Ketogenic Diet

Last Updated: November 18, 2022

Keto diets limit carb intake to under ≈50 grams a day and can reduce intake of easy-to-overeat, hyperpalatable foods. However, most trials don’t show a large weight-loss advantage over higher-carb diets, although individual results vary widely. Keto has therapeutic potential for a variety of health conditions.

Ketogenic Diet is most often used for

Summary

What is keto, and how is it different from "low carb"?

Keto is a fairly simple concept to understand:

Research studies generally peg under 50 grams as ketogenic, and 50-150 as "low-carbohydrate".[1][2] When most people eat less than around 50 grams a day of carbohydrate, they soon start producing high levels of something called "ketone bodies". These are simply breakdown products of fat, and are used to fuel cells that normally depend on glucose.

Why might keto help improve your health?

Keto's impact on health isn't so simple.

Your brain and nervous system usually run on glucose. Fueling it mostly with ketones is a whole new world to these cells, and may provide benefit. The main condition this has been studied for is epilepsy, but more research on other conditions is underway.

Keto's impact OUTSIDE of that, though, is more complicated. Keto is purported to aid with weight loss more so than other weight loss diets. The evidence for this is mixed, but tends to show fairly similar weight loss as other diets, according a meta-analysis of 32 trials comparing carb levels.[3] Keto benefits for a variety of conditions may stem from restriction of carbohydrate,[4] avoidance of typical carb-containing processed junk foods (so not the carb itself, but the food that contains it),[5][6] and/or benefits from the ketone bodies themselves.[7][8][9]

Is keto safe? Are there any detriments?

There are three different purported reasons that keto might not be totally safe:

First is the claim that high levels of ketones can be dangerous. This is generally not true with ketogenic diets, as ketoacidosis (dangerously high ketone levels typically caused by diabetes) doesn't seem to occur absent an uncontrolled medical condition, with no cases being reported in a two-year ketogenic diet study.[10] However, possibly the first case of ketoacidosis in a nondiabetic patient was reported in 2015, in a lactating woman on a ketogenic diet.[11]. A later case study purported to be the first of a healthy, nondiabetic, and non-lactating woman experiencing ketoacidosis.[12]

Ketone bodies are acidic by their very nature, although blood pH is typically well-regulated by our kidneys and lungs. While there may be a theoretical detriment to mild acidosis,[13] trials haven't shown adverse effects of sustained production of ketone bodies over time.

Second is the idea that going too long without getting "enough" carbohydrate is inherently dangerous. This is also generally not true, as carbohydrate isn't an essential nutrient (you can make all you need to survive, by a process called gluconeogenesis, without ingesting any through food or drink).[14] There isn't any trial evidence though on what the long term effects (e.g. 5-10 or more years) of carbohydrate deprivation are, and whether ketogenic diets have any negative impact on unstudied health conditions, certain genotypes, etc.

Finally, there are claims of harm from diets high in animal products, and most keto diets happen to be high in animal products. This claim is nearly impossible to evaluate with a simple yay or nay, given the huge number of studies involved with varying conclusions. What we know is that evidence is mixed, and slightly differs depending on the animal product in question (for example, fish consumption often shows a slight benefit for longevity in observational studies)[15][16]. Multi-decade randomized trials aren't feasible for foods, so we have to rely on imperfect evidence. In prospective (non-trial) studies, processed red meat often has a strong correlation with increased all-cause mortality and diseases, whereas unprocessed red meat often has a much smaller or no correlation.[17][18][19] Egg consumption typically shows negligible or no detriment to all-cause mortality and disease, [20][21] although again, evidence is mixed, with some other reviews finding a correlation of high egg intakes to disease.[22]

Meta-analytic results can differ depending on timeframe (intermediate versus longer term outcomes), which studies are excluded and included, and a variety of other factors. Some studies are funded by financially-interested parties (for example, the beef and egg industries), raising the possibility of publication bias or other biases. But other non-industry funded studies also tend to back up a detriment primarily from processed meats, and less or negligible detriment from unprocessed meats, depending on the amount eaten. This will remain an open question, given the difficulty in conducting long term randomized diet trials.

