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.

Don't miss out on the latest research


Background Information



Humans have always used ketone bodies for fuel. Even if you've never "gone keto", you too have used ketone bodies. That's because they're present in low levels after a period of even short fasting, such as nightly sleep. After a typical period of sleep, ketone bodies supply 2–6% of your energy requirements, which bumps up to 30-40% after three days without any food.[23]

The official history of the ketogenic diets started in the 1920s as an epilepsy treatment, although ketone bodies themselves were first discovered in the mid 1800s, in the urine of patients with diabetes.[24] From the mid 1900s onwards, ketogenic diets were used less and less, as medications were used for epilepsy control.[25] They came back onto the scene in the early 2000s, in the form of a "modified Atkins" diet used for intractable seizures.[26]

In modern research studies, you may see keto interchangeably referred to as "ketogenic diet", "low-carb ketogenic diet" (LCKD),[27] or "very low-carb ketogenic diet" (VLCKD).[28] Occasionally, you may run into "targeted ketogenic diet" (TKD, where carb intake is concentrated into the hours around exercise) or "cyclical ketogenic diet" (CKD, where a few days of keto is followed by a day or two of higher carb intake). These are more typically referred to in online discussion of bodybuilding diets,[29] and the occasional animal study.[30]



There are five major ways that ketones can become elevated.

First, and most simply, fasting will lead to increased ketone production as your body's glycogen stores are depleted.[31]

Second, prolonged exercise results in increased ketone production, especially if you're already eating a low-carb diet.[32]

Third, diabetes can result in elevated levels of ketones, not only in insulin-dependent type 1 and type 2 diabetics, but also in non-insulin dependent type 2 diabetics.[33][34] Even if those who aren't yet diabetic, elevated levels of ketones can predict worse blood sugar control and development of diabetes in the following years.[35]

Fourth, supplementing with ketones themselves (i.e. exogenous ketones) or consuming large amounts of coconut fat (which contains medium chain triglyerides that can be broken down into ketones), will raise ketone levels even when not eating low-carb.[36][37]

Fifth, typical ketogenic diets will cause sustained ketone production due to low carb intake. Typical ketogenic diets can be supplemented with exogenous ketones as well, if higher ketone levels are desired, and MCT ketogenic diets with higher carb intake have been commonly used for epilepsy.[38]

Some food groups are not feasible to include in a ketogenic diet on a regular basis due to carb content, such as grains. Other groups can be eaten ad libitum, such as animal products (other than honey). Many types of foods fall in a middle ground though, such as fruits and dairy. Too much of high-carb varieties can cause you to eclipse your carb limit and be kicked out of ketosis.


Dietary adherence

Keto is only effective if you maintain it; occasional keto is fine but yo-yo dieting with keto followed by carb binges is not.

Keto dieters tend to eat less than higher carb dieters when given free reign to choose their food.[39] This is a boon for adherence. When looking at all trials measuring adherence, keto had a similar adherence rate as other diets, at around 24%.[40] That being said, carb intake, on average, creeps up over time in longer-term studies, with longer term studies having similar adherence as longer term non-keto studies.[41][42] This masks individual differences though - some stick to it strictly, others go way off track.

In a two-year open-label (non-randomized) study, dropout rates were 35% for the keto group and 28% for the control group.[43]




Side Effects and Adverse Events

The most reliable data for side effects and adverse events come from large trials in children with epilepsy. These show varying rates of a variety of possible side effects, from infrequent gallstones and elevated liver enzymes to more frequent elevated lipids and gastrointestinal upset.[44] Some side effects such as nausea and vomiting may be more likely in the first weeks of the diet, as you adapt to higher ketone levels.[45] Also, acetone can be exhaled and is a fairly accurate marker of ketosis,[46] but can unfortunately also be perceived as "bad breath" by some.

Certain electrolytes (specifically calcium, magnesium, sodium, and potassium) can be low on keto diets.[47][48][49][50] If you're low on any of these, supplementation or changing your food choices to more nutrient-dense foods can reduce side effects.

