Research paper
Scheer FAJL, Morris CJ, Shea SA. The internal circadian clock increases hunger and appetite in the evening independent of food intake and other behaviors. Obesity (Silver Spring). 2013;21(3):421-423.
Why we cite it
Provides the cleanest demonstration that evening hunger is driven by the endogenous circadian clock, not by time since last meal or time since waking. The forced desynchrony protocol — the gold standard for isolating circadian effects — separates biology from behavior. This is the primary source for the project's claim that evening eating difficulty is biological, not a character flaw, and that hunger is lowest in the morning despite the longest fast.