Research paper
Ravussin E, Beyl RA, Poggiogalle E, Hsia DS, Peterson CM. Early time-restricted feeding reduces appetite and increases fat oxidation but does not affect energy expenditure in humans. Obesity (Silver Spring). 2019;27(8):1244-1254. doi:10.1002/oby.22518
Why we cite it
A rigorous respiratory-chamber crossover trial that definitively showed early time-restricted feeding works through appetite suppression, not metabolic boosting. The headline finding for the project: despite a longer daily fast (18 hours vs. 12 hours), eTRF *decreased* ghrelin by 32 pg/mL and made hunger more "even-keeled" — directly demonstrating that the hunger system adapts to a consistent eating window. The null result on 24-hour energy expenditure (Δ=10 kcal/day, p=0.55) is equally important: it refutes the popular claim that fasting "boosts metabolism." Together with Natalucci et al. 2005 (csh02, showing ghrelin maintains meal-related patterns during fasting) and Cummings et al. 2001 (csh01, showing preprandial ghrelin surges), this paper completes the hunger-adaptation evidence base: hunger is scheduled, adapts to new patterns, and stabilizes with consistency.