There are several health conditions for which keto is absolutely contraindicated, such as Porphyria and genetic deficiencies like fatty acid beta-oxidation defects.[51] Other contexts haven't had much if any keto research, and caution is warranted, such as with pregnancy and eating disorders.

For those undergoing a keto diet for serious medical conditions such as epilepsy, accidentally ingesting too much carbohydrate via medication or supplement can disrupt ketosis and indirectly cause danger through reduced diet efficacy. Chewable and liquid medication may have relatively high carb levels, not all of which are accurately labeled.[52][53][54]


Theoretical safety considerations

Several objections have been raised to low-carb diets including keto, positing theories of harm but not yet showing it through trial evidence.

One such objection is that a lack of carbohydrate could be detrimental to gut and immune health.[55] This doesn't appear to be born out in trials, which rather often show either a neutral or beneficial effect for gut health.[56] However, there is much uncertainty here. Researchers have found that ketogenic diets in children with epilepsy reduces levels of certain beneficial bacteria. Whether this has any health implications, though, is uncertain.[57]

Because keto has also been proposed as a general strategy for weight loss and diabetes prevention, some researchers have recommended a more moderate low-carb diet (100-150 grams of carbs) given the relative lack of long-term safety data for ketogenic diets.[58]

There is a perception that micronutrient intake will be low on ketogenic diets. That is not necessarily the case, as keto diets that are well-formulated (similar to the case for any other diet) can meet all micronutrient requirements.[59] A ketogenic diet that's consistently high in red meat, though, could theoretically contribute to iron overload in those who are genetically susceptible. Too much iron is implicated in Alzheimer’s, heart disease, and colorectal cancer.[60][61][62] Nearly one million Americans who have genetic susceptibility due to having hereditary hemochromatosis, a condition where you absorb too much dietary iron.[63]


Effects on Food Intake



In most studies, keto diets decrease hunger and desire to eat.[42] The most important factor in this may be swapping refined carbohydrate for protein, as protein is the most satiating macronutrient.[64] Ketone bodies themselves may also reduce appetite, although this is still an open research question.[65][43]


Effects on Body Composition


Fat Mass

There are two types of studies looking at fat mass: free-living studies (where you assign one group a keto diet and another non-keto, and track their fat loss over time) and metabolic ward studies (where you consign participants in each group to a metabolic ward, to tightly control their diet). The former can be much longer than the latter, but lack of dietary control can make results less reliable. Free-living studies do, however, reflect real-world adherence and regular life better.

Metabolic ward studies show similar fat loss in keto dieters as non-keto dieters, over the course of 2-4 weeks.[3] This is also the result of a well-designed two month metabolic ward study.[66] Free-living studies tend to show slightly greater fat loss in keto dieters, although results aren't consistent.[67]


Muscle Mass

Out of studies that paired exercise with keto diets, and compared them to non-keto diets plus exercise, the findings are mixed.[68][27][69] While the non-keto groups often appear to show better mass retention, much of that may be due to keto groups losing water weight, which is counted as lean mass in body composition measurements.[70][71]


Water Weight

Initial weight loss on a keto diet (meaning the first week) is nearly entirely water and glycogen, rather than fat. You simply cannot lose several pounds of fat in one week absent extreme situations.

As you ratchet down carbs, you use up liver glycogen. Since each gram of glycogen is paired with about 2.4 grams of water,[72] a full male liver is heavier by 289–432 grams (0.6–1.0 lb), and a full female liver is heavier by 241–364 grams (0.5–0.8 lb).[73][74][75] Eventually, you'll tap more and more into your muscle glycogen and empty those stores as well, to the tune of 1.1-1.4 kg (2.4-3.2 lb). Adding this to your liver glycogen, it's easy to lose at least 2-3 kg (5-7 lb) or more of glycogen and water weight.





