Effects of the ketogenic diet on nutritional status, resting energy expenditure, and substrate oxidation in patients with medically refractory epilepsy: a 6-month prospective observational study

Background & aims: This 6-month prospective, single-arm observational study was designed to assess the effects of the KD on the nutritional status, resting energy expenditure (REE), and substrate oxidation in patients with drug-resistant epilepsy. Methods: Eighteen patients with medically refractory epilepsy underwent assessment of body composition, REE, and substrate oxidation rates before and after 6 months of MD. Results: Compared with baseline, there were no statistically significant differences at 6 months in terms of height, weight, BMI z-scores, and REE. However, the respiratory quotient decreased significantly (from 0.80 +/- 0.06 to 0.72 +/- 0.05,p < 0.001) whereas fat oxidation was significantly increased (from 50.9 +/- 25.2 mg/min to 97.5 +/- 25.7 mg/min, p < 0.001). Interestingly, we found that the increase in fat oxidation was the main independent predictor of the reduction in seizure frequency (beta = -0.97, t = -6.3, p < 0.05). Conclusions: Administering a MD for 6 months in patients with medically refractory epilepsy increases fat oxidation and decreases the respiratory quotient, without appreciable changes in REE.