Caffeine boosts ketone production.
(Vandenberghe, Camille, et al. “Caffeine intake increases plasma ketones: an acute metabolic study in humans.” Canadian Journal of Physiology and Pharmacology 95.4 (2016): 455-458.)
Caffeine given at two different doses, 2.5 mg per kg of body weight, or 5.0 mg/kg, stimulated ketone production as much as an overnight fast.
“This short-term study showed that caffeine intake can stimulate ketogenesis by increasing β-HB concentrations by 88-116% with a maximum within four hours post-dose .”
The lower dose, 2.5 mg/kg is equivalent to about 1.5 cups of coffee for a person who weighs 70 kg, and the higher dose to about 3 cups.
So, the dose is well within what many people drink already.