The ketogenic diet hasn't been tested in randomized trials for acne, eczema, and other common skin conditions. Researchers have proposed that keto may help skin conditions such as acne and psoriasis, and case studies have been reported, but human trials are currently lacking.[76][77]

On the flip side, two case studies have been published on increased carbs helping treat Prurigo pigmentosa (a rare inflammatory dermatitis) in two people who had been on keto diets.[78][79] Ketosis was proposed to be involved in the initiation of the condition.[80]

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)
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)
8.^Sedej SKetone bodies to the rescue for an aging heart?Cardiovasc Res.(2018 Jan 1)
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)
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)
14.^Westman ECIs dietary carbohydrate essential for human nutrition?Am J Clin Nutr.(2002 May)
16.^Sirot V, Leblanc JC, Margaritis IA risk-benefit analysis approach to seafood intake to determine optimal consumptionBr J Nutr.(2012 Jun)
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)
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)
24.^VanItallie TB, Nufert THKetones: metabolism's ugly ducklingNutr Rev.(2003 Oct)
25.^Wheless JWHistory of the ketogenic dietEpilepsia.(2008 Nov)
26.^Kossoff EH, Cervenka MC, Henry BJ, Haney CA, Turner ZA decade of the modified Atkins diet (2003–2013): Results, insights, and future directionsEpilepsy Behav.(2013 Dec)
28.^Caprio M, Infante M, Moriconi E, Armani A, Fabbri A, Mantovani G, Mariani S, Lubrano C, Poggiogalle E, Migliaccio S, Donini LM, Basciani S, Cignarelli A, Conte E, Ceccarini G, Bogazzi F, Cimino L, Condorelli RA, La Vignera S, Calogero AE, Gambineri A, Vignozzi L, Prodam F, Aimaretti G, Linsalata G, Buralli S, Monzani F, Aversa A, Vettor R, Santini F, Vitti P, Gnessi L, Pagotto U, Giorgino F, Colao A, Lenzi A, Cardiovascular Endocrinology Club of the Italian Society of EndocrinologyVery-low-calorie ketogenic diet (VLCKD) in the management of metabolic diseases: systematic review and consensus statement from the Italian Society of Endocrinology (SIE)J Endocrinol Invest.(2019 May 20)
29.^Shilpa J, Mohan VKetogenic diets: Boon or bane?Indian J Med Res.(2018 Sep)
30.^Newman JC, Covarrubias AJ, Zhao M, Yu X, Gut P, Ng CP, Huang Y, Haldar S, Verdin EKetogenic Diet Reduces Midlife Mortality and Improves Memory in Aging MiceCell Metab.(2017 Sep 5)
33.^Harano Y, Kosugi K, Hyosu T, Suzuki M, Hidaka H, Kashiwagi A, Uno S, Shigeta YKetone bodies as markers for type 1 (insulin-dependent) diabetes and their value in the monitoring of diabetic controlDiabetologia.(1984 May)
34.^Avogaro A, Crepaldi C, Miola M, Maran A, Pengo V, Tiengo A, Del Prato SHigh blood ketone body concentration in type 2 non-insulin dependent diabetic patientsJ Endocrinol Invest.(1996 Feb)
35.^Mahendran Y, Vangipurapu J, Cederberg H, Stancáková A, Pihlajamäki J, Soininen P, Kangas AJ, Paananen J, Civelek M, Saleem NK, Pajukanta P, Lusis AJ, Bonnycastle LL, Morken MA, Collins FS, Mohlke KL, Boehnke M, Ala-Korpela M, Kuusisto J, Laakso MAssociation of ketone body levels with hyperglycemia and type 2 diabetes in 9,398 Finnish menDiabetes.(2013 Oct)
