Cognitive effects of ketogenic weight-reducing diets.
OBJECTIVE
To determine whether ketogenic weight reducing diets have adverse effects on cognitive performance.


METHODS
21 overweight women (mean BMI = 41 kg/m2).


METHODS
Randomized double-blinded study.


METHODS
Subjects were randomized to ketogenic or nonketogenic liquid formula very low energy diets, that were comparable in energy and in protein content. Subjects remained on the diet for 28 days and were reevaluated periodically with brief measures of cognitive performance assessing attention and mental flexibility.


RESULTS
Weight losses were comparable on the two diets (Mean = 8.1 kg). Performance on attention tasks did not differ as a function of the diet. However, performance on the trail making task, a neuropsychological test that requires higher order mental processing and flexibility, was adversely affected by the ketogenic diet. The worsening in performance was observed primarily between baseline and week one of the ketogenic diet.


CONCLUSIONS
Further research is needed to confirm this finding and to determine whether ketogenic diets negatively affect other complex mental tasks, such as problem solving.
Wing
R R
RR
Department of Psychiatry, University of Pittsburgh School of Medicine, PA, USA.
Vazquez
J A
JA
Ryan
C M
CM
D000328:Adult; D003071:Cognition / Q000502:physiology*; D004038:Diet, Reducing / Q000009:adverse effects* / Q000592:standards; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D002149:Energy Intake; D005260:Female; D006801:Humans; D007659:Ketones / Q000097:blood / Q000378:metabolism* / Q000652:urine; D008875:Middle Aged; D009767:Obesity, Morbid / Q000178:diet therapy* / Q000503:physiopathology / Q000523:psychology
D004040:Dietary Carbohydrates; D007659:Ketones