The ketogenic diet, aka the the keto diet. A therapeutic diet turned fad diet.
As a registered dietitian witnessing the misuse of the ketogenic diet, I have to admit I really hoped that it was a passing fad.
This fat dominant diet really took off in the early 2000’s, and I gather, in part to social media’s role and the ever growing “it worked for them so it must work for me” syndrome. But the question remains, is a keto diet healthy?
History of the ketogenic diet
The ketogenic diet first came into use in the 1920’s as a therapeutic diet. What does that mean? A therapeutic diet is a diet utilized to treat a medical condition. In the 1920’s, that condition was epilepsy. It has evolved to be used in obesity medicine and has been studied for efficacy in diabetes, polycystic ovarian syndrome and cancer among others.1
You may also recognize the ketogenic diet masquerading under another popular diet name, the Atkin’s Diet. Note two distinct differences in the uses of the ketogenic diet- one as ‘food as medicine’ as a therapy and the other as a weight loss or fad diet that promises quick weight loss while eliminating entire food groups in the process. More on that later.
What is the ketogenic diet?
A keto diet is an extremely high fat, very low carb diet with 70% of calories coming from fat, 5-10% from carbohydrate and the remaining 20-25% from protein. On a ketogenic diet the maximum amount of carbohydrate per day hovers around 50 grams, with some going as low as 20 grams. To put that into perspective, there are about 50 grams of carbs in one cup of cooked rice and about 27 grams in a medium banana.
The premise of keto is that the body goes from burning carbohydrate, and thus glucose, for fuel to burning fat and using the by-product, ketones, for fuel. When the body converts from glucose to ketones then the body is in a state of ketosis.
Is a keto diet healthy?
Here are some of things to think about if you are considering a ketogenic diet:
1) Any time you severely restrict one food group, in this case carbohydrates, you deprive your body of all of the nutrients associated with that group. The keto diet eliminates whole grains, fruit, starchy vegetables and legumes. Can you imagine the deficit not only in fiber, but also in vitamins, minerals, antioxidants and phytochemicals that only come from certain fruits, grains, beans and legumes. No grapes you say…well there goes an excellent source of resveratrol…a powerful antioxidant that is cardioprotective, fights free radicals that cause aging and disease such as cancer, has anti-tumor activity, is neuroprotective and anti-inflammatory.
This is just one example of a food on the keto restricted list…just think of all of the other nutrients lost or diminished by going keto. (Side note: think you can make up for all of those missing nutrients by taking supplements? Think again. Vitamins and minerals are not absorbed the same ways as their counterparts from whole plant foods…but that’s another post for another day.) In conclusion, undernutrition may be a problem in the long run.
To recap and hit home on this point…the ketogenic diet allows foods such as bacon, butter, sour cream, cream cheese, cheddar, eggs and pork, but restricts nutrient dense lentils, potatoes, sweet potatoes, winter squash, beets, grapes, bananas, oranges and oatmeal. To be fair I should mention that the keto diet does allow plant foods such as avocado, greens, cauliflower, broccoli, berries and emphasizes whole foods.
2) Remember that grape from example one that is cardioprotective? On the flipside, consuming a diet that is high fat is exactly the opposite of cardioprotective. Remember when consuming too much butter, a saturated fat, was cause for alarm as it can cause plaque buildup in the arteries and lead to hardening and eventual heart disease? Nothing has changed folks.
Putting butter in coffee and drinking it in the name of a “diet” does not change what it does in your body. It is well known and well documented that following a high fat, predominantly animal based diet causes increased total cholesterol and LDL cholesterol and risk for cardiovascular disease.2
3) The next downfall of the ketogenic diet is probably the biggest heavy hitter for me and that is it causes INSULIN RESISTANCE. What is insulin resistance? It is the inability of the cells to respond to insulin and thus do their job of removing glucose from the bloodstream. The result…high circulating levels of glucose in the blood, i.e. high blood sugar.
Why is this such a big deal?
Insulin resistance is one of the hallmarks of metabolic syndrome. Metabolic syndrome is a collection of conditions (high blood pressure, insulin resistance, obesity, dyslipidemia) that increase the risk of developing type II diabetes and cardiovascular disease.
But wait, you’ve heard that the ketogenic diet is beneficial for type II diabetics so how is it that the very same diet can cause the disease?
