Key result
A ketogenic diet reduced myocardial free fatty acid uptake and oxidation but did not affect myocardial oxygen consumption (P=0.2) compared with a standard diet.
Why the study?
It was unknown whether a ketogenic diet reduces cardiac fatty acid uptake and oxidation to decrease myocardial oxygen consumption, testing the thrifty substrate hypothesis.
Does a ketogenic diet reduce myocardial oxygen consumption in individuals with overweight or obesity?
RCT (n=11)
Randomized crossover
Does a ketogenic diet reduce myocardial oxygen consumption in individuals with overweight or obesity?
p-value: p=0.2
A ketogenic diet reduces myocardial fatty acid uptake and oxidation but does not improve myocardial oxygen consumption, challenging the thrifty substrate hypothesis.
KD may shift cardiac substrates in obesity without efficiency gains; leaves open clinical outcome effects.
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 (MVO 2 ). 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 [ 11 C]palmitate positron emission tomography (PET)/computed tomography, whereas MVO 2 and myocardial external efficiency (MEE) were measured using dynamic [ 11 C]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 MVO 2 ( 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 MVO 2 , speaking against the thrifty substrate hypothesis.
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Luong et al. (2024) conducted an RCT in Overweight or obesity (n=11). Ketogenic diet vs. Standard diet was evaluated on Myocardial oxygen consumption (MVO2) (p=0.2). A ketogenic diet reduced myocardial free fatty acid uptake and oxidation but did not affect myocardial oxygen consumption (P=0.2) compared with a standard diet.
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