That doesn't mean you have a green light to eat bacon and donut sandwiches. There are good and bad fats and if you're going for ketosis, you want the good ones. That means nuts, seeds, fish, avocados, olive oil, eggs, poultry, coconuts, grass-fed meat, and full-fat dairy products. Common sense still applies, so industrial fats like margarine and all processed foods are a no go. Vegetables low in carbs like spinach, kale, bok choy, and cauliflower should be eaten in abundance.
Eat fats from quality, whole-food sources. Avoid processed fats. Eat leafy vegetables.
The difference between the keto diet and fad diets is that the keto diet is backed by a list of potential and proven benefits that are based on scientific research.
Research supports a number of benefits related to heart health, brain health, and weight loss.
Eating more calories than your body burns will make you gain weight. Eating more of your calories from fat will not. When carbs are restricted, eating more fat can actually increases fat loss. In one study, individuals lost an average 25 pounds over a 6-month period. (9) Physiologically, this makes sense. Because fat becomes your body’s main source of fuel, your body burns it at a much higher rate than it would normally. One study showed keto-adapted individuals burned 2.3x more fat than those on a Western diet. (10) That's more than twice as much fat.
Not only do you burn more fat, but you could also burn more of that elusive belly fat. There's evidence that ketogenic diets are unusually effective at shedding the gut. (11)
Excess calories cause weight gain. Eating more fat does not. Eating more fat can actually help you burn significantly more fat.
Research says otherwise. One study had elite gymnasts on a ketogenic diet for 30 days and compared their strength performance before and after. No significant difference was found between the athletes who were on a ketogenic diet versus those who weren't. (12) The only major difference between the two groups was that the keto group weighed an average 3.5 pounds less and carried 4.2 pounds less fat.
Two caveats should be mentioned about the above study. First, the sample size was quite small (only 8 participants). Second, the athletes also consumed a high amount of protein (up to 40% of calories) which would help retain muscle mass.
It is possible to follow a ketogenic diet without losing muscle if protein is kept at a moderate/high level.
Ketoacidosis - Some have warned that the keto diet is unsafe by arguing that it leads to ketoacidosis, a rise in blood acidity that could be fatal. However, unless you’re a diabetic, ketoacidosis is virtually impossible.
Keto Flu - One short term effect is often referred to as the "keto flu". This "flu" hits in the first few days as the body adapts to using fat for fuel. Symptoms include lack of energy, dizziness, mental fogginess and are usually gone by day three or four.
Long Term Effects - As of now, there don't appear to be any long term negative side effects. (13) The keyword is "now" because we (humans) also used to "know" that tobacco was so healthy that we called it "God's remedy". The point is that we don't know anything until science proves it beyond reasonable doubt and even then we still could be wrong.
As of now, the ketogenic diet doesn't have any long term negative effects.
The potential benefits are numerous - fat loss, mental clarity, longer life, and prevention of serious diseases like heart disease, diabetes, and even cancer. The risks are few, if any. Not many other diets can make this claim, so why aren't we call having butter coffee and bacon for breakfast?
Adherence. Limiting carbohydrates to less than 50g a day is not easy. Poultry, meat, and dairy have 0g carbs while leafy greens have very low amounts. But what many people don’t understand is that the keto diet is not just a diet, it’s a metabolic state. Too many carbs will knock you out of ketosis and if that happens you lose the benefits. That means no cheating. No chips on gameday and no drinks on Saturday night.
Adhering to a ketogenic diet is difficult. Deviating or "cheating" results in loss of all the benefits.
The keto diet is not another fad diet. Worst case, it's an effective fat loss tool with numerous medical applications. Best case, it could be one of the best diets for humans in terms of overall health and longevity. We can't conclusively say for sure and won't know until the whitecoats write up more studies. While we wait, try out some butter coffee (it's actually not bad) but whether it becomes a cornerstone of your diet is up to you.
1. Paoli, A., Rubini, A., Volek, J. S., & Grimaldi, K. A. (2014). Erratum: Beyond weight loss: A review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition,68(5), 641-641.
2. Westman, E. C., Yancy, W. S., Mavropoulos, J. C., Marquart, M., & Mcduffie, J. R. (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & Metabolism, 5(1), 36.
4. Skeaff, M., Mann, J., Morenga, L. T., & Mclean, R. (2015). Effects of Low-Carbohydrate and Low-Fat Diets. Annals of Internal Medicine, 162(5), 392.
5. Woolf, E. C., & Scheck, A. C. (2016). Ketogenic Diet as Adjunctive Therapy for Malignant Brain Cancer. Oxford Medicine Online.
6. Gasior, M., Rogawski, M. A., & Hartman, A. L. (2006). Neuroprotective and disease-modifying effects of the ketogenic diet. Behavioural Pharmacology, 17(5-6), 431-439.
7. Nankervis, S. A., Mitchell, J. M., Charchar, F. J., Mcglynn, M. A., & Lewandowski, P. A. (2013). Consumption of a low glycaemic index diet in late life extends lifespan of Balb/c mice with differential effects on DNA damage. Longevity & Healthspan, 2(1), 4.
8. Jonasson, L., Guldbrand, H., Lundberg, A. K., & Nystrom, F. H. (2014). Advice to follow a low-carbohydrate diet has a favourable impact on low-grade inflammation in type 2 diabetes compared with advice to follow a low-fat diet. Annals of Medicine, 46(3), 182-187.
9. Westman, E. C., Yancy, W. S., Mavropoulos, J. C., Marquart, M., & Mcduffie, J. R. (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & Metabolism, 5(1), 36.
10. Volek, J. S., Freidenreich, D. J., Saenz, C., Kunces, L. J., Creighton, B. C., Bartley, J. M., . . . Phinney, S. D. (2016). Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, 65(3), 100-110.
11. Meckling, K. A., O’Sullivan, C., & Saari, D. (2004). Comparison of a Low-Fat Diet to a Low-Carbohydrate Diet on Weight Loss, Body Composition, and Risk Factors for Diabetes and Cardiovascular Disease in Free-Living, Overweight Men and Women. The Journal of Clinical Endocrinology & Metabolism, 89(6), 2717-2723.
12. Paoli, A., Grimaldi, K., D’Agostino, D., Cenci, L., Moro, T., Bianco, A., & Palma, A. (2012). Ketogenic diet does not affect strength performance in elite artistic gymnasts. Journal of the International Society of Sports Nutrition, 9(1), 34.
13. Dashti, H. M., Mathew, T. C., Hussein, T., Asfar, S. K., Behbahani, A., Khoursheed, M. A., Al-Sayer, H. M., Bo-Abbas, Y. Y., … Al-Zaid, N. S. (2004). Long-term effects of a ketogenic diet in obese patients. Experimental and clinical cardiology, 9(3), 200-5.