36.^Stubbs BJ, Cox PJ, Evans RD, Santer P, Miller JJ, Faull OK, Magor-Elliott S, Hiyama S, Stirling M, Clarke KOn the Metabolism of Exogenous Ketones in HumansFront Physiol.(2017 Oct 30)
37.^Vandenberghe C, St-Pierre V, Pierotti T, Fortier M, Castellano CA, Cunnane SCTricaprylin Alone Increases Plasma Ketone Response More Than Coconut Oil or Other Medium-Chain Triglycerides: An Acute Crossover Study in Healthy AdultsCurr Dev Nutr.(2017 Mar 22)
39.^Westman EC, Feinman RD, Mavropoulos JC, Vernon MC, Volek JS, Wortman JA, Yancy WS, Phinney SDLow-carbohydrate nutrition and metabolismAm J Clin Nutr.(2007 Aug)
40.^Wylie-Rosett J, Aebersold K, Conlon B, Isasi CR, Ostrovsky NWHealth effects of low-carbohydrate diets: where should new research go?Curr Diab Rep.(2013 Apr)
41.^Baccala LA, Nicolelis MA, Yu CH, Oshiro MStructural analysis of neural circuits using the theory of directed graphsComput Biomed Res.(1991 Feb)
42.^Gibson AA, Seimon RV, Lee CM, Ayre J, Franklin J, Markovic TP, Caterson ID, Sainsbury ADo ketogenic diets really suppress appetite? A systematic review and meta-analysisObes Rev.(2015 Jan)
43.^Stubbs BJ, Cox PJ, Evans RD, Cyranka M, Clarke K, de Wet HA Ketone Ester Drink Lowers Human Ghrelin and AppetiteObesity (Silver Spring).(2018 Feb)
44.^Cross JH, McLellan A, Neal EG, Philip S, Williams E, Williams REThe ketogenic diet in childhood epilepsy: where are we now?Arch Dis Child.(2010 Jul)
46.^Musa-Veloso K, Likhodii SS, Cunnane SCBreath acetone is a reliable indicator of ketosis in adults consuming ketogenic mealsAm J Clin Nutr.(2002 Jul)
47.^Calton JBPrevalence of micronutrient deficiency in popular diet plansJ Int Soc Sports Nutr.(2010 Jun 10)
48.^Churuangsuk C, Griffiths D, Lean MEJ, Combet EImpacts of carbohydrate-restricted diets on micronutrient intakes and status: A systematic reviewObes Rev.(2019 Aug)
49.^Ma Y, Pagoto SL, Griffith JA, Merriam PA, Ockene IS, Hafner AR, Olendzki BCA dietary quality comparison of popular weight-loss plansJ Am Diet Assoc.(2007 Oct)
50.^Miller BV, Bertino JS, Reed RG, Burrington CM, Davidson LK, Green A, Gartung AM, Nafziger ANAn evaluation of the atkins' dietMetab Syndr Relat Disord.(2003 Dec)
51.^Kossoff EH, Zupec-Kania BA, Auvin S, Ballaban-Gil KR, Christina Bergqvist AG, Blackford R, Buchhalter JR, Caraballo RH, Cross JH, Dahlin MG, Donner EJ, Guzel O, Jehle RS, Klepper J, Kang HC, Lambrechts DA, Liu YMC, Nathan JK, Nordli DR Jr, Pfeifer HH, Rho JM, Scheffer IE, Sharma S, Stafstrom CE, Thiele EA, Turner Z, Vaccarezza MM, van der Louw EJTM, Veggiotti P, Wheless JW, Wirrell EC, Charlie Foundation, Matthew's Friends, Practice Committee of the Child Neurology SocietyOptimal clinical management of children receiving dietary therapies for epilepsy: Updated recommendations of the International Ketogenic Diet Study GroupEpilepsia Open.(2018 May 21)
53.^McElhiney LF, Cheng A, Meshberger L, Imai LCalculating carbohydrate content of compounded medications for patients on a ketogenic dietInt J Pharm Compd.(2010 Jan-Feb)
57.^Lindefeldt M, Eng A, Darban H, Bjerkner A, Zetterström CK, Allander T, Andersson B, Borenstein E, Dahlin M, Prast-Nielsen SThe ketogenic diet influences taxonomic and functional composition of the gut microbiota in children with severe epilepsyNPJ Biofilms Microbiomes.(2019 Jan 23)
