A ketogenic diet lowers myocardial fatty acid oxidation but does not affect oxygen consumption: a study in overweight humans
Thien Vinh Luong, Mette Glavind Bülow Pedersen, Caroline Bruun Abild, Stephen C. Cunnane, Etienne Croteau, Katrine Meyer Lauritsen, Mette Louise Gram Kjærulff, Lars Poulsen Tolbod, Niels Møller, Esben Søndergaard, Lars Christian Gormsen- Nutrition and Dietetics
- Endocrinology
- Endocrinology, Diabetes and Metabolism
- Medicine (miscellaneous)
Abstract
Objective
A ketogenic diet (KD) characterized by very low carbohydrate intake and high fat consumption may simultaneously induce weight loss and be cardioprotective. The “thrifty substrate hypothesis” posits that ketone bodies are more energy efficient compared with other cardiac oxidative substrates such as fatty acids. This work aimed to study whether a KD with presumed increased myocardial ketone body utilization reduces cardiac fatty acid uptake and oxidation, resulting in decreased myocardial oxygen consumption (MVO2).
Methods
This randomized controlled crossover trial examined 11 individuals with overweight or obesity on two occasions: (1) after a KD and (2) after a standard diet. Myocardial free fatty acid (FFA) oxidation, uptake, and esterification rate were measured using dynamic [11C]palmitate positron emission tomography (PET)/computed tomography, whereas MVO2 and myocardial external efficiency (MEE) were measured using dynamic [11C]acetate PET.
Results
The KD increased plasma β‐hydroxybutyrate, reduced myocardial FFA oxidation (p < 0.01) and uptake (p = 0.03), and increased FFA esterification (p = 0.03). No changes were observed in MVO2 (p = 0.2) or MEE (p = 0.87).
Conclusions
A KD significantly reduced myocardial FFA uptake and oxidation, presumably by increasing ketone body oxidation. However, this change in cardiac substrate utilization did not improve MVO2, speaking against the thrifty substrate hypothesis.