What else is Ketogenic Diet known as?
Note that Ketogenic Diet is also known as:
  • TKD
  • CKD
  • VLCKD
  • LCKD
  • keto
  • keto diet
  • keto diets
  • ketogenic diets
Ketogenic Diet should not be confused with:
  • Atkins
  • Low-carb
Dosage information

Consume under 50 grams of carbs a day, generally. Some people may need to lower this to under 20 grams, and some can produce more ketones even above 50 grams.

Examine Database: Ketogenic Diet
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References
  1. ^Gomez-Arbelaez D, Bellido D, Castro AI, Ordoñez-Mayan L, Carreira J, Galban C, Martinez-Olmos MA, Crujeiras AB, Sajoux I, Casanueva FFBody Composition Changes After Very-Low-Calorie Ketogenic Diet in Obesity Evaluated by 3 Standardized MethodsJ Clin Endocrinol Metab.(2017 Feb 1)
  2. ^Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GEEffects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitumAm J Clin Nutr.(2008 Jan)
  3. ^Hall KD, Guo JObesity Energetics: Body Weight Regulation and the Effects of Diet CompositionGastroenterology.(2017 May)
  4. ^Ludwig DS, Hu FB, Tappy L, Brand-Miller JDietary carbohydrates: role of quality and quantity in chronic diseaseBMJ.(2018 Jun 13)
  5. ^Hall KD, Ayuketah A, Brychta R, Cai H, Cassimatis T, Chen KY, Chung ST, Costa E, Courville A, Darcey V, Fletcher LA, Forde CG, Gharib AM, Guo J, Howard R, Joseph PV, McGehee S, Ouwerkerk R, Raisinger K, Rozga I, Stagliano M, Walter M, Walter PJ, Yang S, Zhou MUltra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food IntakeCell Metab.(2019 Jul 2)
  6. ^Fiolet T, Srour B, Sellem L, Kesse-Guyot E, Allès B, Méjean C, Deschasaux M, Fassier P, Latino-Martel P, Beslay M, Hercberg S, Lavalette C, Monteiro CA, Julia C, Touvier MConsumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohortBMJ.(2018 Feb 14)
  7. ^Puchalska P, Crawford PAMulti-dimensional Roles of Ketone Bodies in Fuel Metabolism, Signaling, and TherapeuticsCell Metab.(2017 Feb 7)
  8. ^Sedej SKetone bodies to the rescue for an aging heart?Cardiovasc Res.(2018 Jan 1)
  9. ^Wood TR, Stubbs BJ, Juul SEExogenous Ketone Bodies as Promising Neuroprotective Agents for Developmental Brain InjuryDev Neurosci.(2018)
  10. ^Qi Q, Durst R, Schwarzfuchs D, Leitersdorf E, Shpitzen S, Li Y, Wu H, Champagne CM, Hu FB, Stampfer MJ, Bray GA, Sacks FM, Shai I, Qi LCETP genotype and changes in lipid levels in response to weight-loss diet intervention in the POUNDS LOST and DIRECT randomized trialsJ Lipid Res.(2015 Mar)
  11. ^von Geijer L, Ekelund MKetoacidosis associated with low-carbohydrate diet in a non-diabetic lactating woman: a case reportJ Med Case Rep.(2015 Oct 1)
  12. ^Ullah W, Hamid M, Mohammad Ammar Abdullah H, Ur Rashid M, Inayat FAnother "D" in MUDPILES? A Review of Diet-Associated Nondiabetic KetoacidosisJ Investig Med High Impact Case Rep.(2018 Aug 23)
  13. ^Robey IFExamining the relationship between diet-induced acidosis and cancerNutr Metab (Lond).(2012 Aug 1)
  14. ^Westman ECIs dietary carbohydrate essential for human nutrition?Am J Clin Nutr.(2002 May)
  15. ^Jayedi A, Shab-Bidar S, Eimeri S, Djafarian KFish consumption and risk of all-cause and cardiovascular mortality: a dose-response meta-analysis of prospective observational studiesPublic Health Nutr.(2018 May)
  16. ^Sirot V, Leblanc JC, Margaritis IA risk-benefit analysis approach to seafood intake to determine optimal consumptionBr J Nutr.(2012 Jun)
  17. ^Larsson SC, Orsini NRed meat and processed meat consumption and all-cause mortality: a meta-analysisAm J Epidemiol.(2014 Feb 1)
