One of the frequently repeated criticisms by dietitians of the ketogenic diet is the claim that long term consequences of the diet are unknown. This claim needs to be compared against other diets. The other question is what sort of consequences are being compared against. Also, how long is “long-term”?
Studies on the Long Term Consequences
It is difficult and expensive to do randomized control trials of diets on a long term basis. This gets particularly difficult to do this in a metabolic ward. What other diet has passed this hurdle?
The truth is there have been long term studies of captive populations under controlled conditions.
This 2004 study was a 24-week study which showed favorable results for the ketogenic diet (Exp Clin Cardiol. 2004 Fall; 9(3): 200–205. Long-term effects of a ketogenic diet in obese patients. Hussein M Dashti, MD PhD FICS FACS, Thazhumpal C Mathew, MSc PhD FRCPath, Talib Hussein, MB ChB, Sami K Asfar, MB ChB MD FRCSEd FACS, Abdulla Behbahani, MB ChB FRCS FACSI PhD FICS FACS, Mousa A Khoursheed, MB ChB FRCS FICS, Hilal M Al-Sayer, MD PhD FICS FACS, Yousef Y Bo-Abbas, MD FRCPC, and Naji S Al-Zaid, BSc PhD). From the results:
The present study shows the beneficial effects of a long-term ketogenic diet. It significantly reduced the body weight and body mass index of the patients. Furthermore, it decreased the level of triglycerides, LDL cholesterol and blood glucose, and increased the level of HDL cholesterol. Administering a ketogenic diet for a relatively longer period of time did not produce any significant side effects in the patients. Therefore, the present study confirms that it is safe to use a ketogenic diet for a longer period of time than previously demonstrated.
There could be some currently unknown test that the ketogenic diet might be demonstrated to be negative but no study has shown a negative effect.
Another [small] patient population (n=3) has been studied for five years. This population has aglucose transporter 1 deficiency syndrome (GLUT-1 DS) that is only treatable with a ketogenic diet. That study which focused on bone density and body composition is described in this study (Nutrition, 2014, 30(6), 726-728. Long-term effects of a ketogenic diet on body composition and bone mineralization in GLUT-1 deficiency syndrome: a case series. Bertoli, S., Trentani, C., Ferraris, C., De Giorgis, V., Veggiotti, P., & Tagliabue, A.). From the results:
Our data suggest that maintaining a Ketogenic Diet for more than 5 years does not pose any major negative effects on body composition, bone mineral content, and bone mineral density in adults with GLUT-1 DS…
Let’s take this up a notch. Where’s the proof that any other diet has similar safety? The low fat switch was made with zero evidence and all of the evidence in the meanwhile has shown low-fat was a bad choice.
A recent, longer study of the same sort of patients (GLUT-1 deficient patients) was done (Clin Nutr. 2017 Nov 11. 10 patients, 10 years – Long term follow-up of cardiovascular risk factors in Glut1 deficiency treated with ketogenic diet therapies: A prospective, multicenter case series. Heussinger N, Della Marina A, Beyerlein A, Leiendecker B, Hermann-Alves S, Dalla Pozza R, Klepper J.). From the results:
Baseline and 10 year follow-up investigations were available for 10 individuals with Glut1D on KDT. After two years on KDT BMI increased significantly, while total cholesterol, HDL-cholesterol, and LDL-cholesterol decreased. Within 3-5 years on KDT these differences disappeared, and after 10 years blood lipid parameters reflected the situation at initiation of KDT. Prior to KDT one child had dyslipidaemia, but no child after 10 years on KDT. No significant differences were observed with respect to BMI SDS (p = 0.26), CIMT (p = 0.63) or systolic and diastolic blood pressure (SDS p = 0.11 and p = 0.37, respectively) in Glut1D children treated with KDT for at least 10 years compared to healthy controls.
Children with seizures have been treated with the ketogenic diet since the 1920’s.
This is a very interesting study with a shorter term but surprisingly good results for the ketogenic diet (Nutr Metab (Lond). 2018; 15: 18. Resting metabolic rate of obese patients under very low calorie ketogenic diet.
Diego Gomez-Arbelaez, Ana B. Crujeiras, Ana I. Castro, Miguel A. Martinez-Olmos, Ana Canton, Lucia Ordoñez-Mayan, Ignacio Sajoux, Cristobal Galban, Diego Bellido, and Felipe F. Casanueva). The study results were:
The rapid and sustained weight and Fat Mass loss induced by VLCK-diet in obese subjects did not induce the expected reduction in Resting Metabolic Rate, probably due to the preservation of lean mass.
Over 250 medical centers worldwide offer ketogenic diets to children with epilepsy. This study looked at five years (Epilepsy Behav. 2016 May;58:61-8. Establishing an Adult Epilepsy Diet Center: Experience, efficacy and challenges. Cervenka MC, Henry BJ, Felton EA, Patton K, Kossoff EH.)
This study, the largest series of adults with epilepsy treated with ketogenic diet therapies to date, provides evidence that ketogenic diets may be feasible, effective, and safe long-term in adults…