This was a randomized control study. Unfortunately, full article behind a pay/subscription wall.
Abstract
Brain glucose uptake declines during aging and is significantly impaired in Alzheimer’s disease. Ketones are the main alternative brain fuel to glucose so they represent a potential approach to compensate for the brain glucose reduction. Caffeine is of interest as a potential ketogenic agent owing to its actions on lipolysis and lipid oxidation but whether it is ketogenic in humans is unknown. This study aimed to evaluate the acute ketogenic effect of 2 doses of caffeine (2.5; 5.0 mg/kg) in 10 healthy adults. Caffeine given at breakfast significantly stimulated ketone production in a dose-dependent manner (+88%; +116%) and also raised plasma free fatty acids. Whether caffeine has long-term ketogenic effects or could enhance the ketogenic effect of medium chain triglycerides remains to be determined.
Fortunately, this appears to be the full study:
Discussion
This short-term study showed that caffeine intake can stimulate ketogenesis by increasing β-HB concentrations by 88%–116% with a maximum within 4 h post-dose. A dose–response was observed
for plasma β-HB (Fig. 2D) but not for AcAc (Fig. 2C), which could be explained by the larger intergroup variation in AcAc. The increase in plasma ketones obtained with these doses of caffeine could at least transiently contribute to 5%–6% of brain energy needs (Cunnane et al. 2016)…