COGNITIVE EFFECTS OF KETOGENIC WEIGHT-REDUCING DIETS

OBJECTIVE: To determine whether ketogenic weight reducing diets have a dverse effects on cognitive performance, SUBJECTS: 21 overweight women (mean BMI = 41 kg/m(2)). DESIGN: Randomized double-blinded study, MET HOD: Subjects were randomized to ketogenic or nonketogenic liquid form ula very low energy diets, that were comparable in energy and in prote in content, Subjects remained on the diet for 28 days and were reevalu ated periodically with brief measures of cognitive performance assessi ng attention and mental flexibility, RESULTS: Weight losses were compa rable 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 ord er mental processing and flexibility, was adversely affected by the ke togenic diet, The worsening in performance was observed primarily betw een baseline and week one of the ketogenic diet, CONCLUSIONS: Further research is needed to confirm this finding and to determine whether ke togenic diets negatively affect other complex mental tasks, such as pr oblem solving.