  18. ^Farvid MS, Stern MC, Norat T, Sasazuki S, Vineis P, Weijenberg MP, Wolk A, Wu K, Stewart BW, Cho EConsumption of red and processed meat and breast cancer incidence: A systematic review and meta-analysis of prospective studiesInt J Cancer.(2018 Dec 1)
  19. ^O'Connor LE, Kim JE, Campbell WWTotal red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trialsAm J Clin Nutr.(2017 Jan)
  20. ^Mazidi M, Katsiki N, Mikhailidis DP, Pencina MJ, Banach MEgg Consumption and Risk of Total and Cause-Specific Mortality: An Individual-Based Cohort Study and Pooling Prospective Studies on Behalf of the Lipid and Blood Pressure Meta-analysis Collaboration (LBPMC) GroupJ Am Coll Nutr.(2019 Aug)
  21. ^Shin JY, Xun P, Nakamura Y, He KEgg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysisAm J Clin Nutr.(2013 Jul)
  22. ^Khawaja O, Singh H, Luni F, Kabour A, Ali SS, Taleb M, Ahmed H, Gaziano JM, Djoussé LEgg Consumption and Incidence of Heart Failure: A Meta-Analysis of Prospective Cohort StudiesFront Nutr.(2017 Mar 27)
Examine Database References
  1. Hydration (Total Body Water) - Boden G, Sargrad K, Homko C, Mozzoli M, Stein TPEffect of a low-carbohydrate diet on appetite, blood glucose levels, and insulin resistance in obese patients with type 2 diabetesAnn Intern Med.(2005 Mar 15)
  2. Low-density lipoprotein (LDL) - Athinarayanan SJ, Adams RN, Hallberg SJ, McKenzie AL, Bhanpuri NH, Campbell WW, Volek JS, Phinney SD, McCarter JPLong-Term Effects of a Novel Continuous Remote Care Intervention Including Nutritional Ketosis for the Management of Type 2 Diabetes: A 2-Year Non-randomized Clinical TrialFront Endocrinol (Lausanne).(2019 Jun 5)
  3. Blood Flow - Francois ME, Myette-Cote E, Bammert TD, Durrer C, Neudorf H, DeSouza CA, Little JPCarbohydrate restriction with postmeal walking effectively mitigates postprandial hyperglycemia and improves endothelial function in type 2 diabetesAm J Physiol Heart Circ Physiol.(2018 Jan 1)
  4. Triglycerides - Myette-Côté É, Durrer C, Neudorf H, Bammert TD, Botezelli JD, Johnson JD, DeSouza CA, Little JPThe effect of a short-term low-carbohydrate, high-fat diet with or without postmeal walks on glycemic control and inflammation in type 2 diabetes: a randomized trialAm J Physiol Regul Integr Comp Physiol.(2018 Dec 1)
  5. Low-density lipoprotein (LDL) - Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DAA randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy womenJ Clin Endocrinol Metab.(2003 Apr)
  6. Low-density lipoprotein (LDL) - Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears BKetogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate dietsAm J Clin Nutr.(2006 May)
  7. Low-density lipoprotein (LDL) - Urbain P, Strom L, Morawski L, Wehrle A, Deibert P, Bertz HImpact of a 6-week non-energy-restricted ketogenic diet on physical fitness, body composition and biochemical parameters in healthy adultsNutr Metab (Lond).(2017 Feb 20)
  8. Low-density lipoprotein (LDL) - Noakes M, Foster PR, Keogh JB, James AP, Mamo JC, Clifton PMComparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular riskNutr Metab (Lond).(2006 Jan 11)
  9. Low-density lipoprotein (LDL) - Partsalaki I, Karvela A, Spiliotis BEMetabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescentsJ Pediatr Endocrinol Metab.(2012)
  10. Low-density lipoprotein (LDL) - Yancy WS Jr, Westman EC, McDuffie JR, Grambow SC, Jeffreys AS, Bolton J, Chalecki A, Oddone EZA randomized trial of a low-carbohydrate diet vs orlistat plus a low-fat diet for weight lossArch Intern Med.(2010 Jan 25)