61.^Fang X, An P, Wang H, Wang X, Shen X, Li X, Min J, Liu S, Wang FDietary intake of heme iron and risk of cardiovascular disease: a dose-response meta-analysis of prospective cohort studiesNutr Metab Cardiovasc Dis.(2015 Jan)
63.^Steinberg KK, Cogswell ME, Chang JC, Caudill SP, McQuillan GM, Bowman BA, Grummer-Strawn LM, Sampson EJ, Khoury MJ, Gallagher MLPrevalence of C282Y and H63D mutations in the hemochromatosis (HFE) gene in the United StatesJAMA.(2001 May 2)
64.^Paddon-Jones D, Westman E, Mattes RD, Wolfe RR, Astrup A, Westerterp-Plantenga MProtein, weight management, and satietyAm J Clin Nutr.(2008 May)
65.^Paoli A, Bosco G, Camporesi EM, Mangar DKetosis, ketogenic diet and food intake control: a complex relationshipFront Psychol.(2015 Feb 2)
66.^Hall KD, Chen KY, Guo J, Lam YY, Leibel RL, Mayer LE, Reitman ML, Rosenbaum M, Smith SR, Walsh BT, Ravussin EEnergy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese menAm J Clin Nutr.(2016 Aug)
68.^Vargas S, Romance R, Petro JL, Bonilla DA, Galancho I, Espinar S, Kreider RB, Benítez-Porres JEfficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trialJ Int Soc Sports Nutr.(2018 Jul 9)
69.^LaFountain RA, Miller VJ, Barnhart EC, Hyde PN, Crabtree CD, McSwiney FT, Beeler MK, Buga A, Sapper TN, Short JA, Bowling ML, Kraemer WJ, Simonetti OP, Maresh CM, Volek JSExtended Ketogenic Diet and Physical Training Intervention in Military PersonnelMil Med.(2019 Mar 16)
70.^Roumelioti ME, Glew RH, Khitan ZJ, Rondon-Berrios H, Argyropoulos CP, Malhotra D, Raj DS, Agaba EI, Rohrscheib M, Murata GH, Shapiro JI, Tzamaloukas AHFluid balance concepts in medicine: Principles and practiceWorld J Nephrol.(2018 Jan 6)
71.^Tinsley GM, Willoughby DSFat-Free Mass Changes During Ketogenic Diets and the Potential Role of Resistance TrainingInt J Sport Nutr Exerc Metab.(2016 Feb)
72.^Nilsson LHLiver glycogen content in man in the postabsorptive stateScand J Clin Lab Invest.(1973 Dec)
73.^Molina DK, DiMaio VJNormal Organ Weights in Women: Part II-The Brain, Lungs, Liver, Spleen, and KidneysAm J Forensic Med Pathol.(2015 Sep)
74.^Molina DK, DiMaio VJNormal organ weights in men: part II-the brain, lungs, liver, spleen, and kidneysAm J Forensic Med Pathol.(2012 Dec)
75.^Cahill GF JrFuel metabolism in starvationAnnu Rev Nutr.(2006)
76.^Paoli A, Grimaldi K, Toniolo L, Canato M, Bianco A, Fratter ANutrition and acne: therapeutic potential of ketogenic dietsSkin Pharmacol Physiol.(2012)
77.^Castaldo G, Galdo G, Rotondi Aufiero F, Cereda EVery low-calorie ketogenic diet may allow restoring response to systemic therapy in relapsing plaque psoriasisObes Res Clin Pract.(2016 May-Jun)
78.^Michaels JD, Hoss E, DiCaudo DJ, Price HPrurigo pigmentosa after a strict ketogenic dietPediatr Dermatol.(2015 Mar-Apr)
79.^Maco MW, Lee E, Wu Y, Lee RTreatment of Prurigo Pigmentosa with Diet Modification: A Medical Case StudyHawaii J Med Public Health.(2018 May)
80.^Teraki Y, Teraki E, Kawashima M, Nagashima M, Shiohara TKetosis is involved in the origin of prurigo pigmentosaJ Am Acad Dermatol.(1996 Mar)