Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 19 (1), 62

The Effect of a Ketogenic Diet Versus a High-Carbohydrate, Low-Fat Diet on Sleep, Cognition, Thyroid Function, and Cardiovascular Health Independent of Weight Loss: Study Protocol for a Randomized Controlled Trial


The Effect of a Ketogenic Diet Versus a High-Carbohydrate, Low-Fat Diet on Sleep, Cognition, Thyroid Function, and Cardiovascular Health Independent of Weight Loss: Study Protocol for a Randomized Controlled Trial

Stella Iacovides et al. Trials.


Background: Many physiological health benefits observed after following a ketogenic diet (KD) can be attributed to the associated weight loss. The KD has become more prominent as a popular health choice, not only in obese/overweight individuals, but also in healthy adults. The study aims to determine the effects of a KD, independent of weight loss, on various aspects of physiological health including: sleep, thyroid function, cognition, and cardio-metabolic health. The study will also aim to determine whether a change in basal metabolic rate may be associated with any changes observed.

Methods: Twenty healthy men and women between 18 and 50 years of age will take part in this study. In a randomized controlled, cross-over design, participants will follow two isocaloric diets: a high-carbohydrate, low-fat diet (55% CHO, 20% fat, 25% protein) and a KD (15% CHO, 60% fat, 25% protein). Each dietary intervention will last for a minimum of 3 weeks, with a 1-week washout period in between. Before and after each diet, participants will be assessed for sleep quality, cognitive function, thyroid function, and basal metabolic rate. A blood sample will also be taken for the measurement of cardio-metabolic and immune markers.

Discussion: The present study will help in understanding the potential effects of a KD on aspects of physiological health in healthy adults, without the confounding factor of weight loss. The study aims to fill a significant void in the academic literature with regards to the benefits and/or risks of a KD in a healthy population, but will also explore whether diet-related metabolic changes may be responsible for the changes observed in physiological health.

Trial registration: Pan African Clinical Trial Registry ( ), trial number: PACTR201707002406306 . Registered on 20 July 2017.

Keywords: Cognition; Healthy participants; High-fat; Ketogenic diet; Low-carbohydrate; Metabolism; Sleep; Thyroid function.

Conflict of interest statement

Ethics approval and consent to participate

The study has been approved by the University of the Witwatersrand Human Research Ethics Committee (clearance number: M150849). All participants will be fully informed of the procedures of the study and will sign an informed consent form prior to participation in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


Fig. 1
Fig. 1
Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) schedule of enrollment, interventions, and assessments for the duration of the study. HCLF = High carbohydrate, low fat diet; KD= ketogenic diet, BMR = basal metabolic rate
Fig. 2
Fig. 2
Timeline and details of study procedures

Similar articles

See all similar articles

Cited by 5 articles


    1. Dixon JB, Dixon ME, Anderson ML, Schachter L, O’Brien PE. Daytime sleepiness in the obese: not as simple as obstructive sleep apnea. Obesity. 2007;15(10):2504–11. doi: 10.1038/oby.2007.297. - DOI - PubMed
    1. Dixon JB, Schachter LM, O’Brien PE. Sleep disturbance and obesity: changes following surgically induced weight loss. Arch Intern Med. 2001;161(1):102–6. doi: 10.1001/archinte.161.1.102. - DOI - PubMed
    1. Alosco ML, Gunstad J. The negative effects of obesity and poor glycemic control on cognitive function: a proposed model for possible mechanisms. Curr Diab Rep. 2014;14(6):495. doi: 10.1007/s11892-014-0495-z. - DOI - PMC - PubMed
    1. Whitmer RA, Gustafson DR, Barrett-Connor E, Haan MN, Gunderson EP, Yaffe K. Central obesity and increased risk of dementia more than three decades later. Neurology. 2008;71(14):1057–64. doi: 10.1212/01.wnl.0000306313.89165.ef. - DOI - PubMed
    1. Kopelman P. Health risks associated with overweight and obesity. Obes Rev. 2007;8(Suppl 1):13–7. doi: 10.1111/j.1467-789X.2007.00311.x. - DOI - PubMed

Publication types

MeSH terms