  11. Low-density lipoprotein (LDL) - Hernandez TL, Sutherland JP, Wolfe P, Allian-Sauer M, Capell WH, Talley ND, Wyatt HR, Foster GD, Hill JO, Eckel RHLack of suppression of circulating free fatty acids and hypercholesterolemia during weight loss on a high-fat, low-carbohydrate dietAm J Clin Nutr.(2010 Mar)
  12. Weight - Vazquez JA, Kazi ULipolysis and gluconeogenesis from glycerol during weight reduction with very-low-calorie dietsMetabolism.(1994 Oct)
  13. Weight - Parker N Hyde, Teryn N Sapper, Christopher D Crabtree, Richard A LaFountain, Madison L Bowling, Alex Buga, Brandon Fell, Fionn T McSwiney, Ryan M Dickerson, Vincent J Miller, Debbie Scandling, Orlando P Simonetti, Stephen D Phinney, William J Kraemer, Sarah A King, Ronald M Krauss, Jeff S VolekDietary carbohydrate restriction improves metabolic syndrome independent of weight lossJCI Insight.(2019 Jun 20)
  14. Lean Mass - Phillips SA, Jurva JW, Syed AQ, Syed AQ, Kulinski JP, Pleuss J, Hoffmann RG, Gutterman DDBenefit of low-fat over low-carbohydrate diet on endothelial health in obesityHypertension.(2008 Feb)
  15. Lean Mass - Varady KA, Bhutani S, Klempel MC, Phillips SAImprovements in vascular health by a low-fat diet, but not a high-fat diet, are mediated by changes in adipocyte biologyNutr J.(2011 Jan 20)
  16. Low-density lipoprotein (LDL) - Foster GD, Wyatt HR, Hill JO, McGuckin BG, Brill C, Mohammed BS, Szapary PO, Rader DJ, Edman JS, Klein SA randomized trial of a low-carbohydrate diet for obesityN Engl J Med.(2003 May 22)
  17. Low-density lipoprotein (LDL) - Keogh JB, Brinkworth GD, Noakes M, Belobrajdic DP, Buckley JD, Clifton PMEffects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesityAm J Clin Nutr.(2008 Mar)
  18. Low-density lipoprotein (LDL) - Volek JS, Sharman MJ, Gómez AL, DiPasquale C, Roti M, Pumerantz A, Kraemer WJComparison of a very low-carbohydrate and low-fat diet on fasting lipids, LDL subclasses, insulin resistance, and postprandial lipemic responses in overweight womenJ Am Coll Nutr.(2004 Apr)
  19. Triglycerides - Rosenbaum M, Hall KD, Guo J, Ravussin E, Mayer LS, Reitman ML, Smith SR, Walsh BT, Leibel RLGlucose and Lipid Homeostasis and Inflammation in Humans Following an Isocaloric Ketogenic DietObesity (Silver Spring).(2019 Jun)
  20. Total cholesterol - Sharman MJ, Gómez AL, Kraemer WJ, Volek JSVery low-carbohydrate and low-fat diets affect fasting lipids and postprandial lipemia differently in overweight menJ Nutr.(2004 Apr)
  21. Noradrenaline - Bisschop PH, Pereira Arias AM, Ackermans MT, Endert E, Pijl H, Kuipers F, Meijer AJ, Sauerwein HP, Romijn JAThe effects of carbohydrate variation in isocaloric diets on glycogenolysis and gluconeogenesis in healthy menJ Clin Endocrinol Metab.(2000 May)
  22. Blood glucose - Kirk E, Reeds DN, Finck BN, Mayurranjan SM, Patterson BW, Klein SDietary fat and carbohydrates differentially alter insulin sensitivity during caloric restrictionGastroenterology.(2009 May)
  23. Triglycerides - Ranjan A, Schmidt S, Damm-Frydenberg C, Holst JJ, Madsbad S, Nørgaard KShort-term effects of a low carbohydrate diet on glycaemic variables and cardiovascular risk markers in patients with type 1 diabetes: A randomized open-label crossover trialDiabetes Obes Metab.(2017 Oct)
  24. Low-density lipoprotein (LDL) - Phillips MCL, Murtagh DKJ, Gilbertson LJ, Asztely FJS, Lynch CDPLow-fat versus ketogenic diet in Parkinson's disease: A pilot randomized controlled trialMov Disord.(2018 Aug)
  25. Body Fat - Cohen CW, Fontaine KR, Arend RC, Alvarez RD, Leath CA III, Huh WK, Bevis KS, Kim KH, Straughn JM Jr, Gower BAA Ketogenic Diet Reduces Central Obesity and Serum Insulin in Women with Ovarian or Endometrial CancerJ Nutr.(2018 Aug 1)