It would appear that initially the ketogenic diet achieves excellent glucose control. But how would one get a poor glucose reading if the source, carbohydrate, comprises a mere 5-10% of total intake. It would follow that blood glucose readings would seem improved. Over time, however, something happens after following a high fat diet. An accumulation of fat or lipid in the cells occurs. This buildup is termed intramyocellular fat, which also occurs in the liver and is termed intrahepatic lipids. This microscopic fat build up blocks the mechanism for glucose uptake in cells, i.e. insulin resistance.3
In stark contrast, high carbohydrate, high plant fiber diets show promise for nutrition therapy in ameliorating or reversing type II diabetes. In one study, such a diet resulted in decrease or complete discontinuation of insulin therapy in type II diabetic patients.4
4) Another pitfall of the ketogenic diet is lack of fiber (unless the diet is carefully planned which takes work! Preferably with a registered dietitian). Eliminating fruit, grains, starchy vegetables and legumes is essentially omitting major dietary sources of fiber. The dangers of a low fiber diet include constipation, risk for intestinal disorders such as inflammatory bowel disease, damage to the gut microbiome and thus the immune system (which adds on another host of issues). A high fiber diet on the other hand, one that is plant based, is protective against heart disease, type II diabetes, diverticulitis and colon cancer.5
A study in the Lancet reports clinical trials showing that intake of high dietary fiber significantly lowers bodyweight, systolic blood pressure, and total cholesterol when compared with lower intakes of dietary fiber.6 A whole food plant based diet is one that easily reaches the recommended MINIMUM of 25-30 grams per day.
5) The question remains, is the adoption of a ketogenic diet sustainable? There are two perspectives from which to view sustainability- one a planetary perspective and a palate/health perspective. First off, the ketogenic diet is highly animal based. Emissions from livestock farming alone are detrimental to our environment when you consider deforestation for livestock raising, feed production and enteric emissions (manure) from the animals themselves.7
Secondly, how sustainable is a long-term adoption of the ketogenic diet? Living without fruits, legumes, and grains may prove difficult for some in the long run. Furthermore, long term effects of a low carb, high fat diet are not fully understood or documented.
BOTTOM LINE: The longest living and thriving populations in the world, also known as the Blue Zones, consume a low fat, high fiber plant based diet. The ketogenic diet on the other hand offers short-term gain, for highly likely long-term pain.
References:
- Paoli, A., Rubini, A., Volek, J. S., & Grimaldi, K. A. (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European journal of clinical nutrition, 67(8), 789–796. https://doi.org/10.1038/ejcn.2013.116
- Nordmann AJ, Nordmann A, Briel M, Keller U, Yancy WS Jr, Brehm BJ, Bucher HC. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006 Feb 13;166(3):285-93. doi: 10.1001/archinte.166.3.285. Erratum in: Arch Intern Med. 2006 Apr 24;166(8):932. PMID: 16476868.
- Bachmann OP, Dahl DB, Brechtel K, Machann J, Haap M, Maier T, Loviscach M, Stumvoll M, Claussen CD, Schick F, Häring HU, Jacob S. Effects of intravenous and dietary lipid challenge on intramyocellular lipid content and the relation with insulin sensitivity in humans. Diabetes. 2001 Nov;50(11):2579-84. doi: 10.2337/diabetes.50.11.2579. PMID: 11679437.
- Anderson JW, Ward K. High-carbohydrate, high-fiber diets for insulin-treated men with diabetes mellitus. Am J Clin Nutr. 1979 Nov;32(11):2312-21. doi: 10.1093/ajcn/32.11.2312. PMID: 495550.
- Dahl, WJ, Stewart, ML. Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber. J of the Academy of Nutrition and Dietetics. 2015 Nov; 115(11):1861-1870. doi: https://doi.org/10.1016/j.jand.2015.09.003
- Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019 Feb 2;393(10170):434-445. doi: 10.1016/S0140-6736(18)31809-9. Epub 2019 Jan 10. Erratum in: Lancet. 2019 Feb 2;393(10170):406. PMID: 30638909.
- Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Science. 2018 Jun 1;360(6392):987-992. doi: 10.1126/science.aaq0216. Erratum in: Science. 2019 Feb 22;363(6429): PMID: 29853680.